Submitted to: Plant and Animal Genome VX Conference Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: December 1, 1996
Publication Date: N/A
Technical Abstract: Quantitative trait loci (QTL affecting economically important traits are currently being identified in dairy cattle. Some of these QTL will be used to implement marker-assisted selection in which 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 calving case and the type traits in seven large Holstein families using the granddaughter design. Sixteen microsatellite markers located on ten chromosomes were used to genotype grandsires and their sons using the granddaughters' phenotypic values as the trait endpoints. Using results analyzed within family, each of two markers (BM203, chromosome 27; BM1443, chromosome 23) was associatd with a significant effect (P <0.01) on calving ease in one family. Due to the large number of evaluated traits, composite indices were used to identify potential QTL for the type traits. Four markers (located on different chromosomes) were associated with significant effects (P <0.001) on the feet and legs, dairy and udder composite indices in four different families. After verification of these QTL, producers may be able to manipulate these QTL to improve calving ease and body conformation in these large Holstein families.