2011 Annual Report
OBJECTIVE 2. Examine potential interactions of genetically diverse breeds of cattle with climatic or nutritional environments.
OBJECTIVE 3. Evaluate breeds to create an easy-care maternal line of hair sheep for use in low-input production systems. Sub-objective 3A. Evaluate wool and hair breeds in intensive and low-input production systems during traditional fall breeding and for fertility during challenging spring breeding. Sub-objective 3B. Evaluate life-cycle productivity of reciprocal crosses between the Romanov and Rambouillet breeds. Sub-objective 3C. Create an easy-care maternal line of hair sheep.
OBJECTIVE 4. Evaluate power of experimental designs to estimate quantitative and molecular genetic parameters.
OBJECTIVE 5. Develop statistical theory and computational algorithms to incorporate DNA information and multi-breed comparisons into genetic evaluations of beef cattle.
The first three objectives use experimental populations to provide genotypic and phenotypic data for traits known to affect life-cycle efficiency and for matching genetic resources with specific marketing and production situations. Large-scale beef cattle and sheep experiments using both quantitative and molecular approaches are planned to provide genotypic and phenotypic data for estimation of genetic effects on fundamental traits. Cattle research will emphasize multi-breed genetic evaluation, estimation of genetic parameters within breed, and structuring of populations to facilitate genomic research leading to development of DNA tests for economically important traits. A population of cattle is being developed for QTL identification that has recent ties to industry genetics, several half-sib families large enough to contribute to identifying QTL through linkage, and many smaller families and several potential origins of QTL allowing fine mapping, association analyses, and marker validation. Potential interactions of temperate and tropically-adapted cattle breeds with temperate and subtropical environments will be investigated through evaluation of F1 cows consistent with commercial production systems in the subtropical environment of Louisiana and the temperate environment of Nebraska. Sheep experimentation will focus on breed evaluation, leading to creation and development of an easy-care maternal line of hair sheep.
The animal experiments will be complemented by research to develop and apply statistical technologies required for discovery, estimation, and use of genetic effects, including incorporation of genetic markers into multibreed genetic evaluations for beef cattle. The fourth objective addresses designs of experimental populations for estimation of genetic effects. Various mating plans will be simulated and evaluated for their power to detect QTL effects of various sizes, power of detecting breed-specific heterosis, and for the standard errors of other genetic effects. The final objective focuses on the development and application of statistical theory required for analysis of data and exploitation of genetic effects by livestock industries. Whole genome selection will be investigated as a method to reduce bias and improve accuracy of genetic prediction.
About 180 highly influential bulls were newly sampled from the beef industry to produce progeny in the Germplasm Evaluation Project. The South Devon and Tarentaise breeds were added for the first time since the 1970s. Cows were mated to sires sampled from the 18 largest beef breed associations with genetic evaluations using artificial insemination: Angus, Hereford, Simmental, Charolais, Limousin, Red Angus, Gelbvieh, Shorthorn, Brangus, Beefmaster, Maine-Anjou, Brahman, Chiangus, Santa Gertrudis, Salers, and Braunvieh, South Devon and Tarentaise. Since its beginning, the project has produced 2,000 2-breed cross calves and 800 backcross calves. The project also produced 96 0.875-blood calves representing an important milestone toward the objective of grading up to purebreds of each breed in the project. Steer and heifer progeny from artificial insemination mating to these sire breeds were measured for feed intake. Carcass data and beef tenderness were collected on the steers. Heifers were retained for reproductive performance assessment and to continue producing calves that will contribute to estimation of breed differences, heterosis, and genomic marker effects.
Pooled DNA samples from animals with extreme phenotypes are being used to detect marker associations for reproductive traits and disease resistance traits (lung lesions, pneumonia treatment records, and bloat treatment records). These procedures, already applied in human case control studies, have the potential to improve marker association testing on large phenotypic databases with minimal costs.
An experiment was completed to compare productivity of Rambouillet x Romanov reciprocal crossbred ewes through four years of age when mated to two terminal sire breeds. We continued to increase flocks of Katahdin and Polypay sheep as industry standards for easy-care maternal breeds of prolific hair and wool sheep, respectively. Over 1,950 lambs of an easy-care maternal line of prolific hair sheep (0.5 Romanov, 0.25 White Dorper, 0.25 Katahdin) were produced. Rams in this line were genotyped and selected to increase resistance to scrapie and ovine progressive pneumonia.
Kuehn, L.A., Keele, J.W., Bennett, G.L., Mcdaneld, T.G., Smith, T.P., Snelling, W.M., Sonstegard, T.S., Thallman, R.M. 2011. Predicting breed composition using breed frequencies of 50,000 markers from the U.S. Meat Animal Research Center 2,000 bull project. Journal of Animal Science. 89:1742-1750.
Lindholm-Perry, A.K., Kuehn, L.A., Snelling, W.M., Smith, T.P.L., Ferrell, C.L., Jenkins, T.G., Freetly, H.C. 2010. Polymorphisms in POMC are not associated with dry matter intake and average daily gain phenotypes in beef cattle. Animal Genetics. 41(6):669-670.
Wheeler, T.L., Cundiff, L.V., Shackelford, S.D., Koohmaraie, M. 2010. Characterization of biological types of cattle (Cycle VIII): carcass, yield, and longissimus palatability traits. Journal of Animal Science. 88:3070-3083.
Zhang, S., Knight, T.J., Reecy, J.M., Wheeler, T.L., Shackelford, S.D., Cundiff, L.V., Beitz, D.C. 2009. Association of polymorphisms in the promoter I of bovine acetyl-CoA carboxylase-alpha gene with beef fatty acid composition. Animal Genetics. 41:417-420.
Thrift, F.A., Sanders, J.O., Brown, M.A., Brown Jr., A.H., Herring, A.D., Riley, D.G., Derouen, S.M., Holloway, J.W., Wyatt, W.W., Vann, R.C., Chase, C.C., Cundiff, L.V., Baker, J.F. 2010. Review: Preweaning, postweaning and carcass trait comparisons for progeny sired by subtropical adapted beef sire breeds at various U.S. locations. Professional Animal Scientist. 26(5):451-473.