Current Progressive Cattle digital edition

A genetic approach to grazing

Jaclyn Krymowski for Progressive Cattleman Published on 24 October 2018
Cattle grazing

Imagine being able to select animals for their grazing ability. The ideal result would be a herd that makes the most efficient use of their given resources, grazing as uniformly as possible throughout the different terrains and altitudes.

This type of breeding approach not only makes grazing management easier, it can also provide better protection and preservation of rangelands. These genetic advancements are much closer than you might have imagined, and grazing may be a genotype you will soon add to your breeding strategy.

A project for development of grazing distribution phenotypes, with the end goal of developing a grazing-specific expected progeny difference (EPD) and genomic evaluation, is a team effort. The collaboration is made up of New Mexico State University, Colorado State University, University of California – Davis and University of Arizona.

The joint forces in the undertaking consist of seven researchers, six graduate students and 11 ranchers contributing their animals and resources for the data collection.

Two of the researchers, Derek Bailey of New Mexico State and Milt Thomas of Colorado State, both shared their perspectives on the project with attendees of the 2018 Beef Improvement Federation Conference.

Grazing issues

While rangelands are capable of supporting the cattle on them, not all forages are equally accessible. “Usually there’s enough grass for the cows,” said Bailey. “The problem is cows graze too much in one area and not enough of another.” Bailey, a range scientist, explains that the focus is to get animals away from streams and up steep slopes and high ground.

Cattle, being selective grazers, look for where they can get the highest biomass and the most nutrients while avoiding the more labor-intensive areas. But there are some animals that show more motivation to utilize grass in harder- to-reach places.

In his presentation, Bailey explained that cattle behaviors can be split into two groups, the “hill climbers” and the “bottom dwellers.” In an ideal world, culling decisions could be made around the animals who choose to roam more for their grazing and the ones who choose to stay by the water.

“One thing I tell my students is that not all cows are created equal,” he said. “Some are willing to climb steep terrain and go all over, while some just hang near the bottom.”

In addition to the production and economic benefits, animals who graze better also play a vital role in preserving the ecology of rangelands.

“Grazing distribution is one of the five cornerstones or ‘tools’ of grazing ecology and management,” said Larry Howery, an extension specialist from the University of Arizona, another of the researchers on the project. “Along with number of animals, duration of use, season of use and kind of animal.”

By improving animal distribution, grazing pressure may be reduced in areas that are too heavily utilized. This has very broad implications because, Howery noted, rangelands occupy about 50 percent of the earth’s terrestrial surface, making it the largest land type in the world. Its preservation for future generations of beef production is absolutely paramount.

Making genomics work

Collecting the data in an effort like this is no small task. For this project, data collection is being done with global positioning system (GPS) collars on the subjected animals. Studying this type of research has gotten much more affordable as technology has advanced. Bailey noted in 1992 collars were $4,000 each. Today, a student was able to develop ones that cost only $250.

In an example of how this is applied presented in his presentation, Bailey explained that 15 cows were tracked for four-and-a-half months with positions being recorded every 10 minutes. In this case, over 19,000 locations per cow were noted as they moved and grazed throughout the day. While this data is undeniably complex, it does show distinct distribution patterns.

Even with data collection, grazing is still a trait that is difficult to harness, measure and interpret.

“In the beef industry, we have some things that are really important that we can easily measure, like weaning weight, or we can use ultrasound to measure marbling,” said Milt Thomas, genomics specialist.

“But we have a lot of really important things for beef cattle to do that aren’t so easy to measure, like grazing distribution or the ability of a calf to move into a feedlot and not get BVD [bovine viral diarrhea], those kinds of things.”

One gene Thomas is giving close attention to is GRM5, a gene that has a specific effect on grazing distribution due to its control of appetite, movement, motivation and spatial memory. He notes this is still a piece to the larger picture, with a lot of research yet to be done and more questions to be answered.

Grazing is a polygenic or quantitative trait, with literally thousands of genes and loci that influence this behavior. This is why there is a variety of disciplines working on this project. This is very unlike the simple qualitative traits such as polled versus horned.

“Our preliminary data from our last study showed that maybe five or six genetic markers accounted for [about] 33 percent of variation, and that’s the amount of genotypic variation that accounts for those genetic markers,” said Bailey. “That’s the same as heritability … But right now it might be as much as 30 percent, but we have a lot more to learn. It’s really exciting so far.

“The impacts of this technology should naturally improve the future of ranching, including animal nutrition, animal condition and productivity, and overall ranch profitability should improve as well.”

Howery said in the near future they intend to conduct outreach programs for ranchers and land managers this winter to discuss the results of this project and other grazing management aspects in New Mexico, Arizona, Nevada, California and Wyoming.

On the cattle end of the business, the feedback from ranchers on such a technology has been very positive. Bailey stated they’ve spoken to a variety of ranchers in New Mexico and Arizona, and around 80 percent said they would be willing to invest in sires with positive grazing EPDs. Anywhere cattlemen graze on public lands, they anticipate there to be interest in these advancements.  end mark

PHOTO: Some cattle are more apt to roam and utilize grass in harder-to-reach places. Staff photo.

Jaclyn Krymowski is a freelance writer based in Ohio.