Characterization of DNA Polymorphisms in Three Populations of Hereford Cattle and Their Associations with Growth and Maternal EPD in Line 1 Herefords

Three populations of Hereford cattle differing in inbreeding levels and genetic potential for growth were genotyped for seven DNA polymorphisms. The populations were compared to determine differences in allele frequency and genetic variation. Significant differences in allele frequency among the populations were found at six of the seven polymorphisms genotyped, and average genetic variation differed as expected when inbreeding levels were considered. Effects of several polymorphisms on growth and maternal EPD were evaluated for one population (Miles City Line 1 Herefords) using regression analysis. Substitution of a B allele for an A allele of the kappa-casein polymorphism accounted for significant decreases in direct birth weight and maternal 180-d gain from birth to weaning EPD, explaining 15% and 8%, respectively, of EPD variability. Several other significant effects accounting for small portions of EPD variability were also detected.