Evaluation of Progeny Tests of Dairy Sires in Single Herds

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Abstract
First-lactation Holstein-Friesian HIR records of 37,890 animals were studied for the usefulness of average deviations of daughter records from contemporaries to estimate breeding values of sires whose daughters are in one herd. Breeding values based on daughters' deviations were termed unadjusted breeding values. The added usefulness of the dams' deviation from their contemporaries to adjust for selection of mates of sires also was examined. Breed- ing values adjusted for the deviations of the sires' mates were termed adjusted breeding values. Breeding values from Dairy Herd Improvement Association rec- ords including artificially sired daughters for 99 of the 1,355 sires involved were compared with the unadjusted and adjusted breeding values. Comparisons of the unadjusted and ad- justed breeding values with estimates of breeding values based on the average of daughter records indicated that both are more efficient than the daughter average. The adjusted had slightly more precision than the unadjusted breeding value, and it was corrected for possible effects of selec- tion of dams. These effects do not appear to be important for comparisons among groups of sires with single-herd proofs, since rank correlations between unadjusted and adjusted breeding values were 0.978 for milk and 0.972 for per cent fat. Results of the theoretical and actual comparisons of the single-herd proofs with the breeding values from Dairy Herd huprovement Associations were in close agreement. The rank correlation between the single-herd proofs and the AIBV's for the 99 bulls