A genome scan for QTL influencing milk production and health traits in dairy cattle

Abstract

A genome scan was conducted in the North American Holstein-Friesian population for quantitative trait loci (QTL) affecting production and health traits using the granddaughter design. Resource families consisted of 1,068 sons of eight elite sires. Genome coverage was estimated to be 2,551 cM (85%) for 174 genotyped markers. Each marker was tested for effects on milk yield, fat yield, protein yield, fat percentage, protein percentage, somatic cell score, and productive herd life using analysis of variance. Joint analysis of all families identified marker effects on 11 chromosomes that exceeded the genomewide, suggestive, or nominal significance threshold for QTL effects. Large marker effects on fat percentage were found on chromosomes 3 and 14, and multimarker regression analysis was used to refine the position of these QTL. Half-sibling families from Israeli Holstein dairy herds were used in a daughter design to confirm the presence of the QTL for fat percentage on chromosome 14. The QTL identified in this study may be useful for marker-assisted selection and for selection of a refined set of candidate genes affecting these traits.

Quantitative trait loci mapping in dairy cattle: review and meta-analysis

“…A genome-wide significant QTL for fat percent (FP) and FY with large effect was detected near the centromeric end of BTA14 using a GDD and confirmed with a DD in an independent population [31]. The same QTL has also been reported in many other studies [5,10,13,15,43,52,55,71].…”

“…On the same chromosome, a QTL for PY was detected at 46−70 cM in Norwegian cattle [49] and at 48 cM in DBDR families [53]. Ashwell et al [5], Boichard et al [10], Heyen et al [31] and Zhang et al [71] reported a QTL for PP towards the centromeric end of BTA3. Heyen et al [31] and Rodriguez-Zas et al [53] reported a QTL for PY on BTA3 near marker IL-STS96 (29.7 cM).…”

“…One such population of US Holstein Friesians is the Dairy Bull DNA Repository (DBDR), which has been extensively used for QTL detection [5,31,53]. Most of the DBDR sires were used in the 1980s and so this population may not be representative of the present population.…”

“…Ron et al [54] used a DD in the Israeli Holstein Friesian population for QTL mapping on BTA6 (Bos taurus autosome 6). Grisart et al [27] and Heyen et al [31] also used a DD as a part of their investigations of QTL on BTA14. More flexible designs are now being utilized, thanks to the development of suitable complex pedigree analysis methods [13].…”

“…Ashwell et al [5], Boichard et al [10], Heyen et al [31] and Zhang et al [71] reported a QTL for PP towards the centromeric end of BTA3. Heyen et al [31] and Rodriguez-Zas et al [53] reported a QTL for PY on BTA3 near marker IL-STS96 (29.7 cM). Mosig et al [47] employed selective DNA pooling in a DD and found 19−28 QTL affecting PP across the genome in the Israeli Holstein Friesian population.…”