Abstract

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 and milkability, in Italian Mediterranean river buffaloes. Effects of parity, calving season and month of production were also evaluated. A total of 41980 test-day records belonging to 219 lactations of 163 buffalo cows were investigated. The allele call rate was 98·8%and the major allele frequency for all 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 than GT 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 (r² _OXT) to the total phenotypic variance in milk yield was equal to 0·06. The TT genotype showed higher values also for the 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 be tested on a population scale and possible effects on milk composition traits should be evaluated in order to supply useful indications for the application of marker-assisted selection programmes in river buffaloes.

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