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Bovine Temperament: A Feedlot Focus

August 13, 2014
BT Feedlot Cattle
Researchers examine how temperament of cattle could affect their immune function and carcass merit.  
 
 

Researchers examine how temperament of cattle could affect their immune function and carcass merit.
By: Katie Allen, K-State Research & Extension News

As a new load of weaned calves enters the feedlot, workers prepare to process the calves upon arrival. Processing would likely include vaccinating these calves to prevent respiratory disease and treating them for parasites, among other regular processing procedures. Many handlers would acknowledge that the calves with more docile, or calm, temperaments are much easier and safer to process.

Cattle producers of all types—from the cow-calf, stocker and feedlot sectors—historically have selected for and preferred to manage calmer animals not only because they are safer for handlers to be around, but they also seem to gain weight faster and have fewer health issues.

Recent research involving many universities, including Kansas State, examined the genetics of bovine temperament and how it relates to two important aspects of production: immune function, specifically animals’ susceptibility to bovine respiratory disease (BRD), and carcass merit. It found, as previous research has also indicated, that temperament is a moderately heritable trait producers can select for in their herds.

Bob Weaber, beef breeding and genetics specialist for K-State Research and Extension and one of the researchers on the project, said this study showed that animals with a more favorable temperament gained better on feed compared to more excitable animals. Because of this, they were overall more mature at harvest and seemed to have carcass fat, which is desirable to an extent for better quality grades. But, at extreme levels, the extra fat is undesirable for both quality and yield grades.

Temperament and its relation to the disease component of the study was a little harder for the researchers to separate, he said, and yielded some somewhat surprising findings.

About the study
Weaber worked with many other researchers on the project that was led by Mark Enns, professor of animal sciences at Colorado State University. They collected data in 2007 and 2008 as part of a large study to look at the genetics of feedlot cattle health.

"It was an involved project in that it took a lot of human hands to pull off," Weaber said. "We processed data on more than 2,500 head of steers fed in southeast Colorado during those two years."

It took the researchers about five days to process the cattle upon arrival at the feedlot, he said. Ultrasound information helped the researchers determine the animals’ body composition, both when they were placed on feed and at subsequent processing about 80 days into the feeding period. The researchers also collected temperament data at these times and monitored the animals closely for disease, specifically BRD, at all times.

The researchers measured temperament in two ways: chute score and exit velocity. The chute score scale defined by the Beef Improvement Federation ranges from 1 to 6, where calmer animals are at the lower end and most aggravated cattle, the ones Weaber said "test every weld on the squeeze chute," are at the higher end.

"In this case, most of the animals scored 2, 3 and 4, which is typical of beef cattle categorization in the United States," he said.
Exit velocity was calculated based on the time it took an animal to cover a defined distance of 6 feet, after it was released from the chute.

Additionally, a blood sample from each animal was taken during processing to examine concentrations of cortisol and interleukin-8 (IL-8). High levels of cortisol indicate stress in cattle, while high levels of IL-8 show a more active or functional immune system, Weaber said.

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