Survey of Stunning and Handling in Federally Inspected Beef, Veal, Pork, and Sheep Slaughter Plants

Agricultural Research Service/United States Department of Agriculture - 3602-20-00
Project Number -3602-32000-002-08G

Temple Grandin, Ph.D.
Grandin Livestock Handling Systems, Inc.
2918 Silver Plume Dr., Unit C3
Fort Collins, Colorado 80526
January 7, 1997

2002 Update

This survey was conducted in 1996 before the restaurant companies such as McDonald's, Wendy's, and Burger King started auditing plants for animal welfare. In 1999, stunning and handling practices greatly improved after the audits started. This improvement has been maintained and this 1996 survey serves as baseline data prior to industry improvements. In 2001, the USDA also improved humane slaughter enforcement by hiring additional veterinarians. More recent audit data is available on this website in the survey section.


This survey was requested by the USDA to make recommendations for alternative systems/approaches that insure humane handling. The survey consisted of visiting plants and using both objective scoring methods, and subjective ratings based on the author's twenty years of experience to assess stunning, handling, and other parts of the plant's operations which would affect animal welfare.


A total of 24 federally inspected plants were visited in 1996 in ten different states. Sixteen plants were visited in four randomly chosen cities, and to insure confidentiality, an additional eight plants in undisclosed locations were visited. Both very large and very small plants were surveyed. It is the author's opinion that the surveyed pork plants were very representative of the pork industry, and that the sample of beef plants would have been fully representative if it had included one or two additional, very large plants. All visits were announced. Each plant was objectively scored in the following areas:

  1. Percentage of pigs and sheep where the electric stunner was placed in the wrong position.

  2. Percentage of cattle which had to be shot more than once with the captive bolt stunner.

  3. Percentage of sensible and partially sensible animals on the bleed rail.

  4. Percentage of animals falling down or slipping.

  5. Percentage of cattle vocalizing in the stunning chute area.

  6. Percentage of pigs or cattle vocalizing in the stunning box or restrainer.

  7. Percentage of animals prodded with an electric prod.

Subjective ratings based on the author's experience in several hundred slaughter plants were also used. Ratings of excellent, acceptable, not acceptable, or serious problem were given in the following areas:
Handling of non-ambulatory animals was also rated and tabulated. See full report for more explanation of the ratings.

Summary of Results

Captive bolt stunners used on cattle had more maintenance and ergonomics problems than electric stunners used on pigs. In both species stunning procedures need to be improved. Seven out of eleven (64%) pork plants and sheep plants were rated either excellent or acceptable for correct electric stunner placement with a 99% or more correct placement score. Only one plant was using less than the recommended amperage setting of 1.25 amps for market weight pigs. Two plants (18%) had a serious problem with correct stunner placement due to use of the wrong type of electrode wands. In these two plants animal welfare would have been severely compromised because 10% to 35% of the animals were stunned on the neck. In both fed beef and non-fed beef there needs to be a big improvement in efficacy of captive bolt stunning. Only 4 out of 11 surveyed plants (36%) were rated either acceptable or excellent with 95% to 100% of the cattle rendered obviously insensible with one shot. Seven plants (64%) were rated either not acceptable or a serious problem with one shot scores ranging from 91% to 80%. The cause of the missed shots in these plants were:

To improve captive bolt first shot efficacy percentages, maintenance and pneumatic gun ergonomics must be improved. One of the surveyed plants improved their one shot score from 85% to over 99% with a combination of ergonomic changes, stunner bolt lengthening, and improved maintenance. Attempting to improve stunning accuracy with a head restraint device may increase stress. The author recommends that the main emphasis be put on better gun maintenance and improving pneumatic gun ergonomics so that less effort is required to position the stunner. In both beef and pork plants, the employees made sure that animals were insensible prior to shackling and hoisting. Over 1000 cattle and calves and over 1000 pigs and sheep were observed. There was only one possibly sensible pig due to operator error and one sensible beef animal. The beef animal was immediately shot, and it was probably an artifact of the survey. The stunner operator was nervous and trying very hard to get a good first shot score. Overall the plants were rated excellent for insensibility because butchering procedures were never started on possibly sensible animals. Slick floors which caused animals to slip or fall in the stunning chute area were a serious problem that compromised animal welfare in four out of eleven (36%) of the plants which processed cattle or calves. In these four plants 15 to 30% of the animals slipped to the point that it interfered with quiet handling. In two plants 8 to 12% of the animals fell down. The biggest problem area was slipping in the stunning box which caused cattle to become agitated. All eleven pork and sheep plants were rated as excellent or acceptable for flooring in the stunning chute area. Floors in the stunning boxes can be made non-slip by installing a grating for under $1000.


Overall handling of both cattle and pigs was much better in the yards than in the stunning chute area. All plants surveyed had either excellent or acceptable handling in the yards. In the stunning chute area seventy-seven percent (17 plants) were rated either excellent or acceptable and twenty-three percent (5 plants) were rated either not acceptable or a serious problem. The two plants that received a serious problem rating were both beef plants. In one of these plants, electric prods were used to paralyze cattle prior to stunning, and in the other, 32% of the cattle vocalized due to excessive electric prod use. Employees supervised by the livestock procurement department handled animals more carefully than employees supervised by the slaughter department. Slaughter foremen in two plants prodded pigs and cattle excessively.

Out of 15 plants where the use of electric prods was scored, seventy-three percent (11 plants) had employees who only prodded animals that stopped moving or they used an electric prods that was so weak that they had little effect on the animals. In three beef plants and one pork plant, ninety percent of the animals entered the stunning box or restrainer without the use of an electric prod. These four plants received an excellent rating for electric prod use. In one beef and one pork plant animals refused to enter and 64% and 80% respectively had to be prodded. This was due to easily correctable lighting problems and seeing moving people. Easy to remove distractions such as air hissing, shadows, seeing people moving up ahead, or shiny reflections caused balking and impeded livestock movement in 9 out of 19 pork and beef plants. It was possible to significantly reduce electric prod percentages in the two beef and two pork plants which had the highest percentages by briefly showing the employees how to move smaller groups of animals. The empolyees were also instructed not to prod an animal with an electric prod unless it refused to move after one or two taps on the rear. The average percentage of animals electric prodded in these four plants was reduced from 52% to 14% in the crowd pen, and 63% to 16% in the stunning chute . (Chi square <.001). The slaughter line was kept full when electric prodding was reduced. Seventy-seven percent of the plants were rated either excellent or acceptable for electric prod equipment and thirty-three percent were rated a serious problem due to having prods of sufficient strength to cause many animals to vocalize. Vocalization scoring was used in beef plants to further quantify stress during handling in the stunning area. It was not used in pork plants for evaluating handling and electric prod use due to the difficulty of counting individual pig squeals. Eight beef and calf plants were vocalization scored. Fifty percent (4 plants) were rated excellent or acceptable with less than 3% of the bovines vocalizing. Two plants (25%) were rated a serious problem with 12 to 35% of the cattle vocalizing. The main cause of vocalization was excessive electric prodding, slipping in the stunning box, or excessive pressure from a restraint device. Vocalizations were significantly reduced in the two beef plants with excessive prodding from 22% to 7% after electric prodding was reduced (Chi square <.001). The remaining vocalizations were induced by excessive pressure from a restraint device. Even though squealing during pig handling could not be numerically quantified it was obvious to the author that the plant with the best handling had the least squealing. Possibly a sound level meter could be used to quantify vocalizations in pigs.

Stunning boxes, conveyor restrainers and restraint devices were scored for vocalization and animal agitation in 15 pork, beef, and veal plants. Eleven out of fifteen plants (73%) were rated either excellent or acceptable.

In half the pork plants, none of the pigs vocalized in the conveyor restrainer.
One pork restrainer was rated not acceptable because 14% of the pigs squealed due to a missing part.
Five beef and veal plants were rated as excellent with vocalization percentages of 0% to 0.6% in the stunning box or restrainer.
Three beef plants were rated either not acceptable or a serious problem for vocalizations due to :
  1. excessive pressure exerted by a restraint device which caused 7.5% of cattle to vocalize
  2. use of electricity to paralyze cattle during stunning
  3. a stun box with a slick floor which caused 40% of the cattle to become agitated.
A comparison between a pork plant with the highest prod score and three pork plants with very low prod scores indicated that the high electric prod plant had three times as many deads and non-ambulatory stressed pigs.


Slaughter Equipment used to restrain cattle for kosher slaughter was evaluated in three plants.

All of these problems which caused the cattle to vocalize can be easily corrected. Cattle do not appear to react or show obvious indicators of distress when the kosher cut is done correctly.
Only one miscut was observed out of 362 cattle.
This is a considerably better percentage compared to the stunning efficacy rate in the other beef plants. Three different shochets were observed. All three surveyed plants used a restraint device that held the cattle in an upright position. Good animal welfare can be maintained during ritual slaughter if the animal is quietly held in a well designed restraint device that holds it in an upright position. The first kosher plant surveyed would be rated excellent from an animal welfare standpoint.
Any plant which shackles and hoists fully conscious cattle would be rated a serious problem.

Conditions in Plant Yards and Truck Unloading Area

Ninety-two percent of the plants stocked the livestock holding pens at a stocking level which was rated either excellent or acceptable. All the pigs had sufficient space to lie down, with the exception of one plant which was rated as not acceptable. There were no serious problems. Only one plant had no water for the livestock. Seventy-eight percent of the plants had pens, gates, and unloading ramp facilities which were in an adequate state of repair. Two plants (11%) of the 18 plants surveyed for yard conditions had yards in a bad state of disrepair. In the yards and truck unloading area none of the beef plants were rated as having a serious problem with slipping, and in pork, only one plant (11%) was rated a serious problem for having an unloading ramp that pigs slid down. Eighty percent of the beef plants, 66% of the pork plants, and the two sheep plants were rated excellent or acceptable for slipping and falling in the yards.

Truck Unloading and Vehicles

Overall the quality of the vehicles which were used to transport livestock to the plants was excellent. There were very few really poor vehicles. Most problems observed were caused by people, such as overloading or excessive electric prodding. Problems due to very hot or cold weather were not observed because the weather was mild during the weeks that the survey was conducted. Out of 57 beef and pork trucks the drivers did either an excellent or acceptable job on 96% of the beef trucks and 72% of the pork trucks. Overall, only 12% of the truck drivers were rated a serious problem for either excessive prodding or overloading.

Condition of Animals

The condition of over 99% of the cows and bulls was either excellent or acceptable because the six surveyed cow and bull plants did not buy non-fed cattle which were in poor condition. There is a concern about emaciated cows and cattle with severe ocular neoplasia going into an underground market. A truck driver interviewed during the survey said he transported cows with severe ocular neoplasia to Mexico. There are serious concerns with the condition of cull sows, especially sows with lean genetics arriving from large farms. Approximately 16% of the sows unloaded from five randomly chosen trucks at one plant were severely lame. Another problem area is lean genetic type pigs which are very excitable and difficult to drive. This can cause serious welfare problems in high speed plants.


The author recommends that a HACCP type program using objective measurable criteria be used to insure welfare. The author is making these recommendations because the USDA requested "recommendations for alternative systems/approaches that assure humane handling". The survey results clearly showed that there were many more welfare problems in the stunning chute area compared to the yards and truck unloading area. The problems were due to easily correctable faults in equipment and lack of proper supervision of employees. For this reason most recommendations for HACCP type procedures are in the stunning chute area. This area consists of the crowd pen, lead up chute, stunning box or restrainer and bleed area. The economic cost to the meat industry will be minimal and all of the plants surveyed should be able to achieve the author's minimum acceptable criteria without purchasing a major piece of equipment such as a restrainer or new chute system. Simple equipment changes and improvements such as a non-slip floor grating in a cattle stunning box to prevent slipping, eliminating shadows, air hissing, and other distractions that cause balking or adding ergonomic improvements to a pneumatic stunner will enable most plants to achieve a high level of animal welfare. A few plants may need to purchase new stunning equipment. In most plants, equipment improvements and repairs will cost less than $1000. There will be economic benefits in reduced bruises and stressed meat when plants improve animal handling procedures. Quiet handling and minimum use of electric prods will help preserve meat quality and reduce bruises.


