Influence of organic systems on Stearoyl-CoA desaturase gene expression in goat milk

The effects of organic system on Stearoyl-CoA desaturase (SCD) gene expression in milk somatic cells was evaluated in 30 pregnant pluriparous goats, divided into two homogeneous groups (O and S). Group O was fed according to EC Regulation 834/2007 and led to pasture while group S was stabled and received alfalfa hay as forage. After kids weaning, milk yield was recorded and individual representative milk samples were analysed for chemical composition and fatty acid profile. The SCD gene expression was studied by extraction of mRNA from milk somatic cells and RT-PCR analysis. The body weight of goats of both groups did not show any significant change during the trial. Average milk yield did not differ statistically between the groups while milk from group O showed a significantly higher fat content than those from group S (65.9 vs. 54.3 g/day, P < 0.01). Organic system significantly affected the percentages of c9 C18:1, t11 C18:1, octadecadienoic acid, octadecatrienoic acid, monounsaturated fatty acids as well as the c9 t11 conjugated linoleic acid (CLA) (0.810 vs. 0.542 g/100 g of fat, for groups O and S, respectively, P < 0.01) and CLA (0.860 vs. 0.580 g/100 g of fat for groups O and S, respectively, P < 0.01) concentrations in milk. The Stearoyl-CoA desaturase ratios were not different between treatments. Finally, the SCD gene expression was significantly higher in the somatic cells in milk yielded from the “organic” group (AU:1.5±0.5 vs. 0.39±0.11 for groups O and S, respectively, P < 0.01).