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Possible Effects of Embryo Transfer on Evaluation of Cows and Bulls

Animal Improvement Programs Laboratory, Animal Science Institute, Agricultural Research Service, US Department of Agriculture, Beltsville, MD 20705

ABSTRACT

Embryo transfer offers special opportunities and problems in genetic evaluations. Accurate evaluation of donors is of considerable importance. Greater accuracy in cow evaluation can come from progeny tests made possible by embryo transfer, but that information is available 4 to 6 yr after the cow already has been selected as a donor. Formulas are derived for adding daughter or son (granddaughter) data to the cow index to form a theoretically more accurate index. Addition of daughter data may introduce a bias because of the likelihood of nonrandom treatment of daughters. Adding more data to the cow indexing procedure will make results less dependent on accuracy of data from any one source. Thus, addition of dam and maternal grandsire data to data on the cow and her sire has come at an opportune time. Embryo transfer could result in substantial nonrandomness in mates of a bull, and evaluation procedures may need to be adjusted or at least suspect conditions identified. Mating each of a few donors with a number of bulls being sampled could control mate merit but only among bulls being sampled. This procedure is an example of how embryo transfer may offer opportunities for innovative, efficient sire-sampling programs. Donors and service sires used in embryo transfer thus far do not have the genetic superiority for production that will provide more than a slight increase in genetic progress.