Captive bolt scoring should be conducted at both the beginning and at the end of each shift to insure that the gun delivers enough impact to render the animals insensible with one shot. Electric stunners should be checked at least twice daily to insure that the amperage setting is a minimum of 1.25 amps for market weight pigs and 1 amp for sheep (Hoenderken 1982, Gregory 1988, Council of Europe 1991, Gregory and Wotton 1984). Refer to the full report for more information. Each plant should develop stunner maintenance programs that can be verified and documented. Careful maintenance is especially important for captive bolt guns. The results of the survey clearly showed that plants can easily achieve the following objective stunning efficacy criteria. Stunning should be monitored at both the beginning and near the end of each shift. The use of computerized systems to monitor the efficacy of electric stunning should be encouraged.

Captive Bolt - Stunning Efficacy Criteria
If one shot efficacy falls below 95% -
immediate action must be taken to improve the percentage.

Electric Stunning - Electrode Placement Efficacy Criteria
If stunner placement falls below 98% correct, immediate action
must be taken to improve placement percentages.

Stunning to Bleed Interval Penetrating Captive Bolt Bleed Interval - Does not have to be measured for welfare reasons unless non-penetrating captive bolt is used. Additional study would be needed to determine the recommended interval for non-penetrating captive bolt. All plants surveyed used penetrating captive bolt. Electric Stunning Bleed Interval- Cardiac Arrest - Sixty second maximum. All large plants are already less than this interval. Head Only Reversible Electric - Fifteen seconds is strongly recommended (Blackmore and Newhook 1981), 30 seconds maximum (Hoenderken 1983). Scientific research clearly shows that pigs will start returning to sensibility after 30 seconds when stunned by the head only method. Bleed Rail Insensibility - Criteria for stunned animals possibly showing partial sensibility.
Percentages above this would be a serious problem.

This should be checked at both the beginning and near the end of the shift. The following signs are indicators of possible return to sensibility. Animals displaying any one of these signs must be immediately shot with a captive bolt stunner:

  1. rhythmic breathing
  2. vocalizations
  3. eye reflexes in response to touch
  4. eye blinking
  5. arched back righting reflex.
Animals should hang straight on the rail and have a floppy head. Limb movements should be ignored. If the tongue is hanging straight out the animal is definitely insensible. There should be a zero tolerance for hanging a fully sensible, unstunned animal in an inverted position on the bleed rail.

Scoring of Slipping and Falling in the stunning Chute Area (All Species)
Includes Restrainer Entrance, Stunning Box, Lead Up Chute and Crowd Pen.

Should be monitored once a week.

Vocalization Scoring

The survey clearly showed that vocalization in cattle can be easily quantified. During handling, driving, and restraining, cattle usually vocalize in direct response to an aversive event such as excessive electric prodding, slipping and losing their footing, excessive pressure from restraint devices or separation from the other animals. Vocalization scoring by counting individual vocalizations should only be used in the stunning chute area because cattle standing quietly in the yards will often vocalize to each other. Vocalization scoring must not be used for sheep and it can be used in a subjective manner during pig handling. The use of sound level monitoring equipment for assessing stress in pigs should be studied.

Criteria for Vocalization of Cattle in the Crowd Pen, Leadup Chute, Stunning Box or Restraining Device

When vocalization is being evaluated cattle from more than one feedlot or ranch should be observed. Recommend weekly monitoring.

Electric Prod Scoring

This can be used for both cattle and pigs. Data should be collected separately in both the crowd pen and at the stunning box or restrainer entrance. Recommend weekly monitoring, and animals from more than one origin should be observed. The percentages in the prod scoring chart can be easily achieved by improving handling techniques and removing distractions which cause balking (see full report).

Electric Prod Scoring Criteria for Cattle
Percentages of Animals Prodded

Crowd Pen to Chute Entrance of Stunning
Box or Restrainer
Total Percentages
of Cattle Prodded
Excellent none 5% or less 5% or les
Acceptable 5% or less 20% or less 25% or less
Serious Problem -- -- 50% or more

Electric Prod Scoring Criteria for Pigs

Crowd Pen to Chute Entrance of Restrainer Total Percentages
of Pigs Prodded
Excellent none 10% or less 10% or less
Acceptable -- -- 25% or less
Serious Problem
which must be corrected
-- 80% or more

Handling Recommendations to Improve Welfare and Reduce Electric Prod Usage and Vocalizations in Cattle and Pigs

  1. Remove distractions which cause balking such as shadows, ventilation air blowing into the faces of approaching animals, air hissing or sparkling reflections. Animals will balk if they see people moving ahead of them or moving objects. Increasing lighting over the restrainer or moving lights will often improve animal movement. See the full report for more information.
  2. Move small groups of cattle and pigs and never fill the crowd pen or staging area more than one half to three quarters full. Sheep can be moved in larger groups.
  3. Replace electric prods as much as possible with other driving aids such as plastic paddles, panels for moving pigs or whips with plastic streamers attached to them.
  4. Install pressure regulators on restraint devices to reduce pressure applied to the animal and train the operator to operate the restrainer correctly. See full report for further information.
  5. Install a grating or cleats to provide non-slip footing in cattle stunning boxes and in the entrance to animal restrainer systems. Animals often become highly agitated when they slip and lose their footing. See full report for further information.

It is the author's opinion that the following practices constitute cruelty to animals and they should not be allowed.

  1. Use of electricity to immobilize sensible animals to hold them still prior to stunning.
  2. Electric prods which have sufficient power to knock an animal down or cause animals to vocalize when prodded only once.
  3. Shackling and hoisting fully sensible conscious animals prior to ritual slaughter. Good animal welfare can be maintained during ritual slaughter with the use of a restraint device which holds the animals in a comfortable, upright position.

Recommendations to Improve the Welfare of Non-ambulatory Animals and Non-Ambulatory Animal Recommendations

  1. The USDA should perform ante-mortem inspection of non-ambulatory animals which arrive on a vehicle before the animal is unloaded. This would make it possible to stun the animal on the vehicle before it is dragged out. In Canada when a downed animal arrives on a truck it is stunned before it is dragged off (Grandin 1993). It is nearly impossible to humanely remove a downed cow from the center compartment of a double deck cattle trailer. See full report for recommendations on safety for USDA personnel during ante-mortem inspection on a vehicle.
  2. Bulls observed mounting cows should be immediately removed form the pen. Bulls mounting cows is one cause of downed cows.
  3. The introduction of new lean pork genetics is related to an increased incidence of both deads and stressor pigs. The pork industry needs to take steps to eliminate the PSS stress gene and produce calmer pigs which are easier to handle. Highly excitable pigs cause severe handling problems in high speed slaughter plants. The prevalence of this type of pig has been increasing. The possibly worsening condition of cull sows with lean genetics needs further study. See full report for further information.
  4. There is a need for more small plants to process non-ambulatory dairy cows. They should be located in areas close to large dairies. Downed cows can be brought immediately to these plants before their condition deteriorates. These plants will help prevent the formation of an underground market in non-ambulatory dairy cows. An underground market would create serious welfare problems and could have the potential to create food safety problems. Tame non-ambulatory dairy cows can be moved and transported at a good standard of welfare in small van-type trucks equipped with a powered tailgate lift. A powered tailgate lift is essential to eliminate dragging on the farm. Non-ambulatory dairy cows should not be transported for more than 2 hours. The truck driver should take the temperature of a cow at the dairy. If it is either too high or too low she should be immediately euthanized and taken to a rendering plant.

Due to the longer distances and lack of a sufficient concentration of range cows in one area it is strongly recommended to euthanize non-ambulatory beef cows and bulls at the ranch of origin. Any bovine with severe ocular neoplasia or severe emaciation with a body condition score of 1 should be euthanized on the farm. A verbal report from one truck driver indicated that he transported cattle that were in an emaciated condition or had severe ocular neoplasia to Mexico. For both animal welfare and food safety reasons, the author recommends that the export of severely debilitated livestock to Mexico should be stopped.



Sample Selection A total of twenty-four Federally inspected plants were surveyed in ten different states.

Profile of Surveyed Plants

Number of Plants
Animal Type Range of Processing Speeds
Number of Animals Per Hour
5 Fed Cattle 90 to > 250
6 Cows and Bulls 5 to > 150
3 Kosher Cattle 90 to 200
1 Formula Veal 75
2 Sheep and Lambs 75 to > 200
8 Market Pigs 400 to 1000
2 Sows and Boars 170 to 300

A total of 24 plants were surveyed in ten different states. Within this sample there are 16 federally inspected plants which were located in the vicinity of four randomly chosen cities. An additional eight federally inspected plants were added to the sample to provide a larger sample and to insure confidentiality.

1Number of plants adds to more than twenty-four because Kosher plants also do non-kosher slaughter. Some plants were not scored and rated for every variable surveyed.

Both large and small plants were surveyed. To keep travel costs reasonable, a plant city method was used to provide a stratified random sample. Sixteen of the plants were selected by this method. A strict objective criteria was used for selecting both the cities and plants so that the author's knowledge of the industry would not influence plant selection. A total of ten primary cities and ten secondary cities which had a sufficient number of plants in their vicinity were picked with the aid of meat company lists, from meat trade magazines. To insure that a variety of different types of plants were included in the sample, a primary city had to satisfy the following criteria. It had to have an airport with car rental and three to four plants within a reasonable driving distance. It also had to have at least one plant from the three largest meat companies and a second medium-sized or large plant which s laughtered either cows, bulls, boars, sows, veal, sheep or ritual. Three to four plants were visited in each city and plants which were closest to the airport were chosen. The ten secondary cities were either old stockyard cities or large metro areas which had sufficient plants.

The above list was used to randomly pick three cities from the primary list and two cities from the secondary list. To insure true randomness of selection, the cities were numbered and dice were used to chose the cities. The random selection procedure was conducted in the presence of a notary public on June 29, 1996 in Larimer County, Colorado. Only one Secondary city was visited because the other chosen city did not satisfy the criteria of having two large plants, due to an error in reading the published lists. All sixteen of the randomly chosen plants voluntarily agreed to participate in the survey provided that the data was presented in such a manner that specific plants could not be pinpointed as the sources of problems found in the surveys. The surveyed plants were very concerned about confidentiality because the list of the four cities visited was sent to the USDA and many people in the industry found out where the visited cities were located via the industry "grapevine". To further protect confidentiality, an additional eight plants were added. These plants were all plants which had called the author and requested visits during the survey period for various reasons. Due to the fact that the author was in these plants for other reasons it was not always possible to survey them for all of the items in the survey. The inclusion of these additional plants had little effect on the results of the survey. Overall the sixteen randomly chosen plants had slightly more problems than the eight additional plants.

To further protect confidentiality, plants were not given an identification number which was put on all of the data. Plant numbers on the data tables can not be cross referenced to plant numbers on other tables. Equipment descriptions in some instances are deliberately vague to prevent identification of the plant and exact line speeds will not be reported. It is the author's opinion that the pork plants included in this survey are very representative for the industry as a whole. Small and medium sized beef plants may be over represented and very large beef plants may be under represented.


Both objective data and subjective ratings were used to evaluate the plants. In most plants animals from more than one lot were surveyed. To make the observations more objective and random, there was no attempt to deliberately choose certain groups of animals for data collection.

Objective Scoring - with the exception of small plants. 100 to 200 animals in each plant were assessed for the following:

  1. Percentage of pigs and sheep where the electric stunner was placed in the wrong position.
  2. Percentage of cattle which had to be shot more than once with the captive bolt stunner.
  3. Percentage of sensible and partially sensible animals on the bleed rail.

A minimum of 50 animals in each plant were assessed for the following:

  1. Percentage of animals prodded with an electric prod.
    There were two separate tabulations of prod scores.

  2. Percentage of cattle and calves that vocalized in the stunning chute area. Vocalization induced by electric prods was tabulated.
  3. Percentage of cattle or pigs that vocalized or squirmed and became agitated in a restraining device or stunning box.
  4. Slipping and falling was also tabulated. In plants where there was obviously no slipping or falling, no formal data was collected. In plants with an obvious problem, data on slipping and falling was collected.
  5. Electric stunners were checked to determine if they delivered sufficient amperage to render the animals insensible.
  6. Captive bolt stun guns were checked to determine if they had sufficient hitting power to render the animals insensible with a single shot.

Subjective Ratings - Subjective ratings based on the author's twenty years of experience in handling animals were used to evaluate other areas of the plant's operation. Subjective ratings were also used in areas where objective data was collected.

Excellent - The educated (about slaughter practices) average person would accept it. Animals move quietly during handling.

Acceptable - Conforms to normal good industry practice.

