Depresión de la grasa láctea en ovejas que consumen lípidos de origen marino: 2 ¿Puede la abundancia de arnm de genes implicados en la lipogénesis mamaria explicar la variación individual?

Abstract

This study was conducted in dairy sheep to test the hypothesis that differences in the transcriptional regulation of mammary lipogenesis may be responsible for individual variations in terms of milk fat depression (MFD) in response to diet supplementation with marine lipids. Fifteen ewes receiving a total mixed ration supplemented with 0 (control; n=5) or 20 g of fish-oil/kg DM [n=10; with animals divided in those showing a strong (RESPO+, n=5) or slight (RESPO-) MFD] were used. Candidate gene expression was analysed by quantitative reverse transcription-PCR on milk somatic cells collected on days -2 or -1 and 34 or 35. Consumption of the fish oil diet tended to reduce the mRNA abundance of ACSS2, FASN, LPIN1 and INSIG1 (P<0.10), but only SCD and GPAT4 showed a tendency to differ between RESPO+ and RESPO- ewes (P<0.10). These results would support that the nutritional regulation of milk synthesis is mediated by transcriptional mechanisms but oblige to reject the initial hypothesis.