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Sampling the Young Sire in Artificial Insemination¹

Department of Animal Husbandry, Cornell University, Ithaca, New York

ABSTRACT

Factors which determine the daughter superiority of a selected group of young sires over all those sampled have been discussed. Formulae have been developed for predicting the daughter superiority of the permanent stud and the sampling stud. The assignment of profit and cost values associated with genetic improvement for various combinations of fraction of services to the permanent stud and number of daughters for evaluating young sires revealed that the programs for maximum genetic improvement and maximum net returns were the same for the example discussed. In general, to maximize genetic improvement many young bulls should be sampled and with 20–50 daughters per bull. Consolidation of studs with 50,000 first services and using young bulls in testing herds can substantially increase the rate of genetic improvement and net returns to dairymen. Consolidation with across-the-board use of young bulls is less effective financially than with no consolidation and young bull services in testing herds only. The results indicate clearly that for maximum net returns the same number of bulls need be sampled as for maximum genetic improvement. Another set of cost and profit values might, however, exhibit a completely different picture.