Not Acceptable - A welfare problem that must be corrected.

Serious Problem - The problem must be corrected immediately because it is causing obvious signs of pain and distress.

The following areas received subjective ratings by the author.
  1. Behavior of plant employees handling animals in the stunning chute area.
  2. Behavior of plant employees handling animals in the yards, scale and unloading areas.
  3. Distractions that make animals balk such as air hissing, drafts, shadows, reflections, etc..
  4. Evaluation of electric prod equipment.
  5. Operation of powered gates.
  6. Maintenance and prevalence of bruise points in the stunning chute area, yards and unloading ramps.
  7. Pen stocking density in the stockyards.
  8. Availability of drinking water.
  9. Evaluation of the quality of vehicles arriving at the plant.
  10. Evaluation of the behavior of truck drivers handling animals during unloading. Up to 5 trucks in each plant were rated.
  11. Evaluation of handling of non-ambulatory animals.
  12. Condition of non-ambulatory animals.
  13. Prevalence of dead or stressed pigs.
  14. Condition of arriving animals.


Electric Stunning

Scientific research has shown that an electric stunner must have sufficient amperage to induce a grand mal seizure to insure that the animal will be made instantly insensible. For market weight pigs a minimum of 1.25 amps is required (Hoenderken 1982, Gregory 1988). For sheep a minimum of 1 amp is required (Gregory and Wotton 1984, Gilbert et al 1991). These amperages must be maintained for one second to induce instant insensibility. Insufficient amperage can cause an animal to be paralyzed without losing sensibility. The Council of Europe (1991) recommends the above minimum amperages. To insure sufficient voltage to deliver the amperage, 250 volts is the recommended voltage for pigs to insure insensibility (Troeger and Woltersdorf 1989). Research has also shown that too high of an electrical frequency will fail to induce insensibility. Warrington (1974) found that insensibility was most effectively induced at frequencies of 50 cycles. Frequencies at 2000 to 3000 hz failed to induce instant insensibility and may cause pain (Croft 1952, Van der Wal 1978). However, in pigs weighing under 200 lbs (80 kg) Anil and McKinstry (1994) found that high frequency1592 hz sinewave or 1642 hz square wave head only stunning at 800 ma (0.80 am p) would induce seizure activity and insensibility in small pigs. One disadvantage is that the pigs regained sensibility more quickly compared to stunning at 50 to 60 cycles. The pigs in this experiment weighed one third less than comparable U.S. market pigs and this probably explains why the lower amperages were effective. Some plants stun animals below the Council of Europe recommended minimum amperages in an attempt to reduce blood spots in the meat. Stunning market weight pigs with less than 1.25 amps should not be permitted (Grandin 1994a) unless different electrical parameters are verified by either electrical or neurotransmitter recordings from the brain. Since only a one second application at 1.25 amps is required to induce instant insensibility in market weight pigs, it is the author's opinion that plants should be permitted to use circuits which lower the amperage settings after an initial stun at 1.25 amps for pigs and 1 amp for sheep. Plants should also be encouraged to use electronic constant amperage circuits which prevent amperage spiking. Both practical experience and research has shown that these types of circuits greatly reduce petechial hemorrhages (Grandin 1985, Blackmore and Peterson 1981). Since U.S. market pigs are slaughtered at heavier weights compared to European pigs an electric stunner must deliver the minimum amperage recommended by the Council of Europe (1991) in order to be rated as either excellent or acceptable. It is the author's opinion that high frequency stunning should not be permitted in the U.S. until research is conducted to prove that it is capable of inducing an instantaneous grand mal seizure in heavier U.S. market weight pigs. In the Anil and McKinstry (1994) experiment, the pigs were stunned with a head only applicator. High frequency stunning has never been verified to induce instant insensibility when applied with a head to body cardiac arrest stunning electrode. This is the type of electrode used in almost all large U.S. pork slaughter plants. However, at the present time, pork plants should be permitted to use higher frequencies in their stunning cycle provided that the initial stun is a minimum of 1.25 amps at 50 to 60 hz for a minimum of one second.

Survey Results and Discussion for Electric Stunning

Eleven plants which used electric stunning were surveyed. Ten plants used cardiac arrest stunning on pigs held in a conveyor restrainer and one plant used head only stunning on animals standing on the floor. One pork plant had a stunner set at 0.75 amps for 250 to 275lb market weight pigs and this was rated as a serious problem. All other plants used sufficient amperage. Two plants used a Stork automatic stunner which uses over 5 amps. In four other plants with amperage meters the readings were 0.75, 1.25, 1.6 and 1.7 amps. The two automatic stunner plants and the three plants with meters reading 1.25 amps or more were rated as excellent. Four pork plants had voltage regulated commercially available stunners manufactured by Cincinnati Butcher's Supply Co. These stunners were rated acceptable because this unit usually applies more that 1.25amps. One sheep plant used an excellent imported New Zealand stunner which was state of the art and another plant used a stunner of unknown origin which was rated as acceptable because it was able to induce the spasm associated with a grand mal seizure in head only stunned animals. Observation of the spasms associated with a grand mal seizure can not be used to evaluate cardiac arrest stunning because stopping the heart masks the appearance of the seizure and an animal can appear properly stunned when it may possibly still be sensible ( Gilbert et al 1991). Therefore, it is the opinion of the author and other researchers that the only reliable way to evaluate stunning efficacy under plant conditions in cardiac arrested animals that appear to be well stunned is to carefully monitor electrical parameters such as amperage, voltage and waveform and to only use electrode positions and electrical parameters which have been verified with recordings from the brain (Grandin 1994, Gregory 1994, Cook 1992, Blackmore 1988). Research has clearly shown that the stunning electrodes must be positioned so that the electrical current flows through the brain (Croft 1952, Warrington 1974, Gregory 1988, Hoenderken 1982). When head to back or head to body cardiac arrest stunning is used one electrode must be placed on the head and the other can be placed at any point on the body. The head electrode must never be placed on the neck because this may result in a paralyzed but sensible animal (Gilbert et al 1991, Cook et al 1991). Placement of the head electrode in the hollow behind the animal's ear or on the forehead is recommended (Grandin 1994a, Hoenderken 1982). The head electrode can also be placed on the other parts of the head such as under the chin, top of the nose, or side of the head (Gregory 1992, Council of Europe 1991). The head electrode should never be allowed to slide back onto the neck. Electric stunning in 11 plants was evaluated for accuracy of stunner placement.

Placement Accuracy of Electric Stunner Electrodes
on Pigs and Sheep in Eleven Plants

 Animal Type
When Stunner
Rating Comments
Market Pigs 0% 0% 0% Excellent Well Maintained
Market Pigs 0% 0% 0% Excellent Well Maintained
Auto Stunner
Market Pigs 0% 0% 0% Excellent (1)
Sows 0.75% 0.75% 0% Acceptable
Market Pigs 1% 1% 0% Acceptable
Market Pigs 1% 1% 0% Acceptable
Market Pigs 2% 1% 2% Not Acceptable Operator Error
Market Pigs 2.6% 0% 4% Not Acceptable
Market Pigs 8% 10% 2% Serious Problem Poor Wand Design (2)
Sheep 47% 35% 0% Serious Problem Wrong Type Applicator (3)

100 to 200 animals were rated in each plant with the exception of 75 animals in one small plant. All animals were restrained in a conveyor restrainer except for one sheep plant. The prevelance of partially conscious pigs on the bleed rail was less than 1 per 1000 head. One pig with a righting reflex was observed during the survey in the plant which received a not acceptable score for operator error.

1. Sheep have a slightly more lenient criteria for placement because placement is more difficult.

2. It was difficult to hold the wand and prevent it from sliding out of position.

3. The sheep in this plant were stunned on the floor and the plant did not have a tong type applicator which could be clamped on the animal's head. The use of a tong-type applicator would make accurate placement possible.

One hundred to 200 animals were observed in each plant.

The cause of improper placement in one plant rated not acceptable was operator error and carelessness. Electrode applicator design was a major problem in the two plants rated a serious problem. It was extremely difficult for the operator to hold the electrode in the correct position during stunning. A more effective applicator can be either purchased or made in the plant maintenance shop for a few hundred dollars. Pigs vocalizing when the electrode is applied is caused by operator error. This occurs if the operator energizes the electrode before it is placed in full contact with the pig. The two plants with automatic stunners received excellent placement ratings because the equipment was very well maintained. However, if the electrodes are allowed to wear out or the system gets out of sequence, pigs may be stunned on the neck instead of on the head. In the Canadian Humane Slaughter Survey conducted in 1993 there were two plants with automatic stunners with worn out electrodes (Grandin 1993a). This resulted in pigs vocalizing and stunning on the neck. The electrodes on the Stork automatic Valhalla stunner must be adjusted so that they do not slide back on the neck during the stun.

Survey Results and Discussion of Captive Bolt Stunning

Eleven plants which used penetrating, captive bolt stunning on either cattle or calves were surveyed.

Efficacy of Captive Bolt Stunning On
Cattle and Calves in Eleven Different Plants

Animal Type Gun Type Percent
Rating Reason for Misses
& Comments
Fed Cattle Cartridge 0% Excellent Both plants had a shelf to hold the bovine's head up.
NOT a full restraint head holding device.
Formula Veal Pneumatic 0% Excellent
Cows Pneumatic 5% Acceptable Cattle stayed still. Well maintained gun.
Cows Pneumatic 5% Acceptable Cattle stayed still and held heads up.
Cows Pneumatic 9% Not Acceptable Poor maintenance of gun trigger.
Cows Cartridge 11% Serious Problem Poor maintenance. Insufficient Hitting Power.
Fed Cattle Pneumatic 12% Serious Problem Gun Ergonomics. Aiming Problem.
Fed Cattle Pneumatic 14% Serious Problem Poor maintenance of gun trigger.
Cows Pneumatic 14% Serious Problem Animal movement due to slipping in stun box.
Fed Cattle Pneumatic 15% Serious Problem Gun ergonomics. Aiming Problem.
Cows Cartridge 20% Serious Problem Poor maintenance. Gun had insufficient hitting power.

Data in Table 3. does not include bulls. Observed 17 bulls in two different plants; 4 head missed due to ergonomics or gun misfiring. In 9 plants, 100 to 200 cattle were rated and in 2 small plants a smaller number of animals were rated. Comparison of plants under 100 head per hour and plants over 100 head per hour resulted with large plants with 8% missed (N=4 plants), small and medium sized plants with 10.4% missed (N=7 plants). Incidence of partially conscious cattle on the bleed rail was approximately 1 per 1000 (Rating: Excellent). In the 9 largest plants, 100 or more animals were rated for stunning insensibility on the bleeding rail.

Three plants (27%) used cartridge fired stun guns and the rest used pneumatic stun guns. In seven plants (64%) a well maintained stun gun had sufficient hitting power to induce insensibility with one shot. In four plants (36%) the guns were poorly maintained and failed to hit with sufficient power, due to either lack of servicing of the internal parts or a malfunctioning triggering device on a pneumatic stunner. These malfunctions resulted in an animal being hit with partial force. The two other causes of missed first shots were animals moving or poor gun ergonomics.

In one plant the balancer on the pneumatic stunner was so poorly designed and the gun was so bulky and heavy that the author did not have sufficient strength to operate it. In this plant the percentage of missed first shots was 15%. The stunner operator in this plant was a large strong man but the effort required to operate this gun produced a large swollen spot on his hand. This plant was able to raise their one shot efficacy score to better than 99% after they made ergonomic improvements on the gun such as a handle extension and a better balancer system. They also improved maintenance procedures and modified the gun so that it now has a longer bolt.

The manufacturers of pneumatic stun guns must address the problem of poor gun ergonomics. Six plants (54%) were rated a serious problem with the percentage of missed shots ranging from 9 to 20%. Two plants (18%) rated excellent for stunner efficacy with 100% shot on the first shot. The author has observed that gun ergonomics has not improved during the last twenty years. In fact it may have become worse with the introduction of stunners configured in a manner similar to pneumatic nailing guns. The old pneumatic stunners which were popular twenty years ago were easier to operate because they had a long handle and a slender configuration. Over the years, the author has observed that stunning first shot efficacy in plants using a well maintained cartridge fired hand held stunner was often way above the average 90.5% first shot efficacy for the eleven surveyed plants. In both large and small plants, the author has stunned over 95% of the cattle on the first shot with a well maintained cartridge fired stunner.

