Quantitative Trait Loci Affecting Fertility and Calving Traits in Swedish Dairy Cattle

Abstract

Impaired fertility is the main reason for involuntary culling of dairy cows in Sweden. The objective of this study was to map quantitative trait loci (QTL) influencing fertility and calving traits in the Swedish dairy cattle population. The traits analyzed were number of inseminations, 56-d nonreturn rate, interval from calving to first insemination, fertility treatments, heat intensity score, stillbirth, and calving performance. A genome scan covering 20 bovine chromosomes was performed using 145 microsatellite markers. The mapping population consisted of 10 sires and their 417 sons in a granddaughter design. Nine of the sires were of the Swedish Red Breed, and one was a Swedish Holstein. Least squares regression was used to map loci affecting the analyzed traits, and permutation tests were used to set significance thresholds. Cofactors were used in the analyses of individual chromosomes to adjust for QTL found on other chromosomes. The use of cofactors increased both the number of QTL found and the significance level. In the initial analysis, we found 13 suggestive QTL that were mapped to chromosomes 6, 7, 9, 11, 13, 15, 20, and 29. When cofactors were included, 30 QTL were detected on chromosomes 1, 3, 4, 18, 19, 22, and 25, in addition to the 8 previously mentioned chromosomes. Some of the results from the cofactor analysis may be false positives and require further validation. In conclusion, we were able to map several QTL affecting fertility and calving traits in Swedish dairy cattle.

Genome-wide associations for fertility traits in Holstein–Friesian dairy cows using data from experimental research herds in four European countries

“…Although not all studies have documented significant associations with different measures of reproductive performance on either BTA 2 or BTA 21 (Holmberg and Andersson-Eklund, 2006;Pryce et al, 2010), significant associations with SNPs on BTA 2 and BTA 21 have been reported in some studies (Huang et al, 2010;Sahana et al, 2010;Schulman et al, 2011). Of particular note were the two SNPs, ARS-BFGL-NGS-36151 and BTB-00117780, reported by Huang et al (2010) on BTA 2 to be associated with fertilisation rate in a Holstein population independent to that used in the present study.…”

“…Several other studies have attempted to locate genomic regions associated with reproductive performance in cattle (Holmberg and Andersson-Eklund, 2006;Huang et al, 2010;Pryce et al, 2010;Sahana et al, 2010;Schulman et al, 2011). Although not all studies have documented significant associations with different measures of reproductive performance on either BTA 2 or BTA 21 (Holmberg and Andersson-Eklund, 2006;Pryce et al, 2010), significant associations with SNPs on BTA 2 and BTA 21 have been reported in some studies (Huang et al, 2010;Sahana et al, 2010;Schulman et al, 2011).…”

“…Most studies to date that attempted to identify quantitative trait loci (QTLs) in dairy cattle have used specific study designs such as (grand-) daughter designs (Weller et al, 1990;Holmberg and Andersson-Eklund, 2006;Hö glund et al, 2009), and have therefore been generally limited to routinely available phenotypes. We are not aware of any genome-wide association study for traditional measures of fertility in dairy cattle that has been undertaken using actual cow phenotypic data.…”

Mouse models for identifying genes modulating fertility parameters

“…Several recent studies taking into account fertility parameters alongside other production traits illustrate this point (Kirkpatrick et al, 2000;Lien et al, 2000;Boichard et al, 2003;Ashwell et al, 2004;Schnabel et al, 2005). To the best of our knowledge, only four studies in cattle focused exclusively on fertility traits (Holmberg and Andersson-Eklund, 2006;Guillaume et al, 2007;Holmberg et al, 2007;Schulman et al, 2008), while the other studies involve the phenotyping of other production traits. Loci involved mainly in female fertility were identified (see Table 1).…”

Quantitative trait loci for fertility traits in Finnish Ayrshire cattle

“…Calf mortality (stillbirth) as a maternal trait has been previously mapped by Holmberg and Andersson-Eklund [15] and Kühn et al [24]. QTL were suggested on BTA4 and 19 and detected at genome-wise significance on BTA7 and 11 [15] and BTA8, 10, 18, and X/Y [24].…”