An indirect marker-trait relationship occurs when the genetic marker is located near the controlling gene. Because the mark and trait are linked through association, the marker-trait relationship between two individuals may not be the same. A genetic marker has been used to detect a significance gene substitution effect for milking ability for bovine chromosome 23 in one Holstein bull. The marker-trait relationship has also been determined to be indirect. The relationship may be the same or different for other Holstein bulls or bulls in other breeds. We propose to determine whether marker loci for a second elite Holstein sire and an elite Jersey sire reveals chromosome substitution effects associated with chromosome 23. At least 5 marker loci spanning 16 cm will be used to detect recombinations and to identify animals with intact haplotypes.
Anticipated Results:We expect to obtain definitive data showing that molecular techniques can be used to identify genetic diversity directly within two dairy breeds. Genetic marker data would supplement pedigree information and increase the accuracy of selection in the absence of performance or progeny data. The overall result would be an increase in the average genetic merit of dairy cattle.
