Genetics can improve livestock grazing in the heatGenetics can improve livestock grazing in the heat
Project will explore genetic variation of grazing traits in a subtropical environment.
May 26, 2023
Using new fitness traits like heat tolerance and grazing behavior, Milt Thomas, Ph.D., Texas A&M AgriLife Research and the department of animal science professor in the Texas A&M College of Agriculture and Life Sciences, is determined to help improve beef cattle systems in South Texas.
Thomas, who has made a name for himself in beef cattle circles around the world, returned to his alma mater this past year to take on the beef cattle systems research program at Beeville, a part of the Texas A&M AgriLife Research and Extension Center at Corpus Christi.
He earned his bachelor’s degree in animal science and his master’s in dairy science-reproductive physiology, both from the University of Missouri, Columbia, before coming to Texas A&M University to earn a doctorate in reproductive physiology.
Thomas completed his doctoral research at the Texas A&M AgriLife Research Center at Beeville, studying beef cattle reproduction – “and that was the beginning of the age of molecular biology and DNA studies,” he said, which really propelled his interests.
“The livestock breeding world wanted to incorporate DNA technologies, and I started down that path,” Thomas said. “My interest in genomics took my wife and me around the world.”
Thomas spent 15 years in the department of animal and range sciences at New Mexico State University, NMSU, serving as the Gerald Thomas Chair in Food Production and Natural Resources. While there, he was involved in breeding Angus, Brangus and Brahman cattle for the Chihuahuan Desert.
This, he said, was a great experience to prepare for breeding Angus cattle for tolerance to high altitudes in Colorado and Wyoming when he went to Colorado State University, CSU, as a professor and the John E. Rouse Chair of Beef Cattle Breeding and Genetics in the Department of Animal Sciences.
His research collaborations at NMSU and CSU took him to Australia, New Zealand, Spain, Brazil and France before Thomas returned to his Texas roots and moved to his family’s ranch in Goliad County, near the community of Weesatche.
Building on tradition, but turning the corner
Now Thomas is using that experience to help the Texas A&M AgriLife beef cattle research program at Beeville turn a corner that will complement the more than 100 years of important intensive animal science research and 50 years of reproductive research.
“It’s time to make some changes,” Thomas said, about taking over the program. “We have changed these cattle a lot over the years, and they are very good at some things like growth and carcass size. We’ve been highly successful.”
“But our amount of knowledge and data about how one cow grazes differently than another is very minimal.”
Cattle in subtropical climates such as the Gulf Coast of Texas are challenged by high temperatures and humidity, so most are Bos indicus- or Brahman-influenced. Thomas’s latest research project will characterize the genetic variation of grazing traits in a subtropical environment and investigate how these traits are influenced by ambient temperature and humidity.
This research will be a collaboration with the U.S. Department of Agriculture, which will include moving a portion of the Germplasm Evaluation, GPE, project conducted by the U.S. Meat Animal Research Center in Nebraska to the Beeville station.
The project will evaluate Brahman-crosses, Beefmaster, Brangus and Santa Gertrudis cattle in a subtropical environment. The project will also study the genetics of grazing traits, which meshes with the long-running forage agronomy program at the AgriLife Research station in Beeville.
“Down in Beeville, it’s hot and humid, so we need heat-tolerant animals. Deciding on the animals to use for studies led us to the U.S. Meat Animal Research Center in Nebraska, one of the world’s largest animal ag research facilities. They cover every phase of animal science.”
The GPE includes 3,700 cows from the 18 most popular breeds in the U.S. Within it are the four heat- tolerant breeds – Brahman, Beefmaster, Brangus and Santa Gertrudis, which all make their home in Texas – but they were being evaluated in Nebraska.
“Now, we are collaborating, and the new home of a portion of the heat-tolerant cattle in the GPE is the AgriLife Research station at Beeville. We have already moved 120 females and seven bulls to Beeville. And, we’ll have about 60 calves born this spring. We will now do the study of the heat tolerance for this project. We will grow the calves and collect weaning weights, etc.”
Some of the heat-tolerant cattle will remain in Nebraska, so it can be better understood how much the subtropical environment of the Texas Gulf Coast influences these cattle. This type of research is called the study of gene-by-environment interaction, known as a G x E project.
