Presented at American Meat Institute
2000 Conference on Animal Handling and Stunning
February 8-9, 2000
Westin Crown Center, Kansas City MO

1999 Audits of Stunning and Handling in Federally Inspected Beef and Pork Plants

By Temple Grandin
Dept. of Animal Sciences
Colorado State University
Fort Collins, CO 80523-1171


Stunning of beef cattle has greatly improved since the USDA survey done by the author in 1996. In 1996 only 30% of the plants were able to stun 95% or more of the cattle with one shot. In 1999, 90% of the plants were able to do this. Stunning was scored in 41 Federally inspected beef plants in 11 different states. The percentage of cattle that vocalize (moo or bellow) during handling has also greatly improved. Vocalization (mooing, bellowing or squealing) is an indicator of animal stress and discomfort. In many plants electric prods had been replaced with other driving aids such as flags or plastic bags. One remaining problem area in attempting to stun 390 cattle per hour with one operator.

A total of 19 Federally inspected pork plants were audited in 8 different states. Seventeen out of 19 plants (89%) induced instant insensibility in 100% of the pigs. Pig handling has greatly improved and this was reflected by less squealing. This fact made it possible to develop a new scoring system for objective scoring of the amount of squealing. This was not possible in 1996 because pigs squealed continuously in most plants. Eleven plants were evaluated with the new system and eight out of 11 plants (72%) had either acceptable or excellent scores. Compared to 1996 there is one major problem area. In some plants, there were greater numbers of heavy weight pigs from excitable genetic lines which had a higher incidence of "stressor" pigs which became non-ambulatory. Some producers are starting to correct this problem. This problem must be corrected through selective breeding. Overall throughout the meat industry handling and stunning has greatly improved compared to survey data collected in 1996.


Handling and stunning of animals has improved. The results of the 1999 audits of 61 plants show great results improvement compared to data collected in 1996 (Grandin 1998a,1997a). Audits of animal handling and stunning are now routinely being conducted by both plant management and major customers. Improving animal handling and stunning practices provides the benefits of both better animal welfare and meat quality.

Good handling also has economic benefits. Practical experience in many pork plants has shown that reducing electric prod use and quiet handling in the stunning chute reduces PSE about 10%. PSE is a serious quality defect. Quiet careful handling of cattle will significantly reduce bruising (Grandin, 1981). Other benefits of the improved cattle handling are safer working conditions and prevention of loss of production caused by agitated cattle.

The 1996 survey done for the USDA (Grandin, 1997a, 1998a) was used as the basis for developing objective scoring guidelines for the American Meat Institute (Grandin, 1997b). The data contained in these 1999 audits has verified that the American Meat Institute scoring system is practical and can be easily implemented in the field to assess animal handling and stunning in beef plants. However, the pork scoring system has have been more difficult to implement. Data collected during the 1999 audits has now been used to develop a more practical way to score pig handling.

The 1999 audits of animal handling cover more than half of the medium sized and large beef and pork plants in the U.S. This sample is very representative of U.S. beef and pork plants. The McDonald's Corporation has been a leader in improving both food safety and animal welfare. I have been working with them to develop auditing procedures and to train their HACCP food safety team. One goal of the 1999 audits is to identify "Best Practices" which can be used throughout the industry. Many plants had greatly reduced electric prod use and replaced many of the electric prods with other driving aids such as flags, plastic bags and plastic paddle sticks. Large 30 in x 30 in flags made from plasticized tarp cloth were a major innovation for moving pigs. Other "Best Practices" were ergonomic handles on pneumatic stunners and the use of spot lights to improve animal movement into restrainers. In several plants a rack was built to hold cartridge fired stunners. This rack facilitated rotation of the stunners to prevent them from getting overheated. Overheated stunners are less effective. For both pigs and cattle, filling the crowd pen and staging areas half full greatly improves handling. The good news is that these changes did not require expensive plant renovations to enable a plant to obtain an acceptable score for animal handling and stunning. In beef, only 2 plants (5%) had to make major renovations to their handling systems. In pork plants, no major renovations were needed.


A total of 42 Federally inspected beef plants and 19 Federally inspected pork plants were audited during 1999 in sixteen different states. All audits were announced in both the 1996 survey and the 1999 audits. In beef plants,a minimum of 50 cattle were scored in plants with line speeds under 100 cattle per hour and 100 or more cattle were scored in plants with higher line scores. If more than 100 animals were scored, additional animals were scored in groups of 100. A complete description of the scoring methods are in the 1996 USDA Survey and the American Meat Institute Guidelines (Grandin, 1997a,b). In all beef plants stunning efficacy, insensibility and vocalization (moos or bellows) were scored and in all pork plants, stunning and insensibility was scored. The auditor walked through the yards and chute areas and other welfare problems were noted.

