How to Track Down the Cause of Bruising

by Temple Grandin, Ph.D.
Assistant Pr6fessor
Colorado State University
Fort Collins, CO, 80523

Bruises cost both the cattle and the pork industry millions of dollars annually. A recent Non-Fed beef audit showed that 22% of cull cows have severe bruising. Even in fed beef up to half of the carcasses will have bruises. Since it is impossible to determine the age of recent bruises, how can plant management determine whether or not a bruise occurred inside or outside of the slaughter plant? You have to look for different patterns of bruising.

If a bruise is occurring in the plant it will usually occur on the same location on cattle from many different sources. In one beef plant they started to notice bruises on the left shoulder. They were occurring on cattle from many different feedlots and they were gradually getting worse. The cause of the shoulder bruises was worn out broken metal in the restrainer entrance. Cattle are very abrasive and over a period of several years they wore through the metal side of the restrainer and a sharp edge was created. The first place one should look if there is a bruise on cattle from many origins is broken or damaged parts in the chutes, restrainer or stunning box. Rough handling can also cause bruising to increase. Back bruises caused by slamming stunning box doors on cattle are an indicator of rough handling. Some of the pork plants have eliminated back bruises caused by guillotine gates by cutting off the bottom of the metal door and replacing it with a curtain made from conveyor belting. The animals think that the conveyor belting is solid and they will not attempt to go through it.

Tracking down bruises which occur outside the plant will require a little more detective work. Somebody has to observe many carcasses on the line to determine if a particular type of bruise is occurring only on cattle from a specific origin. For example, there may be a severe bruise on the right loin of cattle from Feedlot A. A trip to the feedlot indicated that there was a sharp metal strip that protruded in their loading ramp. One over looked factor is the variable of truck driver. Poor driving habits, such as slamming on the brakes and sudden acceleration can increase bruising because cattle are thrown off balance. Check to make sure that, a truck driver is not the cause. Suspect a truck driver if some of the cattle from Feedlot B have bruises and other loads of cattle from this same feedlot have low levels of bruising. This may indicate that one driver is causing bruises and the other drivers are doing a good job. Several feedlots have banned the use of electric prods for truck loading. This has resulted in less bruising and fewer dark cutters. Another cause of bruising from a particular origin is excessively wild cattle. Wild cattle that are not accustomed to a person on foot will often have more bruises and dark cutters. Cattle should be exposed to people on foot long before they arrive at a packing plant.

Old Bruises and Fresh Bruises

Even though it is not possible to determine the age of a bruise that is under 24 hours old, it is possible to separate bruises into two catagories. Fresh bruises and bruises that are several days or weeks old. I was hired to consult with a plant that had severe bruising on cows. They were ready to rebuild their entire facility to get rid of bruises. I took one look at the bruises and realized that they were old and that they had probably occurred at the many auctions the cows had gone through. Old bruises have a clear yellow mucous. Fresh bruises do not have yellow mucous. If you observe yellow mucous the bruise will be several days or weeks old.

In another case, pork loins had bruise damage and the plant manager thought that the bruises were caused by the stunner. The loin damage had yellow mucous on it and had happened about a week ago when the pigs were sorted. When I looked at the carcasses on the kill floor I observed marks where the pigs had been beaten with metal gate rods. The gate rod marks were in the same location as the yellow mucous on the loins.

Ye1low mucous which is an indicator of an old injury can remain on the carcass for months. At a fed beef plant I observed some faint traces of yellow mucous on the legs at the point where the meat hooks are inserted. When I called the feedlot I learned that these cattle had been severely abused during handling at a stocker operation prior to entering the feedlot. The manager told me that many of the cattle fell down when they exited from the squeeae chute.

Tracking down the cause of bruises will take some time, but you will be rewarded by reducing losses and improving animal welfare.

Bruise Pattern on the Carcass

The cause of a bruise can often be determined by the pattern of damage on the carcass. In all species, severe damage where a large portion of the carcass is completely wrecked is often an indicator of the animal being trampled in a truck. A common cause of trampling is over loading of trucks. In an over loaded truck the downed animal is not able to get back up. Bruises that are deep and about 8 inches (20 cm) in diameter are often caused by horns. Horned cattle will have twice as many bruises as dehorned cattle. Tipping of the horns by cutting off the horn tips will not reduce bruising. Horns should be removed from baby calves before they grow horns. Another factor in bruising is the structure of the marketing system. Cattle that are sold on a live weight basis where the packer pays for the bruises will have twice as many bruises compared to cattle sold in the carcass where the producer pays for the bruises. Holding people accountable for losses will greatly reduce bruising. People are more careful when they have to pay for it.

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