Abstract

Detection of loci that affect quantitative traits such as milk production has been undertaken with daughter and granddaughter designs in the N.Z. dairy industry. Two other experimental designs, selective DNA pooling of trait extremes and the use of first cross Holstein-Friesian–Jersey bulls, offer the opportunity to detect more loci than the current two designs. Selective DNA pooling involves the collective pooling of DNA from daughters at each extreme (high and low) of the trait distribution. A sire family of 100,000 daughters with DNA pools created from the top and bottom 1% of progeny pooled has the same power (probability of detection) as approximately 5,000 progeny being individually genotyped with less than 1% genotyping effort. Crossbreeding in the New Zealand dairy industry opens up the opportunity to identify QTL alleles that contribute to the genetic differences between the two breeds. Identification of breed specific QTL alleles can be achieved at a power of 90% based on some 600-1500 progeny from matings of F1 Holstein-Friesian x Jersey bulls to F1 cows.

R, Spelman, N Lopez-Villalobos, and DJ Garrick

Proceedings of the New Zealand Society of Animal Production, Volume 58, , 6-9, 1998