New methods were developed for evaluating squealing in pigs as a measure of the quality of handling. They will be described later in this paper. In some beef and pork plants, electric prod use was scored. Vocalization was used as the primary method for evaluating handling because it is easier to score and it is a sensitive indicator of animal stress and discomfort (Grandin, 1998b; Dunn, 1990; Warris et al., 1994; White et al., 1995; Watts and Stookey, 1998; Weary, 1998). All scoring methods have been designed to be simple to use in the field. Stunning, vocalization and insensibility are scored on a yes/no basis to help remove subjectivity. For example, a steer either vocalizes (moos or bellows) or he does not. The vocalization score is the percentage of cattle that vocalize during stunning and handling in the chutes. Vocalization of cattle standing undisturbed in the yards is not scored.

The audits were done by either the author or a member of the McDonald's HACCP team which had been trained by the author. The author collected data in approximately half of the plants. On the tables, plant numbers cannot be compared between tables. They are scrambled for confidentiality reasons. Line speeds were rounded off to the nearest interval of 10 to insure confidentiality.

Results and Discussion

Captive Bolt Stunning of Cattle

Compared to the USDA survey done in 1996 (Grandin 1997a, 1998a) stunning efficacy percentages have greatly improved. In 1996 only 30% (three out of ten beef plants) were able to stun 95% or more of the cattle with a single shot. The 1999 data shows that 90% of the plants were able to stun 95% or more of the cattle with a single shot (Table 1). Thirty-seven percent of the plants were able to stun 99% to 100% of the cattle correctly on the first attempt. Cattle which were not rendered insensible with the first shot were immediately restunned. Table 2 shows the comparison between fed beef and cow plants. Overall stunner maintenance has improved, with the exception of one plant which had a malfunctioning pneumatic stunner due to water in the air supply. Compared to 1996 data, a lack of maintenance is no longer the primary cause of poor stunning. The major causes of stunning scores below 95% were cattle slipping in the stun box, one operator attempting to stun 380-390 cattle per hour or a clogged trigger mechanism on a pneumatic stunner. A clogged trigger mechanism on a pneumatic stunner can be prevented by washing it frequently with water.

One of the biggest concerns is attempting to stun 380-390 cattle per hour with one person. All plants operating at 380-390 per hour with two people using cartridge-fired stunners were able to stun 95% or more of the cattle with a single shot. Plants with line speeds of 333 or less per hour were able to achieve the 95% or better level with one operator when they used a pneumatic stunner equipped with an ergonomic handle. This handle prevented twisting strain on the operator's wrists. The pneumatic stunner was suspended on the balancer at a 30-degree angle to facilitate stunning in a conveyor restrainer. The handle was mounted on the back of the stunner housing and it enabled the operator to position the stunner by using a sideways swinging motion. This sideways motion replaced a wrist twisting motion.

One plant had a pneumatic stunner with a worn cylinder bore which no longer provided sufficient compression. When an animal was shot correctly it was not always rendered completely insensible. Even though the stunner was well maintained, the cylinder was too worn to provide sufficient hitting force to render an animal instantly insensible. There is a point where a pneumatic stunner must be discarded. The plant was not tabulated in the audit data because the author was called to help them fix problems prior to the audit. Shortly after my visit they purchased a new pneumatic stunner. A few months later they were audited and they were able to render 100% of the cattle insensible before hoisting to the bleed rail.

The makers of cartridge fired stunners have developed a test stand to determine hitting force. There is a need for a similar test stand for pneumatic stunners. Hitting force measurements obtained on a test stand could be used to determine when a pneumatic stunner should be replaced.

Insensibility in Captive Bolt Stunned Beef Cattle

Forty plants out of 41(97%) of the audited plants were able to render 100% of the cattle completely insensible with a captive bolt prior to hoisting to the bleed rail. All cattle were rendered insensible prior to skinning or removal of feet. One plant failed to achieve 100% insensibility prior to hoisting because they attempted to stun 380-390 cattle per hour with one operator using a pneumatic stunner. When this plant switched to two operators using cartridge fired stunners they achieved a first shot efficacy percentage of 98% and 100% insensibility. In the one plant that had the pre-audit stunner problems. All cattle were reshot and rendered insensible prior to skinning or leg removal.

