Distractions That Impede Animal Movement

A survey of 33 Canadian, and 24 United States slaughter operations ranging from small to the very largest revealed that cattle and pigs often balk and have to be prodded excessively due to distractions that can be easily eliminated. Click here to read a current abstract on Factors that impede animal movement at slaughter plants.



Incidence of Distractions Which Impede the Movement of Livestock

Type of distraction Acceptable,
move easily
Not acceptable,
excessive balking
Lighting problems (too dim or too bright) 28 (85%) 5 (15%)
Ventilation air blowing towards approaching animals 30 (91%) 3 (9%)
Seeing movement or sparkling reflections 25 (76%) 8 (24%)

These distractions will ruin the performance of well designed restrainers and races because animals often have to be prodded when they refuse to move. Sometimes, adding more light or moving a light to eliminate sparkling reflections on floors or walls will improve the movement of pigs or cattle.

In two plants a new double rail conveyor system worked well when the plant was new, but balking at the restrainer entrance gradually worsened as the lamps over the restrainer grew dimmer with age.

Animals have a tendency to move from a darker place to a more brightly illuminated place (Grandin, 1980; Van Putten and Elshoff, 1978). The light must not shine directly in the eyes of approaching animals.

Air blowing through a stunning box entrance or down a race will make both pigs and cattle stop. Nine percent of the surveyed plants had serious balking problems caused by ventilation blowing air either out the entrance of the stunning area or down a race. Seeing people moving up ahead or jiggling gates will also impede livestock movement.







Cattle move more easily through the curved race system because they can not see people and other distractions ahead.









In one plant, cattle balked at a small chain jiggling in the race and in another, cattle balked at a shiny reflection on a vibrating metal wall. When animals are calm, they will stop and look directly at things that make them balk.

In 24% of the plants visited, animals became visibly frightened by sudden air hissing noises or extremely high pitched noises. Observations by the author indicate that high pitched noise causes more agitation than a low pitched rumble of chains and gears. The ears of cattle are most sensitive at 8,000 Hz (Ames, 1974) and they can hear up to 21,000 Hz (Algers, 1984).

Clanging and banging noises will make animals flinch or jump. Sheep slaughtered in a noisy commercial abattoir had higher cortisol levels than sheep slaughtered in a quiet research abattoir (Pearson et al.,1977). Sudden noise of a door slamming and banging on a wall increased heart rate in deer (Price et al., 1993). In the eight plants that had balking caused by noise, five were due to air hissing and three were due to high pitched motor noise. At one plant, elimination of a high pitched hydraulic whine resulted in calmer cattle. Stunning box entrance doors had hissing air in three plants. In one plant, installation silencers to stop hissing air resulted in a dramatic reduction of excited cattle.

Distractions Which Caused Pigs to Balk in the Stunning Chute and
Crowd Pen, Which Caused Increased Usage of Electric Prods
Type of Animal
Description
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.

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.

Other distractions which can impede movement are shadows, drain grates and changes of fencing or flooring types.





Drains should be located outside of the areas where animals walk. A drain or a metal plate running across an alley will cause balking.










Shadows will cause livestock to balk.










Condition of Floors in Slaughter Plants

Number of slaughter systems Percentage Flooring Condition
8 27% Excellent, non-slip floor
15 52% Acceptable floor
6 21% Slick floor, not acceptable






A good example of a non-slick surface for livestock.







References :

Grandin, T.(1996)
Factors That Impede Animal Movement at Slaughter Plants
Journal of the American Veterinary Medical Association 209 No.4 : 757 - 759

Grandin, T.(1995)

Little Things Do Matter In Debugging Animal Environments
Paper No. 954542 American Society of Engineers
2950 Niles Road St.Joseph , Michigan , 49085 USA