DETECTION OF PUTATIVE LOCI AFFECTING CONFORMATIONAL TYPE TRAITS IN ANELITE POPULATION OF UNITED-STATES HOLSTEINS USING MICROSATELLITE MARKERS

Quantitative trait loci affecting conformational type traits were stud ied in seven large grandsire families of US Holsteins using the grandd aughter design and 16 microsatellite markers on 10 chromosomes. The mo st significant marker effect was marker BM203 (chromosome 27) for dair y form in a single grandsire family. A multivariate analysis for dairy form and milk yield was also conducted, and the result was highly sig nificant, indicating that a segregating quantitative trait locus or lo ci affecting dairy form and milk yield could exist near BM203 on chrom osome 27. Marker BM1258 (chromosome 23) had a significant effect on ud der depth. A multivariate analysis on udder depth and somatic cell sco re was conducted for markers 513 and BM1258, and both markers showed s ignificant effects on these two traits, indicating that one or several quantitative trait loci affecting udder depth and mastitis might exis t on chromosome 23. Marker BM4204 (chromosome 9) had a significant eff ect on foot angle and on the composite index of traits pertaining to f eet and legs, indicating that one or several quantitative trait loci a ffecting traits pertaining to feet and legs might exist on chromosome 9. Selection on these markers could increase genetic progress within t hese families.