During twenty five years of work on livestock handling and design of restraining devices for animals, I have observed that many people attempt to restrain animals with sheer force instead of using behavioural principles. Improvements in the design of restraining devices enhances animal welfare and will reduce stress and injuries. A series of surveys conducted by the author showed that changing the design of a squeeze chute would reduce injuries to cattle (Grandin 1975). Squeeze chute design has improved. Some of the newer headgate designs may further reduce injuries. The pressure relief valve on a hydraulic chute must be set correctly. An animal restrained in a squeeze chute should be able to breath normally without straining. Under the best conditions, cattle can become bruised or injured in a conventional squeeze chute. A survey of seven major feedlots by Brown et al (1981) indicated that in five of the feedlots 1.6% to 7.8% of the animals were bruised. Even though bruises would heal by marketing time, pain and trauma may reduce weight gain. Research done by Bridget Voisinet at Colorado State University has shown that cattle that become excited and agitated in a squeeze chute will have lower weight gains and are more likely to have dark cutting meat and tougher meat. Cattle can become asphyxiated by excessive pressure on the carotid arteries. In a standard hydraulic stanchion squeeze chute used in most commercial feedyards an inexperienced operator can cause 2% of the cattle to collapse from pressure on the carotid arteries (Grandin 1980). A collapsed animal will die if the operator fails to release it immediately. Excessive hydraulic pressure can cause severe injuries. The animal's diaphragm can be ruptured (Fulton, R. 1973 personal communication). Excessive pressure can break the pelvis (Miles, D. 1992 personal communication). The author has also observed that excessive squeeze pressure can cause a significant reduction in weight gain. Good management can prevent many of these problems but there is still a great need for improved restraint devices for use on ranches and feedlots. I did not realize how poor existing chutes in feedlots were until I developed restraint devices for calf and beef slaughter plants. Quiet handling of cattle will reduce stress and injuries in squeeze chutes. Excited animals are more difficult to handle. It takes up to 30 minutes for an excited animal to calm down. To keep animals calm in a restraint device they must be calm when they enter it. Cattle should walk into a squeeze chute and walk out of it. Feedlot operators have found that calm handling of cattle in squeeze chutes will enable cattle to go back on feed more quickly.
Over the years I have designed several different types of cattle restraint devices for use in meat packing plants. During the course of developing these devices I have learned that the use of behavioural principles will keep both cattle and pigs calm. Many of these ideas could be incorporated into new designs for cattle restraining devices for the ranch farm or feedlot.
Jumat, 24 Oktober 2008
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