Vocalization Scores During Handling of Cattle

The average percentage of cattle that vocalized (moo or bellowed) during handling and stunning was 2.74%. The percentage scores are shown on Table 3. This is an improvement compared to the 1998 USDA survey (Grandin 1997a, 1998b). In 1996 only 3 out of 7 beef plants (43%) had acceptable vocalization scores of 3% or less. In 1999, thirty plants out of 42 (71%) had a passing score of 3% or less. Six plants out of 42 plants (14%) had zero percentage of cattle vocalizing and two plants had a serious problem with 17% and 12% of the cattle vocalizing due to excessive use of electric prods. The excessive prod use was due to balking at the entrance of a conveyer restrainer. Simple modifications such as adding a light to illuminate the restrainer entrance and installing a false floor to prevent cattle from seeing a 7-foot drop under the restrainer will usually solve the problem. The type of equipment a plant had or line speed had little or no effect on the percentage of cattle that vocalized. There were 19 plants that had an excellent vocalization percentage of 0 to 1%. Half of these plants had stunning boxes and the rest had conveyor restrainers. Plant line speed also had little effect on the percentage of plants that could achieve a 1% or less vocalization percentage (Table 3). The 10 plants with conveyor restrainers had line speeds ranging from 150 to 390 per hour. The 10 plants with stunning boxes had speeds which ranged from 2 per hour to 250 cattle per hour. Therefore, high line speed appears to have little effect on the incidence of vocalization. In one 1,000 cattle test at 390/hr only 1.3% of the cattle vocalized.

The data was then tabulated to determine if there was a difference between cow plants and fed beef plants (Table 4). Eighty-five percent of the fed beef plants and 57% of the cow plants had vocalization percentages of 3% or less. Table 5 shows the causes of elevated vocalization percentages of greater than 3% of the animals in 12 cow and fed beef plants. In six plants (14%) of the total sample excessive electric prod use due to balking was the major cause of elevated vocalization percentages. Two plants had 17% and 12% vocalization percentages that were caused by excessive electric prod use due to balking.

In two plants cattle balked at seeing movement or cattle feet under the stun box door. In two other plants cattle balked at seeing a steep drop off under a conveyor restrainer. This is easily fixed by installing a false floor (Grandin 1996, 1997a). In an Australian plant which was not tabulated with U.S. data, a 9% vocalization percentage was reduced to 0% by installing a false floor below the restrainer to reduce balking. Lack of proper lighting at the restrainer entrance, airhissing, flapping plastic strips or seeing movement up ahead caused balking in two other plants.

During one test an 8% vocalization percentage due to balking and electric prod use was reduced to 0% by installing a light at the restrainer entrance. For more information on eliminating distractions that cause balking refer to the reference list. Sharp edges on worn and broken restraint equipment caused vocalizations in two plants. In one plant (2%) an excessively charged electric prod caused 7% of the cattle to vocalize. Reducing prod voltage reduced vocalization to 2%. Animals should never be left alone waiting in a stun box or alley. In three small plants with line speeds under 50 per hour isolated lone animals left alone in the stun box or alley were the cause of vocalization percentages of 4%, 6% and 4%.

Electric Prod Use Percentages in Beef Plants

Electric prod use percentages were not formally scored in many plants because vocalization percentages are a sensitive indicator of cattle distress. Vocalization is easier to score than electric prod use. Each animal is scored as either a vocalizer (moo or bellow) or a non-vocalizer on a yes/no basis. It is often very difficult to determine if an animal is actually shocked when it is touched by an electric prod. Another problem is that electric prod strength varies greatly from very weak to strong enough to make most animals vocalize. This makes comparison between plants more difficult, then comparing vocalization percentages. In the best plants a person's primary driving tool was not an electric prod. The employees picked up an electric prod only if an animal refused to move. Employees should not be allowed to carry electric prods around as their primary driving tool. Alternatives to electric prods were used in many plants. Some of the alternative cattle driving tools were rattle paddles, plastic bags, flags and plastic tied to the end of the stick. Plastic waste basket liners made from stiffer plastic that makes a crackling sound worked really well. These non-electric alternatives can be successfully used to move 95% to 100% of the cattle in plants that are free of distractions that cause balking. However, an electric prod is the best tool to use on the few cattle that balk. One little buzz is preferable to abusive hitting or poking of an animal.