Unfortunately it was not possible to conduct a comparison of pneumatic and cartridge fired stunning in one of the surveyed plants because their backup hand held cartridge stunners were poorly maintained. Plants with chain speeds of over 100 per hour averaged fewer missed shots (7.4%) compared to plants with chain speeds under 100 animals per hour which averaged 11.3% missed shots. In one plant animal movement due to slipping on a slick stunning box floor was a major problem. This can be easily fixed by installing a floor grating of metal bars to stop slipping. In two plants with 100% stunning accuracy the heads of cattle and veal calves were held up with the forehead parallel to the floor by a shelf in the front of the stun box. A rear pusher gate held the cattle in position, and people held the veal calves. The pusher gate resulted in improved accuracy but it may have caused increased stress because some cattle vocalized. In the veal plant there was no vocalization or struggling and the system worked well. In plants with conveyor restrainers, lights can be used to induce cattle to raise their heads. In plants which were not included in this survey the author has observed approximately 99% one shot stunning efficacy in properly lighted conveyor restrainer systems and stunning boxes operated by skilled people. Over the last twenty years the author has observed that well maintained cartridge fired hand held stunners usually have higher first shot efficacy rates than bulky pneumatic stunners with poor ergonomics.

Stunning Conclusions and Recommendations

Overall, electric stunning had fewer problems than captive bolt stunning. Problems with electrode placement can be easily fixed by using a different applicator at minimal cost. The author concludes that the 11 surveyed plants as a group should receive a subjective rating of acceptable for electric stunning. Only one plant out of the 11 surveyed plants used insufficient amperage. Plants should be required to use a minimum of 1.25 amps for market weight pigs and 1 amp for sheep. Several plants have already installed computerized monitoring systems for monitoring the quality of electric stunning. The use of this technology should be encouraged.

However captive bolt stunning needs major improvement because slightly over half of the surveyed plants missed m ore than 10% of the cattle on the first shot and were given a serious problem rating. Poor maintenance was a major cause of failed first shots. The ergonomics of pneumatic stun guns needs to be improved because some of these guns require too much effort to operate. In some cases ergonomics can be improved with simple inexpensive changes such as installing a handle extension. This enables the operator to hold the handle with both hands. An improved balancer can easily be made by putting the gun on a counter weight instead of using a spring type balancer. To facilitate positioning of the gun, the balancer or counter weight pulley should be located 8 feet above the animal's head. A counter weight provides the advantage of not increasing tension when the operator has to move the gun downward to reach the animal. The author estimates that in most plants stunning first shot efficacy could be brought up to an acceptable 5% miss rate with simple inexpensive improvements and better gun maintenance.


The twenty two surveyed plants did extremely well in bleeding rail insensibility and the group as a whole would be given a subjective rating of excellent. Employees in most plants made sure animals were insensible before they were hung on the bleeding rail. Only one possibly sensible pig was observed out of over 1000 pigs scored in eleven plants. This pig was observed in the plant which received a not acceptable rating for a 2% rate of incorrect electric stunner placement. The cause of the one possibly sensible pig was stunner operator error. This pig displayed a righting reflex while hanging on the rail and had a curled tongue. Eye reflexes were absent and it was not vocalizing. It is highly probable that this pig was not sensible. All other pigs in this plant displayed no signs of return to sensibility. In over 1000 cattle and calves scored in eleven different plants only one beef animal was hung on the shackle that appeared to be fully sensible. It was immediately shot with a cartridge fired stunner. This animal may have occurred because the stunner operator was nervous and trying to achieve a good one shot efficacy score. In all of the plants surveyed there was a zero incidence of sensible animals being cut on or going into the scald tank.

Many people are confused on how to determine if an animal is insensible. An insensible animal's legs will often kick. This is just reflexes and in electrically stunned animals it may be a spasm induced by the seizure. For additional information refer to Gregory (1988), Blackmore and Newhook (1982), and Grandin (1994a).

After an animal is hung on the rail it must not have any of the following signs:
  1. Rhythmic breathing
  2. Vocalizations
  3. Eye reflexes in response to touch
  4. Blinking
  5. Arched back righting reflex. The back must be straight and the head should hang down and be floppy. If the animal arches its back it is attempting to right itself.
Gasping is permissible because it is the sign of a dying brain (Gregory 1988).
If the tongue is hanging straight out and is limp the animal is definitely insensible.

Twenty-two plants were evaluated for the incidence of animals slipping and falling in the stunning chute area.

Prevelance of Slick Floors Causing Animals to
Slip or Fall in the Stunning Chute Area

Species Number
of Plants
% of Animals
That Slipped
% of Animals
That Fell
Slipping Rating Comments
Pork 9 0% 0% Accept./Excell. Most had good non-slip floor in the stunning area; and quiet handling.
Sheep 2 0% 0% Accept./Excell. Quiet handling.
Cattle & Calves 6 0% 0% Accept./Excell. 3 out of 6 plants had very quiet handling.
Cattle & Calves 1 3% 0% Acceptable Animals slipping in stunning box.
Cattle & Calves 1 15% 0.5% Serious Problem Animals slipping in stunning box.
Cattle & Calves 1 20% 0% Serious Problem Animals slipping in stunning box.
Cattle & Calves 1 22% 12% Serious Problem Crowd pen as smooth as glass.
Cattle & Calves 1 30% 8% Serious Problem Animals slipping in stunning box.

In cattle and calf plants, 4 plants (36%) had serious problems with slipping and falling in the stunning chute area. All pork and sheep plants (100%) were either excellent or acceptable for slipping in the stunning chute area.

Quiet calm handling where animals move with a minimum of visible agitation is impossible if the handling facilities have slick floors. Non-slip flooring in unloading ramps, yards and stunning areas is recommended by Grandin 1991, Stevens and Lyons 1977. In a plant where 38% of the cattle slipped, cortisol levels were 63 ng/ml (Cockram and Corley 1991). In comparison, plants with less electric prod usage and quieter handling had average cortisol levels of 24 ng/ml (Ewbanks et al 1992), 32 ng/ml (Mitchell et al 1988),and 44 ng/ml (Tume and Shaw 1992). It is the author's opinion that non-slip flooring is one of the minimum facility requirements to maintain good animal welfare.

Eleven pork and sheep plants had no measurable slipping in the stunning chute area and they were all rated acceptable or excellent. There were major slipping or falling problems in 4 (36%) of the plants slaughtering cattle or calves (Table 4). Four (36%) of beef plants were given a rating of serious problem. Slipping in the stunning box occurred in four plants. In two plants 12% and 8% of the animals fell down in the stunning area. In the author's opinion this caused a serious welfare problem. Slipping in the stunning box can be easily fixed in most plants by installing a grating of one inch steel bars in a 12 inch square pattern on the stunning box floor. In two plants cattle slipped and became agitated when one leg slipped off the stun box floor into the shackle area. This problem can be easily corrected by installing a toe guard to prevent the animal's feet from slipping off the platform. Plant maintenance departments can easily modify the stunning box floor and the cost would only be a few hundred dollars.

Table 5 shows the prevalence of slipping in the plant yards and unloading areas.

Rating of Slick Floors Causing Animals to Either
Slip or Fall in the Yards and Unloading Area

Species Number of Plants Surveyed Excellent Non-
Slip Floors
Acceptable Not Acceptable Serious Problem Comments
Pork 9 3 (33%) 3 (33%) 2 (22%) 1 (11%) In two plants, pigs fell down.
In the serious problem plant pigs were unable to walk down the unloading ramp without slipping or falling.
Sheep 2 0 2 (100%) 0 0
Cattle & Calves 10 5 (50%) 3 (30%) 2 (20%) 0 In the two plants with not acceptable floors, the grooves in the drive alley were worn out.

Eight (38%) of 21 plants surveyed had excellent non-slip flooring in either a new or a well maintained older facility. Ratings of either excellent or acceptable were given to six pork plants (66%) and both sheep plants. Out of 10 plants, slaughtering cattle and calves, 8 plants (80%) were rated with excellent or acceptable for slipping in the yards. One pork plant had a serious problem with a slick unloading ramp which caused many pigs to slide and fall down. This problem can be corrected by installing bigger cleats on the ramp. In three plants the grooves in the main drive alley were worn smooth. Five plants (23%) received a rating of either not acceptable or serious problem for slick floors. Overall problems with slick floors in the yards and unloading area were less serious from a welfare standpoint than slipping and falling problems found in cattle stunning boxes. In all of these plants the floor in the yards could be easily regrooved with a rented grooving machine or have a concrete cap poured on the drive alleys of quick drying concrete mix. A high standard of animal welfare is easily attainable in older facilities if a non-slip finish is maintained on the floors.


Twenty-two plants were rated on the behavior of plant employees who were stunning and handling animals.

Ratings of the Behavior of Handlers in the
Stunning Chute Area of 22 Plants

Handling Rating Number of Plants Percentage of
Surveyed Plants
Excellent 13 59% Animals were handled quietly with a minimum of electric prodding.
Crowd pen filled 1/2 to 3/4 with cattle or pigs.
Acceptable 4 18% Handling at an acceptable industry standard.
Not Acceptable 3 14% At one plant, a killfloor foreman excessively prodded pigs and handled them roughly.
In all three plants, either the crowd pen or staging area were overloaded.
Serious Problem 2 9% Plant 1: Killfloor foreman excessively prodded cattle, 32% of the cattle vocalized.
Plant 2: Electric prods were used to paralyze cattle to hold them still for stunning.

All plants were rated either acceptable or excellent handling in the yards. The three serious problem plants all had excellent yard handling.

Seventy-seven percent of the plants received either excellent or acceptable ratings for handling in the stunning chute area. The survey was announced so people tended to be on their best behavior. Two plants (9%) were rated not acceptable for handling in the stunning area because they overloaded either the crowd pen or the staging area with too many animals. This caused the animals to become visibly agitated. The plants which had the quietest handling filled their staging areas and crowd pen only one half to three quarters full and moved small groups of animals. Animals need room to turn. Further information on handling principles can be found in Grandin (1991, 1993, 1996).

The author observed extremely rough handling in two plants (9%) and rated them a serious problem. In one of these plants an electric prod was used to paralyze cattle to hold them still during stunning. Immobilizing an animal with electricity is extremely aversive (Grandin et al 1986, Lamboy 1985, Pascoe 1986, Rushen 1986). It is the author's opinion that the use of electricity to immobilize sensible animals is a practice which must be forbidden. In two plants a kill floor foreman and a lead man handled pigs and cattle roughly and prodded numerous animals with an electric prod. In both of these plants the foreman engaged in excessive prodding after the author had shown the employees how to move the animals in smaller groups with less prodding. Interestingly, the three plants with the worst handling in the stunning area had excellent handling in the yards and unloading area. All plants surveyed had either excellent or acceptable handling practices in the yard areas which were located away from the stunning area. Out of 19 plants 84% had excellent yard handling and 16% had acceptable yard handling. None of the plants were given a not acceptable or serious problem rating for yard handling.

A very clear pattern emerged of employee behavior. Yard employees who were supervised by the livestock procurement department handled animals more gently and quietly than stunning chute area employees who were supervised by the slaughter department. The three worst behaved employees observed during the entire survey were a kill floor foreman, a kill floor lead man, and a beef stunner operator. In these three plants the stunning chute area was very poorly supervised compared to the excellent handling by yard employees. During a twenty year career, the author has observed that handling in the plant yards and unloading area has improved to a greater extent than the handling in the stunning chute area. Another observation is that the plants which have the best handling in the stunning area have a strong manager who insists on considerate handling of animals (Grandin 1988, 1994a). In several publications the author has written that the manager who is most effective in supervising employees who handle thousands of animals must be involved enough to care but not so involved that he or she becomes numb or desensitized (Grandin 1994a).

The most effective supervisor is either a superintendent, USDA Veterinarian in Charge or the plant manager. This person strictly enforces good handling and stunning practices. In plants with good handling, the employees know that they will be fired for animal abuse (Grandin 1988). Both during this survey and in visiting other plants, the author has observed that kill floor foreman often participate in rough handling.


In both older facilities and new state-of-the-art facilities the chutes and other equipment must be free of distractions which cause balking and impede animal movement (Grandin 1996). Distractions such as ventilation air blowing in the face of approaching animals makes it extremely difficult to quietly move them. Lighting mistakes, shadows, reflections, air hissing and high-pitched noises can ruin performance of the best chute systems. The prevalence of distractions which caused balking was rated in nineteen beef and pork plants. Ten plants (55%) were free of distractions which caused balking in the stunning chute area (Tables 7 and 8). Three of the nine plants that were rated excellent had older facilities.

