Comparison of dams' estimated transmitting abilities from first lactation herdmates or all records of herdmates to predict sons' milk evaluations.

Multiple regression of genetic evaluations for milk yields of first lactations of 159 Holstein bulls on sire, dam, and maternal grandsire evaluations indicates that the weight for estimated transmitting ability of the dam calculated from the first record of the dam and first records of her herdmates is about as theoretically expected and is markedly superior both to estimated transmitting ability computed from the first record of the dam and all records of her herdmates and to estimated transmitting ability computed from all records of the dam and her herdmates. The latter two procedures gave similar results.