In 18 plants it was possible to obtain fairly accurate electric prod use scores because the prod was only picked up when needed to move balking animals or it was used on almost every animal due to constant balking. These plants fell into two distinct groups - plants with balking problems and plants where cattle moved easily with a minimum of electric prod use. Most beef plants have eliminated electric prods in the crowd pen leading to the single file chute and electric prod use was mainly confined to the entrance of the stunning box or restrainer. Eleven plants out of 17 (64%) had electric prod usages of 5% or less of the cattle and four plants (24%) used an electric prod on more than 25% of the cattle. Table 6 shows electric prod use percentages for 17 plants. Data collected on electric prod usage clearly indicates that a beef plant can easily attain an electric prod use percentage of 5% or less.

Electric Stunning of Pigs

Data on electric stunning was tabulated from 19 pork plants (Table 7). Eighty- nine percent of the plants were able to render 100% of the pigs completely insensible prior to hoisting to the bleed rail. Two plants, 11% failed. The causes of the two failures were a poorly designed stunning wand and in another plant the stunner amperage was set too low. The plant had lowered the stunner amperage in an attempt to reduce bloodspotting in the meat. All pigs were rendered insensible prior to scalding. Lean pigs are more prone to bloodspotting and hemorrhages in the meat than fatter pigs. The plant that failed processed lean pigs. In 1996 one out of 10 plants failed to stun pigs properly. One problem area is very large pigs which weigh over 280 lbs. (135 kg). These animals require more time to stun. A plant engineer telephoned the author about problems they had with heavy pigs blinking and starting to regain sensibility. This plant had a 1 100/hr line speed, and it was not included in the 1999 audits because there was simply not enough time to go to all the large plants in 1999.

In the 1999 audits, most plants were scored on both electric stunning wand placement and the percentage of pigs that squealed when the stunning wand was applied. Correct placement of the stunning wand is essential to insure that the electric current passes through the brain, A pig will squeal when the stunner is applied if the wand is energized before it contacts the pig's head. When the wand is applied correctly, the pig will remain silent. Table 7 shows data for 14 plants on the percentage of pigs that squealed when the stunning wand was applied. Squealing during stunning is detrimental to animal welfare because it indicates that the pig felt the shock prior to being rendered insensible. Pigs which remain silent during stunning are instantly rendered insensible and probably feel absolutely nothing. See reference lists in Grandin 1997a, 1994 and Gregory and Grandin 1998.

Measuring squealing was used to assess handling in the pork plants. Squealing is an indicator of pig distress and stress (Warris et al., 1994; White et al., 1995 and Weary et al., 1998). In 1996 squeal scoring was almost impossible because handling was so poor that pigs squealed almost 100% of the time in response to being driven through alleys, chutes and restrainers.

Handling of pigs in many plants has improved since the 1996 USDA survey and it became possible to develop an easy to use squeal scoring system. Many plants have replaced electric prods with other driving tools such as large plastic flags or rattle paddles. Table 9 shows data from 11 pork plants where handling was scored with the new method. The method is very simple and it makes it possible to make rough comparisons between different plants, without the use of specialized equipment. A sound meter works well for measuring squealing within a plant but readings are greatly affected by building materials and machinery noise. A simple decibel meter cannot be used for squeal score comparisons between different plants.

The person scoring squealing during handling stands near the restrainer entrance and enters data as each pig is stunned. One hundred pigs are scored with a yes/no scoring system. As each pig is stunned data is entered for "heard a squeal" or "room quiet." The entire stunning room which consists of the restrainer, chutes (races) and crowd pen is scored. Each stunning cycle serves as a timer for scoring. The system is very objective and simple because no attempt is made to score squeal intensity. The smallest squeal is marked as "squeal." On a CO2 stunning system, data is entered after each gondola is filled. Squealing caused by application of the stunner is not scored because it is scored when stunning is evaluated. Squeals in the restrainer which are not caused by application of the stunner are scored for the handling assessment.

Four plants out of 11(36%) had excellent handling and the room was quiet over 30% of the time (Table 8). Three plants (27%) had poor scores where pigs were squealing 94% to 96% of the time. Excessive electric prod use was the cause of excessive squealing in two plants.