Table 7.
Distractions Which Caused Pigs to Balk in the Stunning Chute and
Crowd Pen, Which Caused Increased Usage of Electric Prods
Type of Animal
of Distraction
Rating Comments
Market Pigs None: Very quiet, low machinery noise. Excellent Animals moved easily through chutes.
Market Pigs None Excellent " "
Market Pigs None Excellent " "
Market Pigs None Excellent " "
Sows Seeing people moving and possible reflections Acceptable Caused some slowing of the animals.
Market Pigs Noise from ventilation fans increased as pigs approached the stunner. Acceptable Caused some slowing of the animals.
Market Pigs Seeing people moving and chains hanging in chutes. Not Acceptable Seeing movement caused pigs to stop.
Market Pigs Shiny reflections Not Acceptable
Market Pigs Shadows and reflections
The staging area was much brighter than the stunning chute. This caused the pigs to turn back towards the light.The problem was worse when bright sun was shining.
Serious Problem Made quiet handling and reduction of electric prod use impossible, because the pigs kept turning back.

None of the plants had ventilation air blowing into the faces of approaching animals. This will usually cause balking. Plants with no distractions had worked to eliminate them prior to being surveyed. Ratings of nine pork plants for distractions were 44% excellent, 22% acceptable, 22% not acceptable, and 11% a serious problem.

Table 8.

Distractions Which Caused Cattle and Calves to Balk in Stunning Chute and Crowd Pen, Which Increased Use of Electric Prods

Type of Animal Description of Distraction Rating Comments
Fed Cattle None Excellent Animals moved easily through the chutes.
Fed Cattle None Excellent " "
Cows None Excellent " "
Fed Cattle None Excellent " "
Fed Cattle None Excellent " "
Veal None Excellent " "
Fed Cattle Air hissing from control valve exhaust. Not Acceptable Made cattle balk.
Cows Air hissing from control valve, reflections, seeing movement under stun box door. Not Acceptable Made cattle balk. Screeching from saw also caused agitation.
Fed Cattle Bright sunlight caused shadows in the crowd pen. Air hissing from control valve, high pitched whistling from a pump. Not Acceptable Made cattle balk.
Cows Air hissing from control valve, seeing movement under stun box door. Serious Problem Made cattle balk, impossible to lower prodding score.

None of the plants had ventilation air blowing into the faces of approaching animals. This will usually cause animals to balk. All plants with no distractions had worked to eliminate them prior to being surveyed. Ratings 60% excellent, 30% not acceptable, and 10% serious problem.

In two plants (9%) distractions were sufficiently severe so that handlers had to constantly prod animals that either balked or turned back. In one beef plant cattle refused to enter the stunning box because they could see people moving under the stun box door. This problem could be easily corrected by installing a rubber flap on the bottom of the door to block the animal's vision of the movement. In the pork plant pigs refused to enter the crowd pen because the staging area was in bright sunlight.. This facility worked well when it was cloudy but poorly when the sun was out. The problem was corrected by installing metal siding on a building which had open sides. Minor balking problems can often be fixed by moving a light to eliminate a sparkling reflection. Pig movement was improved in one plant by covering a portion of the top of the stunning chute to eliminate glistening reflections on the wet floor of the chute.

Air hissing from control valves caused balking in 4 (33%) of the surveyed beef plants. This problem can be easily fixed by piping control valve exhausts outside or installing inexpensive mufflers. The mufflers have to be replaced every few months when they stop working due to clogging with dirt. Elimination of air hissing will also greatly improve the working environment for plant employees.


Table 9 shows electric prod use in eight plants which had well trained employees who only used an electric prod on animals that stopped moving.

Table 9.

Electric Prod Scores for Eight plants With Well-Trained Handlers Who Only Prodded Animals That Balked (Baseline Percentages)

Beef % of Cattle Prodded Comments
Plant 1 5% (**) No electric prods in crowd pen or yards, prod used at restrainer or stun box entrance only.
Plant 2 10% (**) " "
Plant 3 10% (**) " "
Plant 4 64% (*) Cattle could see movement and the feet of shackled cattle under the stun box door.
4 Plants: 2 large and 2 medium sized.

Pork % Prodded at Restrainer Entrance % Prodded in the Crowd Pen Comments
Plant 1 6% 18%
Plant 2 19% 18%
Plant 3 15% 0%
Plant 4 28% 80% (*) Major lighting problem caused pigs to turn back. The pigs refused to move forward into a darker area.
4 Plants: 3 large and 1 small sized.

(*) Problems with animals seeing movement and lighting made it impossible to achieve an acceptable prod score in two plants.

(**) In the three beef plants with the lowest prod scores, a stick with plastic streamers attached or a light whip was used. There was no whip cracking.

Six of the eight plants in Table 9 were relatively free of major distractions which caused cattle and pigs to balk. The three cattle plants with minimal distractions had an average prodding score of 8.3% of the cattle at the restrainer or stunning box entrance and no prods were used in the crowd pen. In three relatively distraction-free pork plants an average of 13.3% of the pigs were prodded at the restrainer entrance and 11% of the pigs were prodded in the crowd pen. Three out of six (50%) of the plants with low prodding scores had older facilities and the beef plant with the lowest prodding score had a new modern facility. In two plants the distractions discussed previously made it impossible to reduce electric prodding and still keep up with the processing line. In these two plants the employees had to prod an average of 72% of the animals to keep the line full. This data clearly shows that prod use can be reduced to a very low level. However, it is not possible to completely eliminate electric prods and still keep up with the processing line.

Table 10: Reduction in Electric Prodding After Handling Training in Four Plants With Previous High Electric Prod Percentages

Species Prodding Baseline Prodding After Handling Training Distractions
Beef 90% (Estimate) 14% Air Hissing
Beef 76% 20% High Pitched Noise
Pork 48% 15%
Pork 40% 15%
MEAN 63% 16%
Beef 34% 4%
Pork 68% 24% Removed chain hanging in chute.
Pork 52% 13%
MEAN 52% 14%

In all four plants it was possible to keep up with the line at reduced prodding rates. A minimum of 50 animals were scored for the baseline. After handling training, an additional 50 animals were scored.

Table 10 shows electric prod usage in four beef and pork plants where the employees engaged in excessive prodding. Two of these plants were rated a serious problem for allowing employees to handle animals in an abusive manner. In the beef plant with the 90% prodding estimate they were not formally prod scored for baseline prodding rates because the author stopped the exceedingly rough abusive treatment of the cattle. In the other three excessive prod plants a 50 head baseline was scored. Table 10 clearly shows that prodding was greatly reduced in the stunning chute from an average of 63% of the animals to an average of 16% after the author briefly showed the employees how to move smaller groups of animals. The employees were also instructed to attempt to move an animal by tapping its rear before resorting to an electric prod. Prodding in the crowd pen was reduced from an average of 52% to 14%. The Chi square statistic was done in the three plants with tabulated prodding scores and it was significant to the <.001 level. The slaughter line was kept full when electric prodding was reduced. Even though three plants had distractions of air hissing, chains hanging in the chute and high pitched noise they were able to greatly reduce prodding. In all four plants employees were able to easily keep up with the line at reduced prodding rates.

Table 11: Evaluation of Electrical Prods in 21 Plants

Type of Electric Prod Rating Number of Plants Percent of Plants Surveyed Comments
None Excellent 4 19% Processed sheep, veal, or non-ambulatory cattle. A goat led the sheep in one plant. Handling excellent in all four plants.
Very weak electrical prods caused only 1% of the animals to vocalize when prodded once. Excellent 3 14% In both the pork plant and and the two beef plants, the employees were able to keep up with a high speed line. All three plants had a minimum of distractions which would cause balking. These plants were not prod scored because prod scores would be meaningless from an animal welfare standpoint.
Battery operated or wired in prods, which cause vocalization only if held on an animal. A single tap will not cause vocalization. Acceptable 7 33% In four beef and three pork plants, all were rated either excellent or acceptable handling. Handlers kept up with the processing line.
Prods with sufficient strength to cause many animals to vocalize when prodded only once; capable of knocking an animal down or paralyzing it. Serious Problem 7 33% Three of these plants had very rough handling in stunning area. One plant used prods to paralyze cattle in order to keep them still for stunning.

Table 11 outlines the type of prods that were used in 21 plants that were rated for prod type. The sheep, veal and non-ambulatory cattle plants did not use prods. None of the plants allowed plant employees to use electric prods in the yards. Prod use was confined to the stunning chute area. Three (14%) plants had such weak prods that it was pointless to prod score them because they were almost dead sticks. In one of these plants the prods were broken and in another plant the author could not feel anything when she held the end of the prod.

Electric prod equipment was subjectively rated as excellent if prodding an animal briefly caused vocalization in 1% or less of the animals. Battery operated prods which deliver a shock to a small localized area between two prongs were rated acceptable. Prods connected to an overhead wire were rated acceptable if a single brief tap did not cause vocalization. Seven plants (33%) were given a serious problem rating because they had prods which caused many animals to vocalize when prodded only once. Attempts to evaluate electric prods by looking at an electric meter were often useless. There was often little relationship between meter readings and animal reactions due to variables such as wetness of the floor. In one plant the author observed a low meter reading on a prod which caused a very strong reaction and frequent vocalizations from the animals. This was a homemade electric prod power source and the meter was probably a fake meter to impress the inspector. Most prods wired to an overhead wire had a transformer in the circuit but in two plants a dangerous light bulb wired in series to 120 volt AC was used. In both of these plants the light bulb in series caused many pigs and cattle to vocalize. In another plant a homemade power unit created a large spark that made pigs squeal. The best systems used a low voltage circuit with a transformer. Four (19%) pork and beef plants used a 20 to 24 volt transformer with an accurate meter. Two of these systems were purchased from a commercial supplier.

The author recommends the use of commercially available power sources for prods or the use of battery operated prods.


Research with pigs has shown that intensity of pig vocalization is correlated with physiological measures of stress (Warris et al 1994). Preliminary research by Bridgett Voisinet at the author's laboratory at Colorado State University has shown that the number of times that cattle vocalize during a stressful husbandry procedure is related to cortisol (stress hormone) levels. The overall intensity of pigs squealing can be used within a plant to assess handling stress. The quieter the pigs the lower the stress. Observations of handling of pigs in the surveyed plants indicated that squealing was lower in plants with quiet handling. Squealing in pigs can not be compared accurately between plants because it is very difficult to tabulate individual pig squeals in the staging area, crowd pen and chute. Pig squeals in the restrainer were tabulated.

Table 12: Baseline Vocalization Scores During Handling for Cattle and Calves in the Stunning Area and Crowd Pen in 8 Plants

Cattle Type Number Rated Number Vocalized Percent Vocalized Rating Comments
Fed Cattle 200 0 0% Excellent Quiet handling in small groups.
Formula Fed Veal 150 0 0% Excellent Quiet handling.
Cows 175 2 1% Excellent Quiet Handling.
Cows 150 4 2.6% Acceptable Quiet handling. Vocalization of three animals in direct response to prodding.
Cows 150 10 6.6% Not Acceptable Eight cows direct response to prodding. One cow slipped. Cattle balked and refused to enter stun box due to seeing movement under discharge door.
Fed Cattle 200 15 7.5% Not Acceptable Slipping in stun box, excessive pressure applied by restraint device.
Fed Cattle and Cows 100 12 12% Serious Problem Rough handling, paralyzing cattle with electric prod.
Fed Cattle and Cows1 175 5 32% Serious Problem Rough handling, 2/3 of vocalizations in direct response to prodding, 1/3 due to excessive pressure from restraint device.
Holsteins1 20 7 35% Serious Problem This breed too long to fit in restraint device, excessive pressure.

1 Same Plant

Vocalizations of cattle are easy to tabulate and data in Tables 12 and 13 show how the percentage of vocalizations was related to the gentleness of handling. In the two beef plants with the roughest handling, vocalization scores were tabulated (Table 13a).

Table 13A: Reductions in Vocalizations After Rough Handling Was Stopped in the Two Beef Plants With the Highest Vocalization Scores

Rough Handling Baseline Improved Handling

Number Rated Vocalizing Animals Percent Vocalizing Number Rated Vocalizing Animals Percent Vocalizing
Plant 1 100 12 12% 100 3 3%
Plant 2 175 56 32% 75 10 13%


7% P<0.001

Explanation of vocalizations in improved handling groups:

Plant 1 - All vocalizations in direct response to prodding when cattle balked.
Plant 2 - Most vocalizations in direct response to prodding when cattle balked at air hissing.

