Submitted to: International Conference on Animal Genetics
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 1998
Publication Date: N/A
Quantitative trait loci (QTL) affecting economically important traits are currently being identified in dairy cattle. Some of these QTL will be exploited in marker-assisted selection in which flanking genetic marker genotypes will be used to predict an animal's potential prior to progeny testing. The objective of this study was to identify QTL for milk production, health, and type traits in seven large Holstein grandsire families using the granddaughter design. The families were genotyped at 44 microsatellite markers located on 24 chromosomes. Marker allele effects were analyzed for 26 traits--19 type traits, 5 milk production and composition traits, somatic cell score, and productive herdlife. Eight markers were associated with significant effects (P < 0.001) on percent protein, productive herdlife, and several type traits. The most significant effects were found with markers BM415 (P = 0.00001) and BP7 (P= 0.00013) on chromosome 6 and BM6425 on chromosome 14 (P = 0.00002), affecting protein percentage in a single grandsire family. The latter marker was also associated with changes in milk yield (P = 0.0024) and fat percentage (P = 0.0083) in the same family. Increases in productive herdlife were associated with an allele at BM719 on chromosome 16 (P =0.0001) in another grandsire family. Selection on these markers may increase genetic gain within these grandsire families when marker-assisted selection is implemented.