Electric Prod Use in Pigs

Electric prod use was evaluated in 19 pork plants. Electric prod use percentages were not tabulated in all plants due to the difficulty in accurately determining the percentages of pigs prodded. The electric charge in the prods varied greatly between plants from an almost "dead stick" which caused no vocalization to powerful shocks which made most pigs squeal. Four plants (21%) had good handling and electric prods were used on only 5 to 16% of the pigs. There were four other plants (21%) which had definite problems which severely compromised animal welfare. In one plant, electric shockers were permanently mounted on the crowd gate and in the chute. The plant has now removed and thrown out these shocking devices. In the three other plants, workers constantly poked 100% of the pigs with electric prods. At one of these plants 100% prodding was reduced to 38% after employee training. Further reduction was not possible because the pigs balked at reflections off a wet floor. These reflections can be eliminated by moving ceiling monitored lamps. Electric prodding of 21% of the pigs at the restrainer entrance was reduced to 6% after the employee was given a short plastic stick to poke pigs with. The electric prod was then used only on pigs which would not move after one poke with the plastic stick. Table 9 shows data for 8 plants where handlers worked hard to handle pigs correctly and an electric prod was only used when required to keep up with the line. In two plants, distractions such as reflections off water, caused balking which increased electric prod use (Table 9). At one plant a truck driver was observed unloading pigs in an abusive manner. Unloading of trucks was not observed in every plant, but in other plants where it was observed, pigs were handled in a decent manner.

Improved Stunning and Handling Scoring System for Pigs

A new simplified vocalization scoring system was developed for pigs to make pig scoring as easy as cattle scoring. Table 10 shows data for 10 plants where a combined handling and stunning audit score has been determined. This system is designed to score stunning and handling separately but make it possible to combine the two scores to form an overall audit score. In the present American Meat Institute guideline, vocalization in the restrainer is scored, but no differentiation is made between vocalization caused by contacting the pig with an energized stunning wand and vocalization caused by handling problems such as electric prods or a faulty restrainer. The new system also makes it possible to assess handling with a simple vocalization score.

Streamlined Scoring System for Pork Plant Handling and Stunning Audits

A. Scoring Stunning - Two Stunning Scores
  1. Percentage of pigs with correct wand placement so current will pass through the brain.
  2. Percentage of pigs that squeal when wand is applied "hot wands"

B. Scoring Squealing During Handling
  1. Percentage of time pigs are squealing. This is a yes/no scoring system. As each pig is stunned, data is entered for "heard a pig squeal" or "quiet." The entire stunning room including the restrainer, chutes and crowd pen is scored. The auditor should stand near the restrainer entrance. The auditor must not stand in front of the stunner, because he/she will be too far away to score squeals in the crowd pen that leads to the single file chute. On automatic stunning systems here it is not possible to see the wand application from the restrainer entrance score "quiet" or "squeal" as each pig enters the restrainer.

Some plants are installed two restrainers and chute systems so that 1200 pigs per hour can be reduced to 600 per hour. If these two systems are in the same room it is not possible to determine which chute or crowd pen a squeal came from. Score the entire room and convert the score by taking the percentage of time the pigs are quiet and doubling it.

Example -87% of time squeal 13% of time quiet
13 13 = 26% time quiet
Final Score = 74% of the time squealing

For plants with one restrainer and chute system no conversion is needed. Example 87% of time squeal remains 87%

Score a minimum of 100 pigs for stunning and a separate group of 100 pigs for squealing during handling. Two separate groups must be scored to avoid mixing up "hot wands" with squealing caused by electric prods and handling problems. In CO2 systems, squealing caused by electric prods or handling problems must be separated from squealing caused by a pig's reaction to the gas.

Calculation of Scores - A plant automatically FAILS if a pig showing any sign of sensibility is observed on the bleed rail. A separate stunning score and squeal score during handling is tabulated. The two scores are combined to determine an overall stunning and handling audit score. The scoring system is explained below.

Stunning - Subtract one point off for each misplaced wand and for every pig which squeals when the wand is applied, to obtain a combined stunning score. Score a minimum of lOO pigs. If the same pig both squeals and the wand is placed in the wrong position, take 2 points off.

Point System for Stunning - Wand Position and "Hot Wands"
100 to 99 Excellent 0 to 1 point off
98 to 97 Acceptable 3 points off
96 to 95 Not Acceptable 5 points off
Below 95 Serious Problem 10 points off

Squealing during handling - Calculate percentage of stunning cycles that pigs were squealing. The smallest little squeals are recorded.

