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The beef industry is the largest revenue generating commodity in Texas and contains all segments of the beef industry in the United States (i.e., seedstock, cow/calf, stocker/feedlot, packer, and consumers). The annual volume of cattle in the Texas beef industry is strongly supported by the number of cows in the cow/calf segment, which was 4.69 million beef cows in January of 2021. Because of forage growth and stocking density, a large portion of these cows reside in counties of subtropical climate. Cattle in this environment are challenged by hot ambient temperature and humidity and the many stressors that encompass this ecosystem. Because of these environmental challenges, many of the cattle in this region of Texas are Bos indicus-influenced, which means their breed composition involves some percentage of the breed of Brahman.

The primary tool of genetic selection of beef cattle is that of Expected Progeny Difference (EPD), which merges progeny records, pedigree, and genomic information to estimate breeding values. The global beef industries have been advancing the EPD processes for > 50 years; however, there is still great need to better understand the effects of the environment on cattle, how these environmental effects are accounted in the breeding value estimation processes, and most importantly, develop new traits to foster sustainability of beef cattle production systems.


Genetic influence on beef cattle adaptation and grazing traits in a subtropical environment

Dr. Thomas is leading a new research program in beef cattle systems at the Texas A&M AgriLife Research Center in Beeville. This research will be a collaboration with the USDA’s project known as germplasm evaluation (GPE). The project will focus on evaluating Brahman-crosses, Beefmaster, Brangus, and Santa Gertrudis cattle in a subtropical environment. The project also studies the genetics of grazing traits, which meshes with the forage agronomy program at the Beeville station. The goal of this project is to increase knowledge of fitness traits of Brahman-influenced cattle in the Texas Gulf Coast region. The objectives of this project are to: 1) study and describe environment influence on cattle performance, and 2) conduct new trait development by characterizing the genetic variation of grazing traits in a subtropical environment and investigate how these traits are influenced by ambient temperature and humidity. Study of grazing traits is becoming feasible because of digital agriculture technologies.

Dr. Milton Thomas

Dr. Milton Thomas

Dr. Milton Thomas Resume/CV

Team Members

  • Jason Bosquez
  • Dr. Randy Stanko


D.W. Bailey, M.G. Trotter, C. Tobin, and M.G. Thomas. 2021. Opportunities to apply precision livestock management on rangelands. Front. Sustain. Food Sys: Agroecology and Ecosystems Services. E-pub. 611915.   doi: 10.3389/fsufs.2021.611915 

T.D.P. Paim, E.H.A. Hay, C. Wilson, M.G. Thomas, L.A. Kuehn, S.R. Paiva, C.M. McManus, H. Blackburn. 2020. Genomic breed composition of selection signatures in Brangus beef cattle. Front. Genet.: Livestock Genomics. 11:710. doi:10.3389/fgene.202000710. 

C.F. Pierce, S.E. Speidel, S.J. Coleman, R.M. Enns, D.W. Bailey, J.F. Medrano, A. Canovas, P.J. Meiman, L.D. Howery, W.F. Mandeville, and M.G. Thomas. 2020. Genome-wide association studies of beef cow terrain-use traits using Bayesian Multiple SNP regression. Livest. Sci. 232:103900; doi: 10.1016/j.livsci.2019.103900. 

T.D.P. Paim, E.H. Hay, C. Wilson, M.G. Thomas, L.A. Kuehn, S.R. Paiva, C. McManus, and H.D. Blackburn. 2020. Dynamics of genomic architecture during composite breed development in cattle. Anim. Genet. 51:224-234. doi:10.111/age.12907. 

B.C. Krehbiel, M.G. Thomas, C.S. Wilson, S.E. Speidel, R.M. Enns, S.R. Paiva, and H.D. Blackburn. 2019. Evaluation of genetic structure across U.S. climate zones using prominent AI sires of Red Angus cattle. Livestock Sci. 225:26-31. doi:10.1016/j.livsci.2019.04.012.

D.W. Bailey, M.G. Trotter, C.W. Knight, and M.G. Thomas. 2018. Use of GPS tracking collars and accelerometers for rangeland livestock production. Trans. Anim. Sci. 2:81-88; doi:10.1093/tas/txx006. 

M.A. Elzo, R. Mateescu, M.G. Thomas, D.D. Johnson, C.A. Martinez, D.O. Rae, J.G. Wasdin, M.D. Driver, and J.D. Driver. 2016. Growth and reproduction genomic-polygenic and polygenic parameters and prediction trends as Brahman fraction increases in an Angus-Brahman multibreed population. Livestock Sci. 190:104-112. 

D.W. Bailey, S. Lunt, A. Lipka, M.G. Thomas, J.F. Medrano, A. Canovas, G. Rincon, M.B. Stephenson, and D. Jensen. 2015. Genetic influence on cattle grazing distribution: association of genetic markers with terrain use in beef cows. Range Ecol. Mgt. 68:142-149.