United States Department of Agriculture-Dairy Herd Improvement Association sire summary information on bulls active in artificial insemination in May, 1966, and May, ]968, was combined with results on the relation of Predicted Difference for milk yield to income over feed cost in first lactation of daughters of artificial insemination bulls in the Beltsville herd, to show present status and changes over this two-year period, in the merit of artificial insemination bulls to raise milk and milk fat yield and income over feed cost. Mean Predicted Differences for milk (kg), milk fat (kg), and extra income over feed cost in first lactation ($) for bulls active in artificial insemination on January 1, 1968, were: Ayrshire, 156, 5, and 11; Guernsey, 82, 3, and 6; Holstein, 96, 4, and 7; Jersey, 65, 3, and 5, and Brown Swiss, 41, 2, and 3. The data indicate genetic progress from the use of artificial insemination could have been much higher. Suggestions for increasing the rate of future progress are given. Evidence is presented to show that these suggestions are feasible and should result in dramatic increases in average genetic merit for yield in artificial insemination bulls.
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Dickinson et al. (1969) studied this question.