Tips for breeding and selecting heat-tolerant cattle
Producers who make selection decisions to improve heat tolerance in their herd can positively impact their operation’s productivity and profitability. Though it may not be producers’ number one priority, it should at least be on their radar. “The point I always make is, none of us want to wear our Carhartt coats in July, but unfortunately some of the cattle genetics that we have in our herd are doing just that, they are wearing that winter coat clear into July,” Jared Decker, Ph.D., an associate professor and Wurdack Chair in Animal Genomics at the University of Missouri, said.
Hair Shedding Genetics
Researchers have spent decades studying hair shedding in different breeds of cattle. Hair shedding data and hair shedding EPD scores help producers determine how quickly an animal will shed its winter coat when the season changes from spring to summer. “We have done research looking at the genetics of hair shedding,” Dr. Decker said. “One of the interesting things about hair shedding is it is a moderately heritable trait. So, about 40 percent of the variation in hair shedding is due to genetics.”
According to Decker that means two things. First, producers can make genetic improvement simply from visual appraisal and then selecting for the phenotype or the performance of the animal. Next, producers can get accurate genetic predications quickly with less data because so much of the information is genetic in nature.
The American Angus Association now has a published hair shedding EPD, it’s indicated by HS (Hair Shedding) on an animal’s EPD charts. When collecting data on hair shedding, livestock specialists recommend making the assessment when the herd shows the most variation between animals.
Bos Indicus Genetics
According to livestock genetics specialists one of the traditional ways for producers to breed for heat tolerance is to introduce Brahman or other Bos indicus genetics into their herd. “Brahman cattle have certain adaptations to environmental stress, especially heat, that allows them to do better in those types of situations,” Decker explained.
Bos indicus breeds manage the stress of heat more effectively than other breeds because they have several adaptations that aid in heat tolerance including good blood flow at their skin and short hair. “However, there are some negative perceptions of eared cattle and so that has to be something each producer thinks about in terms of marketing those cattle and how those cattle are going to be perceived,” Dr. Decker added.
An alternative would be to add a little bit of Bos indicus genetics into the herd. “There are a lot of options now, instead of a Brangus bull that would be 3/8 Brahman you could use what they call an Ultrablack which would be only 1/8 Brahman, which would introduce a little bit of that Brahman ancestry in perhaps a more marketable calf crop package,” Decker explained.
Build from the Foundation
For producers wanting to develop a more heat tolerant herd, they can make big strides without having to start over with new genetics. “In my opinion, really the purpose of genetic tools is to take us from where we are at to where we want to be,” Dr. Decker stated. “We can do that lots of different ways and each individual producer can make a strategic plan about how they are going to get to where they want to be.”
According to Decker, producers can make fairly rapid progress just by changing their selection decisions. For example, putting an emphasis on hair shedding when selecting herd bulls or culling cattle that are slow to shed their hair in the spring. “Regardless of the trait we are trying to change, my personal opinion is we can always simply choose to change our selection process and make change that way as well,” Dr. Decker said. “It’s not that you have to scrap everything you have and start over, it’s simply changing the decisions you are making to go in a new direction.”
