- by Kay Ledbetter
Internal parasites are one of the most detrimental issues small ruminant animals deal with in Texas. Texas A&M AgriLife researchers are working to breed sheep that stay healthy and productive despite persistent threats.
Internal parasites, such as the barber’s pole worm, are the primary target of a collaborative research and education effort within the Texas A&M Department of Animal Science , led by Jake Thorne , Ph.D., Texas A&M AgriLife Extension Service statewide sheep and goat specialist and assistant professor, San Angelo.
The research is supported by a gift from Tim Turner ’77, D.V.M., and Judy Turner ’78, who established the Family of Tim R. Turner, D.V.M. ’77, and Judy D. Turner ’78 Small Ruminant Parasite Program within the department. This includes work conducted at the Texas A&M AgriLife Research and Extension Center at San Angelo and the Texas A&M Sheep and Goat Center in College Station.
“Because stomach worms are historically a large problem in the Texas sheep industry, we want to put tools in the hands of producers to better select healthier and more parasite-resistant sheep,” Thorne said.
Texas A&M AgriLife researchers are working to breed Dorper sheep that stay healthy and productive despite persistent parasitic worm threats. (Michael Miller/Texas A&M AgriLife)
Texas has a variety of production environments, which sets it apart from many other states, and sheep need to be able to thrive in all of those environments. But with a limited number of dewormers in the U.S. to treat stomach worms, the emphasis is shifting to preventative strategies, Thorne said.
The Texas A&M AgriLife Research team in San Angelo manages flocks of Dorper and Rambouillet sheep, two foundational breeds to the Texas industry due to their adaptability, maternal ability and carcass value; but they are not known for parasite resistance.
By collecting fecal egg counts and other measures of parasite response, the research is factoring in resistance to estimated breeding values, EBVs, which can then be used by producers to make genetic selection decisions.
The research team also uses this information to help with the genetic selection of sheep and goats with improved natural resistance, which is the next strategy. Researchers are identifying naturally parasite-resistant animals and using them as breeding stock to improve Texas A&M AgriLife’s flocks. Then, through ram sales, genetic progress and resistance are introduced into the industry.
“Combating parasites is a complex problem and requires a multifaceted approach to solve it,” Thorne said. “Being able to identify resistant animals, and keeping those as replacements, is a key component to help producers successfully battle parasites. But you can’t just go buy a ram and fix everything. You can’t just buy one dewormer and fix it all.
“Parasite control encompasses smart grazing management, proper use of dewormers, long-term selection of animals that don’t succumb to parasites, and enabling producers to accurately select for those animals.”
The focus on breeding for parasite resistance has also strengthened collaboration across the Department of Animal Science. Clay Mathis, Ph.D., department head, has helped champion the effort, which brings together Thorne with Shawn Ramsey, Ph.D., professor, assistant department head for academics and Texas A&M Wool Judging Team coordinator; Carey Satterfield, Ph.D., AgriLife Research physiology of reproduction researcher and professor; and sheep unit manager Allen McElroy to combine expertise in sheep production, genetics, reproduction and student education.
That collaboration has expanded the work to the Texas A&M sheep unit in College Station, where Ramsey and McElroy are leading data collection in an environment where internal parasites pose an especially persistent challenge.
The College Station work creates opportunities for undergraduate students to participate directly in data collection and breeding decisions. Exposure to the parasite challenge, and to emerging genetic and reproductive technologies being used to address it, can help prepare the next generation of sheep producers and animal scientists.
Alongside genetics, the team is evaluating management-based tools, including a feed-through product with a worm-trapping fungus and copper oxide wire particle boluses.
“Ultimately, this is research built for the people raising the flocks,” Thorne said. “Every piece — the genetics, the management tools, the breeding stock coming out of the university flocks — is aimed at putting practical, science-backed options directly into producers’ hands. We want to help Texas sheep and goat operations stay productive and profitable even where parasites are a constant challenge.”