A Systematic Genome Search for Genes Affecting Economic Traits Dairy Cattle with the Aid of Genetic Markers

The objectives were to continue collection of semen for the US dairy bull DNA repository, to conduct a systematic search of the Holstein genome for economically significant economic trait loci (ETL), to develop and refine statistical techniques for the analysis of the data generated, and to confirm significant effects by genotyping daughters i Israel and additional US sons. One-thousand-seventy-six sons of eight US grandsires were genotyped for 174 microsatellites located on all 29 autosomes. ETL were detected for milk production traits on seven chromosomes. ETL for milk and fat yield and fat and protein percentage on BTA3 was mapped to between the markers BL41 and TGLA263. The 95% confidence interval for the ETL affecting fat percentage on BTA14 localized this ETL between the contromere and chromosome position 11 cM. This ETL was verified in the Israeli cattle population by genotyping an independent sample of cows from seven families. The radiation hybrid data for the centromeric region of BTA14 is defined by a single linkage group. Order of Type I genes within this region, CYC-FADK-TG-SQLE, is conserved between human and cattle. Thus, HSA8, the human homologue of BTA14, can be used to identify candidate genes for the ETL.