An association analysis between OXT genotype and milk yield and flow in Italian Mediterranean river buffalo

The aim of this study was to evaluate possible associations between three SNPs at the oxytocin locus(AM234538: g.28C>T; g.204A>G and g.1627G>T) and two productive traits, milk yield andmilkability, in Italian Mediterranean river buffaloes. Effects of parity, calving season and monthof production were also evaluated. A total of 41980 test-day records belonging to 219 lactations of163 buffalo cows were investigated. The allele call rate was 98·8%and the major allele frequency forall the investigated loci was 0·76. The OXT genotype was significantly associated with milk yield(P=0·029). The TT genotype showed an average daily milk yield approximately 1·7 kg higher thanGT buffaloes. Such a difference represents about 23% more milk/d. A large dominance effect(1·17±0·43 kg) was estimated, whereas the contribution of OXT genotype (r2OXT) to the totalphenotypic variance in milk yield was equal to 0·06. The TT genotype showed higher values also forthe milk flow, even though the estimated difference did not reach a level of statistical significance(P=0·07). Such an association, among the first reported for the oxytocin locus in ruminants, should betested on a population scale and possible effects on milk composition traits should be evaluated inorder to supply useful indications for the application of marker-assisted selection programmes in riverbuffaloes.