J. Anim Sci.
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J. Anim Sci. 1989. 67:2863-2871.
© 1989 American Society of Animal Science
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Multiple Ovulation and Embryo Manipulation in the Improvement of Beef Cattle: Relative Theoretical Rates of Genetic Change1

W. W. Gearheart, C. Smith and G. Teepker

University of Guelph2, Ontario, Canada N1G 2W1

Abstract

Theoretical rates of annual genetic responses to selection in beef cattle were compared for conventional and multiple ovulation and embryo transfer (MOET) breeding schemes. Several combinations of replacement policy, mating ratio and type of selection were considered for both schemes with low, medium and high heritabilities. For MOET, four rates of embryo transfers per donor were used to represent low to moderate MOET levels. The results indicated that annual genetic responses to selection could be up to 1.3, 1.6 and 1.8 times as great for MOET compared with conventional breeding for traits of low, medium and high heritability, respectively; however, the annual inbreeding rates also were high for the MOET schemes considered. Embryo splitting, or cloning, was shown to increase accuracy of selection by 8 to 35% through the production of identical genotypes. The use of MOET in conjunction with embryo splitting in elite nucleus units could substantially increase genetic improvement for traits with low, medium and high heritabilities in beef cattle populations.

Footnotes

1 This research was supported by the Ontario Ministry of Agriculture and Food, by the Natural Sciences and Engineering Research Council of Canada and by Semex Canada.

2 Centre for Genetic Improvement of Livestock, Dept. of Anim. and Poult. Sci.






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Copyright © 1989 by the American Society of Animal Science.