The percentage of cattle which vocalized declined from an average of 22% to 7% when rough handling and excessive use of electric prods was stopped. The Chi square statistic was significant at the <.001 level. The two rough handling plants were also compared to four other beef plants which had well trained handlers and fully tabulated prod data (Table 13b).

Table 13B: Comparisons of Vocalizations in Cattle Between the Two Roughest Plants and Four Other Beef Plants Which Had Quiet Handling

Rough Beef Plants Quiet Handling Beef Plants

Number Rated Vocalizing Animals Percent Vocalizing Number Rated Vocalizing Animals Percent Vocalizing
Plant 1 175 56 32% 200 15 7.5%
Plant 2 100 12 12% 150 4 2.6%
Plant 3

150 10 6.6%
Plant 4

175 2 1%



The percentage of cattle that vocalized was 22% in the two rough plants and only 4.5% in the four plants with well trained employees. The Chi square statistic was significant at the <.001 level. This data clearly shows that excessive prodding and rough handling significantly increased cattle vocalizations.

The author has observed in very large plants which were not in this survey that careful handling of cattle results in low vocalization rates of 1% or less in the stunning chute area. Cattle vocalization scores remained relatively high (mean = 4.5%) in the best surveyed plants due to problems with a restraint device, excessive distractions which caused balking and slick floors. When cattle vocalizations are tabulated during handling in the stunning chute area only vocalizations occurring in the crowd pen, lead up chute, restrainer or stunning box should be tabulated. Cattle standing quietly in the yards will often vocalize to each other and vocalize due to hunger. In one plant hungry Holsteins vocalized and turned to face a man bedding a pen with sawdust. It appeared that they perceived the sawdust as feed. Observations at one of the sheep slaughter plants indicated that vocalization during handling is absolutely useless as a measure of handling problems in sheep. Sheep walking quietly up the stunning chute the sheep vocalized to each other. Sheep which balked and had to be pushed by a person never vocalized. This is a species difference between cattle and sheep.

Vocalization in Restraint Devices

Vocalization in both pigs and cattle is a useful measure of discomfort caused by restraining devices. Observations in the surveyed plants indicated that both pigs and cattle were more likely to vocalize in a restraining device if they became agitated and squirmed and struggled against the device (Tables 14 and 15).

Table 14: Vocalization and Agitation Scores for Pigs During Restraint in a Conveyor Restrainer

Animals Percent Vocalized Percent Agitated Rating Reason for Vocalizing
Market Pigs 0% 0% Excellent V restrainer; quiet handling
Market Pigs 0% 0% Excellent V restrainer; auto stunner
Market Pigs 0% 4% Excellent V restrainer
Sows 2% 5% Acceptable Bigger animals quieter
Market Pigs 1% 8% Acceptable V restrainer
Market Pigs 0% 18% Acceptable V restrainer, auto stunner. Slender animals struggled after transferring from one conveyor to the next.
Market Pigs 14% 8% Not Acceptable Not Many animals squirmed and Acceptablestruggled when they were transferred from one moving conveyor to the next due to missing rollers.

A minimum of 50 animals were scored. Sheep were not rated because vocalization scores are meaningless for sheep.

The major causes of vocalization or agitation were due to the animal not being fully supported by the conveyors or improperly adjusted or maintained transfer points between two moving conveyors.

Table 15: Vocalization and Agitation Scores for Cattle During Restraint in Either a Conveyor Restrainer or Stunning Box During Conventional Slaughter

Animals Percent Vocalized Percent Agitated Rating Restraint Equipment
Fed Cattle 0% 0% Excellent Conveyor Restrainer
Fed Cattle 0% not scored; est. low Excellent Conveyor Restrainer
Fed Cattle 0% 0% Excellent Stunning Box
Formula Veal 0% 0% Excellent Stunning Pen
Cows 0.6% 0% Excellent Stunning Box
Fed Cattle 7.5% 7.3% Not Acceptable Stunning Box
Cattle slipping on floor, excessive pressure from devices pressed against animal.
Cows 0.6% 40% Serious Problem Stunning Box
Cattle slipped on floor.
Fed Cattle & Cows 6% 7% Serious Problem Stunning Box
Vocalized in direct response to being paralyzed with a prod to make them stand still; prodding also made them fall down.

A minimum of 50 animals were scored in each plant. Vocalization induced by electric prodding which occurred outside of the stunning box or restrainer was subtracted.

The reaction of pigs and sows to a V restrainer conveyor was tabulated in seven plants. In 4 plants (57%) of the plants pigs did not vocalize in the V restrainer. Only one restrainer (12.5% ) of the plants surveyed was rated not acceptable because 14% of the pigs vocalized. This was due to missing transfer rollers in a two speed dual conveyor system where the pigs are transferred from a slower conveyor to a faster one. This system is used to index and separate pigs for automatic stunning. Observations both in the surveyed plants and in plants in Europe indicated that very slender pigs tend to struggle more in a V conveyor restrainer than round fat pigs (Grandin 1993). Changing the angle of the conveyor sides may help correct this problem. Pigs will settle down in a restraining conveyor if it is adjusted to fully support their bodies without pinching.

Vocalization and agitation scores for beef cattle and veal calves held in stunning boxes and conveyor restrainers is shown in Table 15. Observations were made in eight plants. Five plants (62%) were rated as excellent. Two of these plants had conveyor restrainers and three had stunning boxes. Two plants (25%) were rated as having a serious problem due to either high vocalization or agitation scores. The major causes of cattle discomfort was slipping on the stunning box floor which caused the animal to become agitated. In one plant electricity from a prod was used to immobilize cattle to hold them still for stunning. It is the author's opinion that immobilizing fully sensible animals with electricity is a practice that should be forbidden. Several research studies have clearly shown that it is highly aversive (Grandin et al 1986, Pascoe 1986, Lambooy 1985, Rushen 1986). The use of head restraint device can improve stunning accuracy. However, poorly designed head restraint may increase stress. Ewbank et al (1992) reported that cortisol levels were significantly higher compared to a standard stunning box. In this poorly designed system up to 30 seconds and numerous prods were required to induce cattle to enter the device.

In the author's survey the two plants which had 100% one shot stunning efficacy scores used a stunning box which prevented the animal from putting its head down. It was not a full head restraint like the type used for ritual slaughter. One beef plant used a shelf to restrict downward movement of the animal's head. The cattle quietly entered the box with one tap from a very weak electric prod. Cattle never vocalized during entry. The major problem with this restraint device was slipping on the stunning box floor which caused agitation.

Excessive pressure applied to the animal by a rear push gate was probably responsible for one third of the vocalizations, and slipping on the floor was the cause of approximately two-thirds of the elevated vocalization and agitation scores. Problems with this device can be easily fixed by installing non-slip flooring and reducing the pressure. The author believes that making these inexpensive changes would almost eliminate agitation and vocalization. In several different publications the author has outlined the behavioral principles of low stress animal restraint (Grandin1991,1993,1994, 1995). The basic principles of low stress restraint which will minimize vocalization and agitation are:

  1. For cattle, block the animal's vision so that they do not see people or suddenly moving objects. Install metal shields around the animal's head on box type restrainers. This is not necessary on conveyor restrainers.
  2. Block the animal's vision of an escape route until it is fully held in a restraint device (Grandin 1991). This is especially important on restrainer conveyors. Cattle often become agitated in conveyor restrainers if they can see out from under the hold-down cover before their back feet are off the entrance ramp. Extending the solid hold down cover on a conveyor restrainer will usually have a calming effect and most cattle will ride quietly. Solid hold downs can also be beneficial for pigs on convey or restrainers.
  3. Eliminate air hissing and other distractions such as clanging and banging. Refer to section on distractions.
  4. The device must be properly lighted. Animals will not enter a dark place or enter a place where direct glare from a light is blinding.
  5. Provide non-slip flooring in box-type restrainers and a non-slip cleated entrance ramp on conveyor restrainers. Animals tend to panic when they lose their footing.
  6. Parts of a restraint device that press against the animal's body should move with slow steady motion. Sudden jerking motion excites animals. On existing equipment install inexpensive flow controls to provide smooth steady movement of moving parts which press against the animal.
  7. Use the concept of optimum pressure. The restraint device must apply sufficient pressure to provide the feeling of being held but excessive pressure that causes pain should be avoided. Install a pressure regulator to reduce the maximum pressure that can be applied. Very little pressure is required to hold an animal if it is fully supported by the device. If an animal bellows or squeals in direct response to the application of pressure the pressure should be reduced.
  8. A restraint device must either fully support an animal or have non-slip footing. Animals panic if they feel like they may fall. Restraint devices should hold fully sensible animals in a comfortable, upright position.
  9. Equip restraint devices with controls that enable the operator to control the amount of pressure that is applied. Different sized animals may require differing amounts of pressure. Hydraulic or pneumatic systems should have controls which enable a cylinder on the device to be stopped in mid stroke.
  10. Never hold an animal in a head restraint device for more than a few seconds. The animal should be stunned or ritually slaughtered immediately after the head holder is applied. Head restraint is much more aversive than body restraint. Animals can be held in a comfortable body restraint for longer periods. The animal's reaction should be observed. If the animal struggles or vocalizes this is an indication that the device is causing discomfort.
  11. Restraint devices should not have sharp edges that dig into an animal. Parts that contact the animal should have smooth rounded surfaces and be designed so that uncomfortable pressure points are avoided.

In conclusion of this animal restraint section, in most plants it is possible to modify existing restraint devices to lower vocalization and agitation scores. Balking at the entrance is also easy to reduce. Most of the modifications that would reduce animal agitation and vocalizations can be installed at a minimum expense. The estimated cost to modify a system is usually between $200 to $2000. Some of the most common and simplest modifications which will reduce balking, agitation and vocalization are:

  1. Install mufflers to stop air hissing.
  2. Install flow controls on hydraulic or pneumatic equipment to provide smooth, steady motion of parts that press against the animal.
  3. Install lockable pressure regulators to control maximum pressures.
  4. Extend the solid hold down cover on conveyor restrainers to induce cattle to ride quietly.
  5. To reduce balking at the entrance of a conveyor restrainer install a light to light up the restrainer conveyor entrance. This light should be above the lead up chute. Block light coming up underneath the restrainer conveyor with metal shields.
  6. To prevent slipping, install a metal grid on a stunning box floor and install non-slip cleats on a conveyor restrainer entrance to reduce agitation due to slipping.

Pigs and cattle should enter a restraint device easily and be held in the device with a minimum of agitation and vocalization. If animals balk at the entrance to a restraint device the cause of balking and refusal to enter should be determined instead of resorting to increased electric prodding. If animals struggle or fight a restraint device the problem should be identified and corrected instead of using more pressure.

Restraint for Ritual Slaughter

Three plants which conduct kosher slaughter were observed. Subjective ratings of the restraint device ranged from excellent to a serious problem (Table 16).

Table 16: Vocalization and Agitation Scores for Cattle Held in Upright Restraint Devices for Kosher Slaughter

Animal Percent Vocalized Percent Agitated Rating Reason for Vocalization
Plant 1 Beef Cattle 0% 0% Excellent Cattle entered calmly. Skilled operator. No excessive pressure.
Plant 2 Beef Cattle 6% 0% Barely Acceptable Excessive pressure due to wrong type of control valves.
Plant 3 Beef Cattle 12% 2.4% Not Acceptable Careless operator, cattle pinched by moving parts of the apparatus.
Plant 2 Holsteins 35% 0% Serious Problem Restraint apparatus too short for long Holsteins, resulting in excessive pressure.

All three plants had good non-slip floors and no slipping. This helped keep agitation scores low. Two plants had ASPCA boxes and one plant had a conveyor restrainer with a head holder. Line speeds were from 90 to 200 per hour. Vocalizations induced by prods were subtracted.

