Sire by Herd Interaction in Production Traits in Dairy Cattle

Abstract

Lactation production records of 24,754 daughters of Guernsey, Holstein and Jersey sires used in artificial breeding associations throughout the United States were studied to assess the magnitude of the sire by herd inter action variance for milk, fat per cent and fat yield. Values of variance components for the individual breeds indicated sire by herd interaction variances for test to be inconsequential, with the possible exception of the Jerseys, where the sire by herd interaction variance approached the magnitude of the sire variance. The more limited data for Jerseys, however, afforded an opportunity for a larger sampling error than in other breeds. Sire by herd interaction variances for milk and fat were indicated as zero or nearly so, and positive estimates were obtained only for the Holsteins. These variances for Holsteins were approximately 1/3 and 1/5 the magnitude of the corresponding sire components for milk and fat, respectively. Limitations of the data are discussed, but inasmuch as most of the confusing circumstances would tend to augment the sire by herd variance, it is apparent that specific sire by herd differences are not of major importance in these data. The ranking of a group of bulls, based on their daughters'' performance in a given herd, would be expected to be substantially the same when these same bulls are compared on the basis of daughter performance in other herds in the same state.