Hilltoppers or bottom dwellers: It’s all in the genes
Thomas said over the years, the genetic selection of beef cattle has helped livestock performance improve. The primary tool of genetic selection of beef cattle is expected progeny difference (EPD), which merges progeny records, pedigree, and genomic information to estimate breeding values. For EPD, the environmental effects are adjusted out by contemporary grouping, which compares the genetics of cattle raised at the same location, age and sex, etc.
“However, there’s still a great need to better understand the effects of the environment on cattle, how these environmental effects are accounted for in the breeding value estimation processes, and most importantly, develop new traits to foster sustainability of beef cattle production systems.”
Specific examples he gave of fitness traits that have received investment in the past five to 10 years are feed efficiency and greenhouse gas emissions, hair-shedding, susceptibility to bovine respiratory disease, pulmonary arterial pressure for high mountain disease and feedlot heart disease, cow longevity and grazing distribution.
The one thing Thomas said they will bring new to the GPE is grazing traits, or sustainability traits. That meshes well with the forage and agronomy grassland scientific team led by Jamie Foster, Ph.D., AgriLife Research forage agronomist in Beeville.
Thomas said the concentration on the genetics of grazing distribution continues his research in the western U.S. funded through a USDA program called Western Sustainable Agriculture Research and Education (WSARE).
“We observed hilltoppers and bottom dwellers, as there are cows that are lazy and hang around the water trough and those that go take a hike every day – and that’s where our data and results revealed a big genetic component to explore. We’re at a phase in the history of agriculture where we always talk about sustainability.”
He said cattle need to do better in the future by walking around and eating grass, as opposed to the ones that just stand around waiting to be fed. “How sustainable is it when we have to deliver expensive feeds to these cattle that could make it by being better at grazing?”
Building on 50 years of reproductive research
Moving forward, Thomas said the research program at the AgriLife Research station in Beeville will be about beef systems – combining beef reproduction with extensive grassland and forage agronomy work. If part of the research team is studying the health of the grassland, what better way to work with them than find out more about the animals grazing that land.
He said he found when studying the genetics of grazing with western ranchers that one of their challenges was their landscape included running water, but the grazing lease typically was owned by a public entity.
“There was lots of concern by those public entities about cows being in the riparian areas – creeks and streams and rivers. There was need to keep those cows out of the water and degrading stream health and habitat. In surveys, ranchers were willing to pay more money for bulls if they knew the bull would sire daughters that were hilltoppers rather than bottom dwellers. South Texas has the same type of interest – how to manage the landscape better. Cows are cows; we know they will always overgraze part of the pasture and under graze other parts. The more that cow will do on her own, the more sustainable that system is.”
Thomas said when the AgriLife Research station in Beeville started studying beef cows, most cows weighed 1,000 pounds or less. Today, cows weigh 1,300 to 1,500 pounds. That’s where the sustainability issue comes in – the cost and how they impact the land. GPE animals are an ideal set of animals to study this. The study includes not only the four heat-tolerant breeds but also involves the Hereford, Red Angus and Charolais breeds.
“We started bringing GPE cattle to the Beeville station in January, and the first calves are being born now. There are 60 cows, 60 heifers and seven bulls. We already have the first data points, birthweights on the calves as they’re born. And the heifers were weaned in Nebraska, and we are collecting hair-shedding scores on them as the temperature warms this spring.”
Next, they will implement two different tools to determine grazing patterns. One is an ear tag with a solar device that will send GPS signals on a cow’s location and how much she is moving. The other device is a bolus placed in the rumen with a receiver at the water trough uploading data to a cloud-computing system. This accelerometer will tell us how much the cow moves, when they drink water, and their body temperature.
“The larger beef cow needs more grass to eat, and most of the systems we water our livestock with are way outdated. We are no longer watering a 1,000-pound cow anymore, but sometimes a 1,500-pound lactating cow and calf. A cow of this size nursing a calf needs 30 gallons of water per day. We need to make sure our water troughs are big enough.
“When we start releasing a lot of these data and results, I think the ranching community is going to be somewhat alarmed that we need to do some things differently,” Thomas said.
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