All three plants had restraint devices that held the cattle in an upright position. Both plants 1 and 2 had a skilled careful operator. The problems in plant 2 which caused vocalization in 6% of beef bred cattle were all mechanical. There was loud air hissing on the box and it had the wrong type of control valves. This caused excessive pressure to be applied because the operator either had to apply full pressure or none at all. This problem can be easily corrected for about $2000 by installing return to center valves which give the operator the ability to control the amount of pressure. The restrainer in plant 2 was originally designed for shorter beef cattle and it was too short for long Holsteins. This caused 35% of the Holsteins to vocalize. Lengthening the box could also be done at minimum expense by moving the rear tailgate track back about 6 inches. In plant 3 the high vocalization rate was caused by a careless operator who pinched the cattle in moving parts of the apparatus. All vocalizations were in direct response to being pinched. When the restrainer was operated correctly the animals remained calm.

None of the plants surveyed shackled and hoisted live cattle prior to ritual slaughter. The author has observed this cruel practice in several different non-surveyed plants. The author estimates that the vocalization and agitation rates for shackled and hoisted cattle are much higher than the vocalization percentages in the surveyed plants. Dunn, (1990) reported that inverting cattle in a pen which turned the animals upside down resulted in much higher cortisol levels than upright restraint.

Ritual Slaughter Cutting Method

The quality of the ritual slaughter method was tabulated in two plants. Only one miscut was observed out of 362 cattle. When animal welfare during ritual slaughter is being assessed one must separate the variable of restraint from the variable of the actual throat cutting without stunning (Grandin 1994a, Grandin and Regenstien 1994). The author has observed that when cattle are held in a restraint device which holds them in a comfortable upright position a properly done kosher cut causes almost no reaction (Grandin 1994, Grandin and Regenstien 1994).

The vocalization and agitation scores in Table 16 were all due to problems with the restraint device which can be easily corrected. For further information on ritual slaughter see Grandin and Regenstien (1994), Grandin 1994a). Good animal welfare can be maintained during ritual slaughter provided the animal is held quietly in a device that holds it in a comfortable upright position.

Power Gate Operation

Table 17: Operation of Powered Gates in 20 Plants

Rating Number of Plants Percentage of Surveyed Plants Comments
Number of plants that do not have powered gates. 8 40% All gates manually operated.
Excellent (Gates equipped with pressure limiting device) and carefully operated. 7 35% Animals could either stop downward movement of a vertical slide gate or the gate was equipped with a sliding bottom panel, or flexible rubber flap which formed the lower third of the gate.
Acceptable (Careful operation of gates.) 4 20% Vertical slide gates may have had enough power to push an animal to the floor, but they were carefully used, and pushing animals down was not observed.
Serious Problem (gate caused animal to fall down.) 1 5% Vertical slide gates on the stunning box knocked one animal to the floor. Box operator was skilled and careful, but he was overworked.

Table 17 shows the operation of powered gates in 20 different plants. Seventy-five percent of the plants had either no power gates or power gates equipped with pressure limiting devices which made it possible for an animal to stop movement of a gate. In one plant an animal was knocked to the floor by a power gate. The stun box operator in this plant was overworked. This was rated a serious problem.

One of the best pressure limiting devices was construction of the lower third of a vertical slide gate from a rubber flap. Both pigs and cattle think it is solid so they don't try to push through the flap. The flexible rubber flap also eliminates costly bruises. When powered gates were being evaluated from a welfare standpoint a gate that knocked an animal to the floor or caused it to fall down was rated a serious problem.

Facility Maintenance and Bruise Points

Seventy-eight percent of the surveyed plants had yards and chutes which were rated either excellent or acceptable for prevalence of bruise points and general maintenance (Table 18).

Table 18: Maintenance and Prevelance of Bruise Points in the Stunning Chute Area, Yards and Unloading Chutes in 18 Plants

Ratings Number of Plants Percentage of Surveyed Plants Comments
Excellent 9 50% Had either new facilitites or well maintained older facilities
Acceptable 5 28% A few sharp edges on gate latches.
Not Acceptable 2 11% One plant had a broken gate in the main drive alley. Two plants old, poorly maintained yards.
Serious Problem 2 11% Yards in a state of disrepair and sharp edge on bottom of stunning box door in one plant.

The design of the facility layout was not rated. The ratings were based on the physical condition of the pens, ramps and chutes. Two plants (11%) of the 18 plants surveyed were rated as having a serious problem because large portions of the yard were in general disrepair with many sharp edges and broken fences or gates. One plant had a sharp edge on the bottom of the stunning box door.

Pen Stocking Density and Water Availability

Seventeen plants were rated for overcrowding of the holding pens in the yards. Eighty-two percent were rated as excellent (Table 19) and none was rated as a serious problem. Only one plant had pens overcrowded with too many pigs.

Table 19: Pen Stocking Density in the Yards in 17 Plants

Ratings Number of Plants Percentage of Surveyed Plants Comments
Excellent 14 82% All pigs had enough room to lie down.
Acceptable 2 12% Cattle slightly over crowded.
Not Acceptable 1 6% Pigs did not have sufficient room to lay down. Held for a short period of time.
Serious Problem 0 0%

As stated previously there were many more welfare problems in the stunning chute areas compared to the holding pens. None of the plants used electric prods in the yards. The most common tools used for moving pigs were either canvas slappers or plastic paddles. In the best plants the slapper was used to make a noise by hitting the fence or a person's boot. Lean hybrid pigs move more easily and became less agitated when workers avoided hitting the animals with the slapper. All plants except one had adequate availability of water (Table 20).

Table 20: Availability of Drinking Water in 18 Plants

Ratings Number of Plants Percentage of Surveyed Plants Comments
Excellent 14 77% All pork plants had adequate watering facilities.
Acceptable 3 17% Three cattle plants had a few pens without water.
Not Acceptable 0 0%
Serious Problem 1 5% No Water.

Evaluation of Vehicles and Unloading Procedures

A total of 57 vehicles were observed and rated at 14 different plants (Tables 21 and 22). The following criteria were used to assign ratings:

Excellent -Animals walk off quietly and the vehicle is well maintained and loaded at the correct stocking density.

Acceptable - Most animals walk off quietly and loaded at the correct stocking density.

Not Acceptable - Obviously overloaded and prodding animals excessively.

Serious Problem - Obvious rough handling, which made many animals fall, and/or serious overloading.

To insure objectivity and a degree of randomness trucks were rated in the order of arrival until a maximum of five trucks per plant were rated. In smaller plants it was often not possible to rate five trucks. In large plants the author rated the first five trucks which arrived when the author walked out to the unloading area. The truck drivers were not aware of the survey and ratings probably reflect their true behavior (Tables 21-22).

Table 21: Evaluation of Vehicles and Unloading Procedures of 32 Randomly Chosen Vehicles at 8 Different Pork Plants

Vehicle Type Number of Each Type Percentage of Each Type Number & Percentage Excellent Acceptable Not Acceptable Serious Problem
Double deck cattle semi with possum belly 16 50% 7 (43%) 3 (19%) 3 (19%) 3 (19%)
Straight semi trailer for pigs 8 25% 6 (75%) 1 (12%) 0 (0%) 1 (12%)
Gooseneck stock trailers 5 15% 3 (60%) 1 (20%) 0 (0%) 1 (20%)
Farm Trucks 2 6% 0 (0%) 1 (50%) 0 (0%) 1 (50%)
Triple Decker Semis 1 3% 1 (100%) 0 (0%) 0 (0%) 0 (0%)
TOTALS 32 Vehicles
17 (53%) 6 (19%) 3 (3%) 6 (19%)


Excellent - Animals walk off vehicle quietly. The vehicle is well maintained and loaded properly.
Acceptable -Most animals walk off quietly.
Not Acceptable - Overloaded or excessive prodding.
Serious Problem -Rough handling, seriously overloaded or excessive prodding that makes animals fall.

Table 22: Evaluation of Vehicles and Unloading Procedures of 25 Randomly Chosen Vehicles at 6 Different Beef Plants (3 Fed Beef, 3 Cows)

Vehicle Type Number of Each Type Percentage of Each Type Number & Percentage Excellent Acceptable Not Acceptable Serious Problem
Semi trailer full width, rear door 5 20% 5 (100%) 0 (0%) 0 (0%) 0 (0%)
Semi trailer narrow, rear door 16 64% 13 (81%) 2 (12%) 0 (0%) 1 (6%)
Semi trailer, side load 1 4% 0 (0%) 1 (100%) 0 (0%) 0 (0%)
Gooseneck Stock Trailer 1 4% 1 (100%) 0 (0%) 0 (0%) 0 (0%)
Farm Truck 1 4% 1 (100%) 0 (0%) 0 (0%) 0 (0%)
Lowboy Pickup 1 4% 1 (100%) 0 (0%) 0 (0%) 0 (0%)
TOTALS 25 Vehicles
21 (84%) 3 (12%) 0 (0%) 1 (4%)


Excellent - Animals walk off vehicles quietly and no prods are used.
Acceptable - Most animals walk off quietly.
Not Acceptable - Overloaded or excessive prodding.
Serious Problem - Rough handling, excessive prodding or animals falling down.

Overall the condition of the vehicles was mostly excellent or acceptable. There were only two vehicles that had inadequate internal ramps which caused animals to fall. Over ninety percent of the vehicles were well maintained and many were new. There were only two old and poorly maintained vehicles. Both of these were farmer owned. The most popular vehicle for both pigs and cattle was the double deck cattle semi with a possum belly. Out of 57 vehicles there were only two that were not acceptable from a welfare standpoint due to slick internal ramps. More problems were observed unloading pigs compared to cattle. Cattle will often unload by themselves with little aid from the driver. Out of 25 cattle trucks all but one driver was rated either excellent or acceptable. One cattle truck (4%) was rated a serious problem due to excessive prod usage. The driver allowed his boy to poke almost every animal with an electric prod.

Out of 32 vehicles transporting pigs 23 (72%) had drivers who were rated either excellent or acceptable. Six (19%) vehicles were rated as having a serious problem due to overloading, slick ramps (2 vehicles), excessive electric prodding (3 vehicles), or dirty truck (1 vehicle). The one dirty vehicle had previously been used to transport cattle. Pigs were loaded in it, and it contained two to three inches of liquid cow manure. The yard personnel at the plant informed the author that this particular independent driver was really bad and that during the winter he brought in a load of pigs with some of the pigs frozen to the floor in cow manure.

The vast majority of the drivers were professional and acted as professionals. Independent truckers and farmers were more variable in their behavior compared to drivers who drove company owned trucks for either the packing plant or for a large feedlot or farm. The independent truckers and the farmers had a tendency to be either really excellent or really bad. There were approximately two or three excellent or acceptable independent truckers and farmer drivers for every one that was rated either not acceptable or a serious problem.

Overall the vast majority of drivers did a good job. Only 7 (12%) out of 57 were rated a serious problem. There were more problems on pig trucks compared to cattle trucks. Only one cattle truck driver was rated a serious problem due to over prodding. The author has observed that the livestock handling skills of truck drivers have improved over the last ten years. Most of the improvement is due to an expansion of the segment that is really excellent. However the percentage of really bad truck drivers h as remained at around 10% for many years.

Handling of Non-Ambulatory Animals

Methods for handling animals which were unable to walk were observed in eight plants (Table 23).

