Submitted to: Gordon Research Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: February 14, 1999
Publication Date: N/A
Preliminary analysis of quantitative trait loci (QTL) that affect milk yield, health, and conformation traits in seven large U.S. Holstein grandsire families has been completed. Predicted transmitting abilities, standardized transmitting abilities, and daughter deviations were analyzed for association with marker genotypes using analysis of variance. Strong evidence (P = 1.1 x 10-5) was found for a QTL associated with marker BM415 on chromosome (BTA6) for protein percent in a single grandsire family. Thirteen additional informative microsatellite markers from the USDA Meat Animal Research Center BTA6 linkage group covering a region from 0 to 91.3 cM were genotyped for the 74 sons in this grandsire family. Interval analyses using a simple regression method provided strong support of a QTL located 45-57 cM from the centromere on BTA6. Permutation test results provide additional evidence of a segregating QTL in this family (P < 10-5). Evidence for an effect on fat percentage was also identified in the same region (P = 0.009). Only marginal support exists for a QTL affecting milk yield (P = 0.066), while no evidence was found for effects for fat or protein yields on the region of BTA6 investigated (P = 0.465 and P = 0.744). Additional markers are required to further refine the estimates of location and allelic effects for this QTL.