Keep Calm Replacements In Your Herd

Everyone knows that high-strung animals can be dangerous to workers and hard on facilities. But “temperament is not just a convenience trait. It’s truly an economic trait,” says Dr. Ron Randel from Texas A&M.

A research team made up of scientists from the Agricultural Research Service’s Livestock Issues Research Unit (LIRU) in Lubbock, Texas, Mississippi State University (MSU) and Texas A&M has been studying the effects of temperament on physiological processes of beef cattle.

“[Temperamental] animals themselves are programmed differently. We know that there are differences in immune systems of these animals, we know that there are differences in metabolic responses of these animals and we know that overall performance is different in these animals,” says Dr. Jeff Carroll, LIRU research leader.

For example, temperamental animals aren’t as likely to show signs of illness. Because of this, they don’t get treated and act as disease carriers. They also don’t build immunities in response to vaccinations as well and they don’t gain weight as readily after weaning.

These reasons make it all the more important to keep temperamental animals out of your herd. This same research team found two methods that are used to create a temperament score and allow producers to know which cattle to cull.

“I think [the temperament score] is very practical, especially if they’re looking at keeping replacement animals, and they want to make sure that they’re weeding really high-strung, temperamental animals out of their herd,” Carroll says.

Randel recommends that replacement heifers be scored at weaning time, which is usually the first time they are handled.

The first scoring method, the exit velocity score, is measured using rodeo timing equipment. The speed at which the calves leave the chute is measured in meters per second.

“A calf can not go much faster than about 5 meters per second,” Randel says. “In fact, the fastest ones we usually see are about 4.2, 4.3 seconds.”

The second scoring method is called pen scoring. Groups of three to five calves are put into pens, and an observer will go into the pen with them and score their temperament from one to five.

“If the animal is very docile, it may even approach the observer, then we’d score that animal, say, at one. If the animal, however, is avoiding the observer, running around the pen with its head held high, then it’d probably be considered a three. Now, animals that would be in the category of a four or five, which we’d consider really wild animals, are those that are completely avoiding the observer, running around trying to break out of the pen, or maybe even running past the observer,” says Carroll.

The two scores are then averaged to produce the temperament score.

“The pen score will get some of the aggression, but exit velocity will not pick up aggression. It picks up fear,” Randel says.

The team tested cortisol levels in the blood (a stress hormone) and correlated it with these scoring methods to see how accurate they actually were. Both methods were found to be highly correlated with cortisol levels.

Randel suggests that if there is time for only one of the scoring methods, that the pen scoring method should be used since it has the highest heritability.    

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