Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract only
Publication Acceptance Date: 3/1/2005
Publication Date: 7/1/2005
Citation: Thallman, R.M., Cundiff, L.V., Bennett, G.L. 2005. Experimental design for estimation of breed, heterosis, and qtl effects in cattle [abstract]. Journal of Animal Science Supplement 83(1):104. Interpretive Summary: No interpretive summary is required.
Technical Abstract: Generation of data to provide ties between breeds and breed-specific heterosis estimates for support of multibreed national cattle evaluation has become a primary objective of the Germplasm Evaluation Program (GPE) at the U.S. Meat Animal Research Center. Consequently, more emphasis will be placed on continual re-sampling of highly influential purebred sires with high accuracy EPD. A change in design that incorporates the following elements is being considered: Purebred cows and cows 75% or slightly more of their sire breed (SB75) would be bred AI to bulls of a different breed to produce progeny 50% or slightly more of their sire breed (SB50), which would in turn be bred AI to bulls of their sire breed to produce SB75 progeny. Approximately 25% of the cow herd would be purebreds of four breeds, 40% would be SB50, and 35% would be SB75. All AI sired heifers would be retained in the herd for maternal evaluation and (with the exception of some purebred cows) all cows would be AI-sired. Substantially greater information can be generated from the same number of cows by designing the population in such a way that every calf contributes to estimates of both direct and maternal effects. This design would provide a set of powerful resource populations with extensive phenotypes for detection and characterization of QTL. Sampling highly influential sires would ensure that the population segregated most polymorphisms relevant to the U.S. beef industry. Progeny of F1 cleanup bulls would contribute directly to project objectives by providing large paternal half-sib families with complete carcass phenotypes. Different subsets of the population would be most effective for each of several genomics objectives. Direct and maternal breed-specific heterosis, as well as breed effects and QTL effects, should be estimable under the proposed design using a model accounting for breed contributions and expected heterozygosity. Using the same population for several complementary objectives is the most efficient use of limited resources.