Bull Genetics: Purebreds, Composites, Full-sibs and Half-sibs

Expected Progeny Differences (EPD\u27s) are currently calculated for a range of traits important to ranch profitability. These EPD\u27s are mostly used for bull selection within a breed. The list of traits for which EPD\u27s are available is certainly not complete; notable exceptions are reproduction and fitness traits plus some measure of tenderness. Across-breed EPD adjustments are available to provide a basis for comparing bulls of different breeds. EPD\u27s for composite bulls can be calculated but are mostly confined to within herd data without the benefit of data base sharing between breeds. The perceived desire for uniformity and consistency may encourage breeders to assimilate closely related bull batteries in an effort to reduce variation. The potential impact of these various aspects of bull genetics deserves thoughtful examination. This paper will highlight some of these areas for the purpose of stimulating discussion