General Session I

Selecting for Temperament

Texas A&M's Ron Randel explained the advantages of using different temperament-scoring systems as a selection tool.

by Kasey Miller for Angus Productions Inc.

 

HOUSTON, Texas (April 19, 2012) — Gauging temperament has many important ramifications for cattle performance and handler efficiency, Ron Randel, professor of animal science at Texas A&M University, told participants of the Beef Improvement Federation (BIF) symposium in Houston, Texas, April 18-21.

 

“Temperamental cattle are more easily stressed than calmer cattle,” Randell said.

He defined temperament as the reactivity or fear response to humans. Temperamental cattle pose more of a risk of injury to handlers and other cattle, and also have reduced feed intake, average daily gain, intramuscular fat, carcass quality and response to vaccination. Additionally, carcasses of temperamental cattle have increased shear force values and bruise trim, and a higher percentage are dark cutters.

 

If temperament is so vital, how does one measure it? Randel suggested using the docility score, the pen score, exit velocity and the McGregor Genomics Project system.

 

Docility score, also termed a chute score, evaluates a calf’s temperament when processed in a chute using only head restraint (no squeeze applied), Randel said. The calf should be evaluated about weaning time, or shortly after. Docility scores range from 1 (docile) to 6 (very aggressive).

 

The advantages of this method, he explained, are ease of use during routine handling and a positive correlation with temperament. However, it is not correlated with cortisol concentration in the blood, which affects stress levels and meat quality.

 

Pen scoring involves evaluating a small group of calves, about five or so, in a relatively small pen. Two observers evaluate the calves’ responses, he explained. The range for a pen score is from 1 (non-aggressive) to 5 (very aggressive). This method is correlated with blood cortisol levels and other measurements of temperament. It does require an additional handling of the calves, but it is an easy way to determine temperament when deciding to buy cattle or when sorting cattle, Randel noted.

 

“You’re not looking for the most docile, you’re looking for the crazy one to eliminate that tail of the bell curve,” Randel said.

 

Exit velocity is another good way to gauge temperament, he said, but is more laborious. Exit velocity is established by measuring the time it takes a calf to travel 6 feet (ft.) when exiting the chute. It is an objective method of evaluation, and it correlates with temperament and concentrations of cortisol in the blood. On the other hand, it can be more cumbersome, requiring equipment to measure, and it isn’t indicative of all measurements of temperament, such as aggression. It could also just mean that the calf is afraid of being alone. He added that temperamental calves’ exit velocity increases with their age.

 

The most in-depth temperament-scoring system is the McGregor Genomics Project system. In this system, Randel described, four evaluators assign disposition scores postweaning. Two evaluators are located at each end of an alley that is about 12 ft. wide and 75 ft. long. Calves are kept in a pen near the evaluation alley and brought into the alley two at a time to be evaluated. The calves are returned to the pen after two minutes. Each animal is scored from 1 (non-aggressive) to 9 (extremely aggressive) for aggression, nervousness, flightiness, gregariousness and overall temperament.

 

Temperament is heritable, much like carcass traits, Randel said, so improvent can be made with selection. While the McGregor Genomics Project system is great for researchers, it’s not the most practical for producers. Pen scoring has the highest heritability and does not require any purchase of equipment, so he recommended that system if only one can be used.

 

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