Abstract

Growth of artificial insemination (AI) sampling programs in the United States and changes in genetic merit of bulls that enter AI were examined. For Holsteins, 113 bulls were Al-sampled in 1960, 227 in 1970, 912 in 1980, and 1,082 in 1983; 93 Holstein bulls were progeny tested through natural service prior to entering AI in 1960, 43 in 1970, 43 in 1980, and 44 in 1983. Genetic merit of young bulls that enter AI progeny-test programs has been increasing more rapidly in recent than in earlier years. Estimated transmitting ability of Al-sampled bulls increased 60 kg per year from 1980 to 1983. Combined increase in number and genetic merit of Al-sampled bulls should bring the annual rate of genetic improvement to over 1.5 percent (presently at 1 percent). Accuracy of pedigree information in predicting bulls' progeny yield was examined. Estimated transmitting ability of sires was a more useful predictor than that of dams or maternal grandsires. An index that combined sire, dam, and maternal grandsire information was the best predictor for Holsteins and Jerseys.
 

H. D Norman, R. L Powell

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume IX. Breeding programs for dairy and beef cattle, water buffalo, sheep, and goats., , 196–201, 1986
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