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Predictability of Breeding Efficiency in Dairy Cattle¹

Kentucky Agricultural Experiment Station, Lexington

ABSTRACT

The breeding efficiency of 6,509 cows and for 2,403 herds was compared for 2 consecutive yr. As the number of services required by cows the first year increased, these was a rather unifrom in the average number of services requiewd the second year. However, the differnces were not great, increasing approximately 0.1 service for each service increase of 1.0 for the first year. Nearly 55 per cent of the cows required the same number of services both years. The correlation between breeding efficiency for consecutive years was 0.084 ± 0.012.

The predictability of breeding efficiency of herds was about the same as that for cows. About 54 per cent of the herds required approximately the same average number of services per cow both years. Only 9.3 per cent the "problem herds" (averaging 2.1 or more services per cow) were still problem herds the next year. The total number of problem herds remained about the same both years, i.e., 7.1 per cent the first year and 5.9 per cent the second.

¹ The investigation reported in this paper is in connection with a project of the Kentucky Agricultural Experiment Station and is published by permission of the director.

² The authors wish to acknowledge the assistance of Marshall Carpenter, Manager of the Kentucky Artificial Breeding Association, for furnishing records used in this study and to James T. Johnson, student at the University of Kentucky, for assisting in tabulating records.