Effect of hairless gene polymorphism on the breeding values of milk production traits in Valle del Belice dairy sheep

Abstract

The aim of this work was to assess the association between the hairless genotypes and estimated breeding values (EBVs) for milk yield (MY), fat (FAT) and protein (PRT) content in Valle del Belice dairy sheep breed. A data set from 465 randomly chosen unrelated individuals was analyzed. EBV for MY, FAT and PRT contents were estimated by REML analysis of a single trait repeatability animal model. The genotype effect on EBV was assessed by ANOVA and by the Tukey-Kramer multiple comparison test. The PCR-SSCP test showed the presence of CC and CT genotypes in Valle del Belice individuals. Some differences in milk production traits between the genotypes were found. For MY, individuals with CT genotype produced 1.5 times more daily milk than CC homozygotes. Individuals with CC genotype showed eight times less FAT content and 1.7 times less PRT content than the heterozygous. However, these differences were not statistically different, probably due to the low frequency of the CT genotype. Considering our results, polymorphisms of the hr gene do not directly influence production traits, but if further studies confirm our hypothesis, the hr gene could be used in a marker assisted selection program.

Determination of milk production losses and variations of fat and protein percentages according to different levels of somatic cell count in Valle del Belice dairy sheep

“…The means for MY, F% and P% were similar to those reported by Tolone et al (2013aTolone et al ( , 2013b while the mean SCC was higher than the value obtained by the same authors for the Valle del Belice sheep breed (Tolone et al, 2013b). Ewes lambed from August to November (SOL 1) produced more milk than those lambed from December to March (SOL 2) (−180 g/day) and from April to July (SOL 3) (−166 g/day).…”