Point System for Squealing During Handling
70% or less of the time squealing Excellent 0 points off
85% to 71% of the time squealing Acceptable 2 points off
86% to 95% of the time squealing Not Acceptable 5 points off
over 95% of the time squealing Serious Problem 10 points off

If a one number overall audit score is desired, it can be calculated by subtracting points from 100. The points off for the stunning score and squeal score are subtracted. This system is designed to equally weight stunning and handling. The stunning score and the handling score are combined to form an overall audit score for stunning and handling.

Overall Audit Score (Optional)
Excellent 98 to 100
Acceptable 95 to 97
Not Acceptable 94 to 90
Serious Problem Below 90

Fail if observe a pig showing sensibility signs on the bleed rail. All scores are INVALID. Scores below 90 FAIL.

USDA Procedures for Downer Cattle

In two beef plants handling of downer non-ambulatory cattle was a concern. At the first plant, the USDA Veterinarian was instructing plant employees to violate the Humane Slaughter Act. Plant employees were told to drag sensible live downers out of the single file chute to the stunner. This is a direct violation. The regulations state "the dragging of disabled animals and other animals unable to move is prohibited. Stunned animals may, however, be dragged" (Humane Slaughter Act, 1978). He should have instructed employees to shoot the downed animal with a stunner prior to dragging.

In a second beef plant, emaciated, downers had been tagged with USDA "suspect" tags which would allow them onto the slaughter floor. These cattle should have been condemned at ante-mortem inspection, which would have prevented them from being allowed inside the plant? They were emaciated and covered completely with manure. They were no longer able to lie in sternal recumbency or raise their heads. Inspectors in most other plants would have condemned these cattle. There is a need for objective guidelines for ante-mortem condemnation for USDA field personnel. They need better training so that standards are more uniform. USDA personnel working in the field need guidelines and several have told the author that they receive little or no information. Good training materials are available but they are not getting out to people in the plants.

Producers should bring in animals when they are still fit. Emaciated cattle which are too weak to raise their heads should be euthanized on the farm. Producers will stop bringing in emaciated downers if they were euthanized by plant employees before unloading from the truck or condemned by the USDA. I recommend that plant management should make sure that emaciated downers are humanely euthanized with a captive bolt as soon as the trucks pull up to the unloading dock. For both welfare and food safety reasons, these cattle should be condemned for human consumption.

Genetic Problems and Handling Downed Stressor Pigs

In one plant, a downed stressor pig was seriously abused with a Bob Cat front end loader. The operator pushed the pig along the floor. The breeding of lean pigs with large muscles has doubled and sometimes tripled the percentage of transitdeads and pigs which stress out and cannot walk (Grandin; 2000). This problem is most severe in "Bubble Butt" pigs which have huge bulging muscles, especially if they are grown to heavy weights of 280 lbs. (135 kg). At one plant which had a high percentage of "Bubble Butt" pigs they had 75 stressor downers and 13 dead on the day I visited. It was a sunny, winter day with a temperature just above freezing which is ideal weather for handling and transporting pigs. The percentage of stress downers in the plant was 1%. This problem is largely genetic and it must be solved by breeding calmer, stronger pigs. Fortunately, some pig breeders are changing to more moderate types of pigs which will be stronger. This problem must be fixed at the source, which is on the farm.

Excitable Pigs

Excitable pigs which are difficult to drive were observed in some plants. Pigs which are excitable and difficult to drive are more likely to have poor pork quality. Both genetic and environmental factors contribute to this problem. Walking in the pens at the farm will help train pigs to drive. See article on "Handling Pigs for Optimum Performance" on Excitable pigs are more likely to balk at a sparkling reflection than calmer pigs. Observations at many plants indicated that some groups of pigs were more difficult to drive than others. Excitable pigs are more difficult to handle at the plant and can cause welfare problems during handling.

Acknowledgements - The author wishes to thank the McDonald's Corporation and all the members of the supplier HACCP teams who participated in doing the audits. The efforts of the entire team have brought about significant improvements in animal welfare.


Dunn, C. S. 1990. Stress reaction of cattle undergoing ritual slaughter using two methods of restraint. Veterinary Record, 126:522-525.

Grandin, T. 2000. Livestock Handling and Transport, Edition, CAB International Wallingford, Oxon, K (In Press).

Grandin T. 1998a. Objective scoring of animal handling and stunning practices in slaughter plants. J. Amer. Vet. Med. Assoc. 212:36-39.