Table 23: Observations of Handling of Non-Ambulatory Animals in 8 Plants

Number Observed Animal Type Reason for Being Non-ambulatory Handling Method Rating of Handling
Plant 1 1 Holstein Dairy Cow Unknown Shot on truck with a captive bolt stunner and stunned animal dragged out. Excellent
Plant 2 1 Cow Unknown Shot where it lay in the yard and then moved. Excellent
Plant 3 1 Boar Stress Syndrome Tractor with a special, large bucket. Excellent
Plant 4 4 Market Pigs Stress Syndrome Bobcat with regular bucket. Acceptable
Plant 5 1 Market Pig Stress Syndrome Bobcat with regular bucket. Acceptable
Plant 6 25 Holstein Dairy Cows Variety of Causes (See Table 23) Moved on large metal plates in a plant which handels non-ambulatory cattle from local dairies. Acceptable
Plant 7 1 Market Pig Stress Syndrome Drag onto cart with winch. Not Acceptable
Plant 8 1 Beef Cow Unknown Picked up and moved by shoving bare, forklift forks under it. Serious Problem

Six out of eight plants had either excellent or acceptable handling of downed animals. In pork plants a skid steer loader (Bobcat) was the most popular method for moving non-ambulatory pigs. Pigs can be handled in an acceptable manner with a skid steer loader if two people perform the procedure. One person drives the machine and the other rolls the pig into the bucket. Shoving a pig up against a wall with the bucket to get it into the bucket should be forbidden. One plant received a serious problem rating for moving non-ambulatory cows with bare fork lift forks. In the best beef pant a downed cow which arrived on a truck was shot with a captive bolt on the truck prior to being dragged off. Removing a downed non-ambulatory cow from the center compartment of a possum belly cattle truck in a humane manner is almost impossible. The most humane method is to shoot non-ambulatory cattle with a captive bolt stunner before they are removed from the truck. In Canada non-ambulatory animals are inspected in the truck and stunned in the truck. Unfortunately at the present time the USDA requires that the animals be removed from the vehicle for antemortem inspection, but in a few plants where the veterinarian in charge really cares about animal's welfare, this directive is ignored. At two of the surveyed plants the plant manager complained that they used to shoot non-ambulatory animals on the vehicle until the veterinarian in charge forced them to drag the animals off. The author strongly recommends that the USDA allow non-ambulatory animals to be shot with a captive bolt gun before being removed from the vehicles. Arriving non-ambulatory animals can be inspected on a vehicle without endangering the inspector's safety. Safety was one reason why the inspectors are not allowed on the vehicle to do ante-mortem inspection on downed animals. Below are some recommendations for safe ante-mortem inspection of a non-ambulatory animal on a vehicle. Some types of animals are more dangerous than others. Market weight pigs present a minimal safety hazard whereas cattle can be dangerous. It is essential to unload all the normal cattle from the compartment before the inspector enters. Cattle may remain in other compartments which are separated with gates. Wilder beef cattle and all bulls are much more dangerous than tame dairy cows. It is usually safe to examine a downed dairy cow on a vehicle but a wild beef animal which is more fearful of people is more likely to suddenly get up and run over a person. Bulls must always be treated with caution because they can be dangerously aggressive. This includes both dairy and beef bulls. Boars and some sows may also be dangerous. To protect the safety of USDA personnel and to improve animal welfare the author recommends:

Non-Ambulatory Plant

One of the surveyed plants was a small operation which specialized in processing non-ambulatory dairy cows from local dairies. Most cows traveled less than an hour to the plant. Since the downed cows traveled only a short distance they were in better body condition than non-ambulatory and poor condition cows that the author observed in other surveyed plants. Table 24 summarizes the condition of 25 non-ambulatory cows which were observed in this plant.

Table 24: Condition of 25 Non-Ambulatory Dairy Cows Brought to a Small Plant That Processes Downed Cattle From Local Dairies

Condition of Animal Number Percentage Number of Fresh Leg Cuts: Likely to have been dragged Comments
Calving Problems 4 16% 2 2 DOAs due to internal bleeding.
Dehydrated; Very thirsty when offered water. 5 20% 0 Had obviously not been watered at the dairy.
Emmaciated 1 4% 0
Hoof Trimming Restraint device injuries, old healed chain marks on legs. 3 12% 0
Swollen lower foot infected. 3 12% 0 Open, red infected lesions. Stunner operator blamed careless hoof trimming.
Splitter 4 16% 0
Unknown 5 20% 0

A total of 16 cows (64%) were alert and could be positioned in a sternal recumbency position. Overall, these non-ambulatory cows were in better condition than downers which have traveled long distances.

Twenty-four percent (six cows) of the cows had either obvious injuries inflicted by careless hoof trimming or suspected hoof trimming injuries. Only one animal (4%) was emaciated and 16 cows (64%) were very alert and the plant employee positioned them in sternal recumbency. One of the author's major concerns is that there appeared to be some cases where the dairy was neglectful and welfare was severely compromised.

Five cows (20%) arrived extremely thirsty. When plant employees filled a bucket of water they were so thirsty that they were trying to drink before the bucket was filled. One cow drank three five gallon buckets of water. The plant employees informed the author that most dairies do a good job but they received cows from one or two really bad dairies. These dairies had a reputation for bringing in cows in very bad condition and drug residue. The worst problems were concentrated in a few bad dairy operations.

The non-ambulatory cows were brought to the plant in small van type trucks equipped with a slide plate. The author rated the unloading method acceptable. The slide plate with the cow on it was slid down a ramp. The plant employees and the truck drivers all tried to do a good job. Four different trucks were observed and several made more than one trip. Plant employee behavior and truck driver behavior would all be rated excellent.

No electric prods were used by anybody and there were no electric prods on the plant premises. Cows were never dragged at the plant, but cows probably had to be dragged to get them onto the trucks. The trucks could very easily be modified by installing hydraulic powered tailgate lifts onto the trucks. These lifts are commercially available for use on delivery trucks. This is an off the shelf item that is easy to install. These lifts would make it easy to load the trucks and dragging could be totally eliminated.

Condition of Cattle

Table 25 outlines the condition of cattle in the other surveyed plants, excluding the specialized non-ambulatory cow plant. The incidence of cattle with severe problems was extremely low. The author walked once through the yards of each plant and observed approximately 2500 cows and bulls and 3000 fed steers and heifers. There were no cows with severe necrotic ocular neoplasia and only 18 head in four different plants of emaciated cattle. The four cow plants surveyed did not buy the really poor cows or bulls. The author estimates that approximately half of the cows and bulls at the surveyed plants were beef breeds and the other half were dairy cattle. Dairy cows were estimated to have slightly more problems than beef cows. However the author is very concerned about the cattle that she heard about.

Table 25: Prevelance of Deads and Stressors in the Stunning Chute Area in 4 Pork Plants With Either High or Low Use of Electric Prods

Plant1 Electric Prod Practices in Stunning Chute Stressors Number Per2 100 of Observed Pigs Stun Chute Deads Number Per 1000 of Observed Pigs
1 Low Battery operated prod. 15% of pigs prodded in stunning chute. 2 1 per 1000 0 0
2 Low Weak electric prod 5% of pigs prodded in stunning chute. 0 0 0 0
3 Low Broken electric prod which had almost no effect on the pigs. Excellent handling. No prod score. 1 0.75 per 1000 0 0
4 High Homemade, very strong electrical prod which made most pigs squeal. 48% of pigs prodded in the stunning chute. Rough handling-worst pork plant in the survey. 8 4 per 1000 4 2 per 1000
1 All plants were large pork plants with a minimum line speed of greater than 700 pigs per hour. In all four plants handlers kept up with the processing line. Weather conditions were ideal for handling pigs. No very hot or very cold weather.

2 Number per 1000 adjusts numbers for line speed.

A truck driver interviewed at one of the surveyed plants reported that he regularly transports loads of half dead cows either to Mexico or to one of the four Federally inspected plants which will still accept cows in very poor condition. He said he often has 1 or 2 downers and a dead cow per load. The cows with severe necrotic ocular neoplasia were usually transported to Mexico. The incidence of cows in extremely poor condition was much lower in the surveyed plants compared to the 1994 Non Fed Beef Audit which was conducted by Colorado State University for the National Cattleman's Beef Association (Smith et al 1994). The difference between the two surveys is most likely due to two factors. Firstly, none of the plants which are known to slaughter really poor cattle were surveyed, and secondly, the cattle industry took steps after the 1994 Non-fed Beef Audit to reduce the incidence of downed and very poorly conditioned cattle.

The author estimated that ninety-nine percent of all the cows and bulls observed in the plant yards and moving through the chutes were in good condition and free of obvious problems such as emaciation. The leg problems observed at the non-ambulatory cow plant were not observed in the other cow plants. One careless hoof trimmer was the cause of many downers at the non-ambulatory plant. The incidence of severe lameness in all the other cow and bull plants was almost non existent and only 4 deads were observed. No severe lameness was observed at the plants processing fed steers and heifers. However at one plant cattle from one feedlot had elongated hooves due to founder. The cattle were observed in the stunning chute area. The animals were able to walk normally in the stunning chute area but the plant manager complained that cattle sometimes fell down during truck unloading. No cattle fell during unloading during the survey, but possibly foundered hooves could cause falling during unloading. No fed cattle with foundered hooves were observed during truck unloading.

Condition of Sows

The condition of sows was much worse than the condition of cows and bulls. Sows were observed in two surveyed plants. One of the plants buys only the best sows and the other bought some of the poorer sows. Many problems were observed in sows. Approximately 16% of the sows which were unloaded from five randomly chosen trucks at the plant which purchased the poorer sows were obviously lame (Table 26). Lameness was scored during unloading.

Table 26: Condition of Sows

Percent Lame Number observed Comments
Truck 1
Plant 1
50% estimate 30 estimate 2 sows severe pressure sores
Truck 2
Plant 1
28% (12hd) 42 2 DOA's, filthy truck
Truck 3
Plant 1
13% (6hd) 63 2 severely lame sows
Truck 4
Plant 1
11% (4hd) 37 1 sow had football sized growth on her leg
Truck 5
Plant 1
8% (9hd) 109 Lean white hybrids showing lots of stress symptoms. 1/2 of lame animals were severe, was foundered
Plant 2 ? ? Observed several hundred sows in the pens lying down. Appeared to be better sows than in plant 1. Could not observe for lameness.

All sows in Plant 1 were observed during unloading. No trucks were overloaded. Both reports from plant personnel and observation indicated that there was a tendency for lean hybrids to have more lameness.

An interview with the plant manager indicated that the condition of sows was becoming worse. His opinion was that the new lean hybrid sows were weaker and that some of the new large farms did not properly prepare sows for market. He reported that on some of the large farms the sows are sent to slaughter while they are still wet with milk. This results in the plant having to put the belly meat in rendering. He also stated that the sows arrived at his plant in much poorer condition. The plant manager expressed disgust with the deteriorating condition of sows and that he is concerned about animal welfare.

Condition of Market Pigs

Several plant managers interviewed stated that the incidence of DOA's (dead on arrival) and stress deads in the yards was double in the new lean hybrids. Grandin (1994b) has reported similar findings. The weather conditions during the survey were mild and no surveyed pork plants were visited during extremely hot humid weather. Table 23 shows that the major cause of non-ambulatory market weight pigs is porcine stress syndrome. The percentage of lame pigs was almost none. Death losses were very low due to mild weather and good to excellent handling in most of the surveyed plants. Table 27 shows how quiet handling and minimal use of electric prods can greatly reduce the prevalence of dead or non-ambulatory stressed pigs. Three pork plants with minimal prod use and one plant with rough handling and excessive prod use were compared.

Table 27: Conditions in Cattle That May Interfere With Walking and Handling1

Animal Type Number of Plants Conditions Observed
Fed Cattle 5 Fed cattle seldom have leg problems that interfere with walking. Observations of several thousand cattle indicated that all the cattle could walk easily with the exception of 100 head from one feed lot which had elongated, foundered feet. Theses animals were not lame but could be more prone to slipping and falling. No DOAs.
Cows and Bulls 6 Cows and Bulls6Emaciated - 18 head in four plants.
Extreme Pendulous Udders - 3 head
Ram's Horn Feet - 1 head
Dead - 4 head
Severe Necrotic Ocular Neoplasia - 0 head
Estimate that over 99% of cows and bulls were in good condition.
Formula Veal
All walked normally. A few calves showed slight signs of selenium deficiency.
1 All cattle in the yards were observed while walking through the yard once. Cattle moving through the stunning chute were also observed. Estimate that over 2500 cows and bulls and 3000 fed steers and heifers were observed.

The rough plant had at least three times as many deads and stressors in the stunning chute area. Several plant managers and livestock procurement managers complained during the survey that the new lean hybrids are much more difficult to handle than the other pigs. The author has written numerous articles about handling problems with highly excitable lean pigs which have a greater tendency to balk and pile up (Grandin 1993, 1994b, 1996). Producers can produce pigs that are easier to drive at the plant if they train the animals by walking through the pens in the finishing house for 10 to 15 seconds per pen per day. This trains the animals to get up quietly and flow around the person. Pigs from a highly excitable genetic line can be almost impossible to handle quietly in a 1000 pig per hour line unless the producer has walked the pens (Grandin 1994b). This can create a serious welfare problem.


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The effectiveness of high frequency electrical stunning in pigs
Meat Science 31: 481-491

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Quality control of stunning
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Stunning and slaughter of sheep and calves in New Zealand
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Meat Industry Research Conference, MIRINZ, Hamilton, New Zealand

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Restraint of livestock
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Euthanasia and slaughter of livestock
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Behavior of slaughter plant and auction employees towards animals
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Stress in cattle after handling, transport, and slaughter
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Humaneness of electro-immobilization unit for cattle
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Aversion of sheep to electro-immobilization and physical restraint
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Livestock Bruising Project: Stockyard and Crate Design
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