Detection of Quantitative Trait Loci Affecting Milk Production Traits on 10 Chromosomes in Holstein Cattle

摘要

Sons (n = 71 to 75) of each of six Holstein sires were genotyped at 69 microsatellite loci covering a total of 676 cM on chromosomes 3, 5, 9, 10, 13, 15, 17, 20, 23, and 26. Estimates of quantitative trait loci (QTL) effect and location were made using a least squares interval mapping approach based on daughter yield deviations of sons for 305 d milk, fat, and protein yield and fat and protein percentage. Thresholds for statistical sig- nificance of QTL effects were determined from interval mapping of 10,000 random permutations of the data across the bull sire families and within each sire family separately. Analyses combining data across sires indi- cated the presence of QTL affecting milk, fat, and pro- tein yield on chromosomes 20 and 26 and a QTL affect- ing fat and protein percentage on chromosome 3. Analy- ses within each sire family separately indicated the presence of segregating QTL in at least one family on 7 of the 10 chromosomes. Statistically significant esti- mates of QTL effects on breeding value ranged from 438 to 658 kg of milk, from 17.4 to 24.9 kg of fat, 13.0 to 17.0 kg of protein, 0.04 to 0.17/100 fat, and 0.07 to 0.10/100 protein.