Grandin, T. 1998b. Feasibility of using vocalization scoring as an indicator of poor welfare during slaughter, Applied Animal Behavior Science, 56:121-128.

Grandin T. 1997a. Survey of Handling and Stunning in Federally Inspected Beef, Pork, Veal and Sheep Slaughter Plants. ARS Research Project No.3602-32000-002-08G, USDA.

Grandin, T. 1997b. Good Management Practices for Animal Handling and Stunning, American Meat Institute, Washington, D.C.

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Grandin, T. 1996. Factors that impede animal movement at slaughter plants. J. American Veterinary Medical Assoc. 209:757-759.

Grandin T. - Source of additional information on handling and stunning.

Gregory, N. G. and Grandin, T. 1998. Animal Welfare and Meat Science, CAB International Warnngford, Oxon, UK.

Humane Slaughter Act of 1978. Public Law 95-445-October 10, 1978. Federal Meat Inspection Regulations part 313, Humane Slaughter of Livestock, Section 313.2.

Warris, P. D., Brown, S. N. and Adams, S. J. M. 1994. Relationship between subjective and objective assessment of stress at slaughter and meat quality in pigs. Meat Science 38:329-340.

Watts. J. M. and Stookey, J. M. 1998. Effects of restraint and branding on rates and acoustic parameters of vocalization in beef cattle. Applied Animal Behaviour Science 62:125-135.

Weary, D. M., Braithwaite, L. A. and Fraser, D. 1998. Vocal response to pain in piglets. Applied Animal Behavior Science 56:161-172.

White, R. G., DeShazer, J. A. and Trassler, C. J. et al. 1995. Vocalizations and physiological response of pigs during castration with and without anesthetic. J. Animal Science, 73:381-386.

Table 1. Captive bolt stunning in 41 beef plants in the U.S. during 1999A
Percent stunned with one shot Number of plants Percentage of plants Line speed range
15 37% 5 to 390/hr
22 53% 29 to 390/hr
Not acceptable
2BD 5% 250 to 330/hr
Serious problem
Less than 90%
2C 5% 70 to 140/hr
A One kosher plant removed from data set.
B Cause of poor stunning was: misfiring pneumatic stunner or poor maintenance.
C Cattle slipping in stun box. There was one plant in this group that FAILED the audit because they hung a sensible animal on the bleed rail. Their stunner percentage rating is not acceptable but their total score is FAIL. There is a zero tolerance for sensible animals being hung on the bleeding rail. In this plant one operator attempted to stun 390/hr and he let the line run out of cattle in an attempt to keep up. Therefore the actual line speed was approximately 330/hr.

Table 2. Comparison of captive bolt stunning in 41 cow and fed beef plants*
Percent stunned with one shot Cow Plants, n=20 Fed Beef Plants, n=21

# of Plants Percentage # of Plants Percentage
99 to100%
5 25% 10 48%
98% to 95%
13 65% 9 43%
Not Acceptable
94% to 90%
0 0% 2 9%
Serious Problem
Less than 90%
2 10% 0 0%
* Plants that processed a mixture of fed beef and cows were put in the cow plant data. One kosher plant removed from data set.

Table 3. Vocalization percentages in 42 beef plants in the U.S. during 1999A

Number of Plants Percentage of Plants Plant Line speed range
0 to l%
19 45% 5 to 390/hr
2 to 3%
11 28% 70 to 390/hr
Not acceptable
4 to 10%
10 24% 29 to 250/hr
Serious problem
Over l0%
2 5%B 200 to 390/hr
A One kosher plant included in the data set.
B Excessive electric prodding at restrainer entrance due to balking.

Table 4. Comparison of vocalization percentages in cow and fed beef plants*

Cow Plants
Fed Beef Plants

Number of Plants Percentage Number of Plants Percentage
0 to 1%
8 38% 11 52%
2 to 3%
4 19% 7 33%
Not Acceptable
4 to 10%
8 38% 2 10%
Serious Problem
Over l0%
1 5% 1 5%
* Plants that process both cows and fed beef were placed in the cow plant category. One kosher plant included in data set.

Table 5. Causes of vocalization percentages of over 3% in 12 out of 43 beef plants that had elevated vocalization percentages
Cause of Vocalization Number of Plants % of plants in total sample
Excessive electric prod use due to balking 6 14%
Sharp broken edges in a restraint device 2 5%
Isolated lone animal left in chute or stun box for too long 3 7%
Slipping in stun box 1 2%
Electric prod too strong 1 2%
The number of plants adds up to more than 12 because one plant had more than one cause of elevated vocalization percentages.

