Association Analysis between SPP1, POFUT1 and PRLR Gene Variation and Milk Yield, Composition and Coagulation Traits in Sarda Sheep

SIMPLE SUMMARY: The purpose of our research was to analyze the association between the three candidate genes secreted phosphoprotein 1 (SPP1), protein O-fucosyltransferase 1 (POFUT1) and prolactin receptor (PRLR) with milk production, quality and coagulation properties in 380 Sarda dairy sheep. Results revealed an association between SPP1 and somatic cells count, in line with the function of this gene and with its genomic position. We revealed an association of POFUT1 variation with milk coagulation properties, and PRLR with quality. This information can be useful for future breeding schemes in sheep. ABSTRACT: Many studies focus on the identification of genomic regions that undergo selective processes, where evidence of selection is revealed and positional candidate genes are identified. The aim of the research was to evaluate the association between positional candidate genes, namely secreted phosphoprotein 1 (SPP1, sheep chromosome Ovis aries OAR6, 36.651–36.658 Mb), protein O-fucosyltransferase 1 (POFUT1, OAR13, 61.006–61.027 Mb) and prolactin receptor (PRLR, OAR16, 38.969–39.028 Mb) with milk yield, composition and coagulation traits. Eight single nucleotide polymorphisms (SNPs) mapping to the three genes were genotyped in 380 Sarda dairy sheep. Statistical analysis revealed an association between SNP rs161844011 at SPP1 (chromosome position Oar_v3 OAR6:36651870, gene region exon 7) and somatic cell score, while POFUT1 SNP rs424501869 (OAR13:61007495, intron 1) was associated with curd firmness both 45 and 60 min after rennet addition (p = 0.015 and p = 0.007, respectively). SNP rs400874750 at PRLR gene (OAR16:39004070, intron 2) had a significant association with lactose content (p = 0.020), somatic cell score (p = 0.038), rennet coagulation time (p = 0.018) and curd firming time (p = 0.047). The outcome of this research confirmed predictions based on genomic studies, producing new information regarding the SPP1, POFUT1 and PRLR genes, which may be useful for future breeding schemes.