Potential Impact of Bovine Somatotropin on Dairy Sire Evaluation

Use of bovine somatotropin to increase product ion of milk and milk solids poses the problem of allocation within herd and implications for genetic evaluatat ion records with and without bovine somatotropin were simulated for different correlations between performance with and without t reatment and response to it. Resulting within-herd variances and accuracy and bias in sire evaluations were compared for different t reatment strategies. Uniform allocation of bovine somato t ropin to all cows in the herd appeared to have the least potential to cause erroneous sire rankings. Random allocation of bovine somatotropin to a part of the herd is unlikely to cause serious problems in sire evaluation, although it is expected to affect cow evaluations. Systematic use of bovine somatotropin on low or high yielding cows or progeny groups may cause substantial errors in genetic evaluation.