Table 6. Electric prod use percentages in 17 beef plants scored for electric prod usage
Rating AMI Guidelines for Electric Prod Use Number of Plants Percentage of Plants Plant Line Speed Range
0 to l%
5 29% 150 to 330/hr
2 to 5%
6 35% 50 to 330/hr
6% to 25%
2 12% 70 to 100/hr
Not Acceptable
26% to 49%
2 12% 70 to 390/hr
Serious Problem
50% or more
2 12% 330 to 390/hr

Table 7. Electric Stunning of pigs in 19 plants in 1999.
Plant No.
(Nos. scrambled)
% of pigs with correct wand placement % of pigs that squeal when wand is appliedA Combined Stunning Score % Insensible on the bleed rail Rating Line SpeedB Per Hour
1 100 0 100 100 excellent 1130
2 100 1 99 100 excellent 630
3 100 1.5 98.5 100 acceptable 1020
4 100 1.5 98.5 100 acceptable 1100
5 100 1.6 98.4 100 acceptable 1050
6 100 2 98 100 acceptable 360
7 100 2.5 97.5 100 acceptable 910
8 100 Not scored none 100 acceptableC 850
9 100 Not scored none 100 acceptableC 720
10 100 Not scored none 100 acceptableC 850
11 100 Not scored none 100 acceptableC 1000
12 100 3.8 96 100 Not acceptable 970
13 100 8.5 91.5 100 Serious Problem 1100
14 99.5 0.5 99 100 acceptable 930
15 99 1 98 100 acceptable 1000
16 99 1 98 100 acceptable 1050
17 89 4 invalidD 99 FAIL 850
18 100 1.2 invalidD 95 FAIL 980
19 100 2 98 100 acceptable 1100
A The combined stunning score is calculated by subtracting points off for both wand placement errors and the percentage of pigs that squeal when the wand is applied.
B Line speed is the speed the power chain moves into the cooler.
C The percentage that squealed when the wand was applied could not be separated from squealing caused by restrainer problems or electric prods.
D Scores invalid due to a partially sensible animal on the bleed rail.

Table 8. Squeal scoring - Percentage of time pigs are squealingA
Plant No.
(Nos. scrambled)
Rating % of time squealing Line speed per hour Comments
1 Excellent 48 930
2 Excellent 53 970 Avg. of 7 groups of 100 pigs each
3 Excellent 56 850 Avg. of 5 groups of 100 pigs each
4 Excellent 70 920
5 Acceptable 78 360
6 Acceptable 83 1100
7 Acceptable 83 1050
8 Acceptable 68 1250 625/hr with 2 restrainers in same room
9 Not acceptable 94 850 Excessive electric prod use
10 Serious Problem 98 1100
11 Serious Problem 96 1020 Improved after taking away 3 electric prods to 82%
A The very smallest squeals are recorded.
B Since there were two handling systems in the same room, a conversion factor was used to determine this percentage.

Table 9. Minimum electric prod use required to keep processing full line of pigs by well-trained employees.
Plant No. % of pigs electric prodded in entire system % prodded at restrainer entrance LineB speed per hour Comments
1 5 5 630
2 12 2 930
3 14 10 1100
4 16 16 1000
5 25 25 360
6 30 5 970
7 38 6 850 Balked at reflections
8 40 - 850 Pigs backed out of chute
A All systems have races (chutes) where pigs are lined up in single file in either a single of double race (chute). No floor stunning in groups.
B All line speeds are the speed that the powered chain moves into the cooler.

Table 10. Combined stunning and squealing during handling scores for 10 pork plants with complete data in 1999.
Plant % correct stunning wand placement % of pigs squealing when stunners applied Combined stun score % time squealing Combined1 Welfare Audit Score Rating
A 99.5 0.5 99 48 99 Excellent
B 100 3.8 95 53 95 Acceptable
C 100 2 98 70 98 Excellent
D 100 2 98 78 96 Acceptable
E 100 1.5 98.5 83 96.5 Acceptable
F 100 1.6 98.4 83 96.4 Acceptable
G 100 1 99 68 97 Acceptable
H 100 8.5 91.5 98 81.5 Serious Problem
I 100 1.5 98.5 96 88.5 Serious Problem
J All scores invalid - Sensible pigs on bleed rail FAIL
1 Final rating based on combination of stunning scores and the percentage of time the pigs were squealing.

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