Effect of trans-10, cis-12 conjugated linoleic acid (CLA) on expression of lipogenic genes is related to amount of trans-10, cis-12 CLA per unit of metabolic weight in lactating dairy ewes

This study evaluated the effect of trans-10, cis-12 CLA on the expression of genes involved in decreasing milk fat synthesis in two groups of lactating ewes with different metabolic weights. Twelve Lacaune ewes were alloted, according to metabolic weight (MW), into a Light Metabolic Weight (LMW) and Heavy Metabolic Weigth (HMW) groups, both of which were orally fed 30 g/d of rumen-unprotected CLA supplement containing 29.9% trans-10, cis-12. Milk samples were collected on days 0, 3 and 10 and mammary and adipose tissue biopsies were taken on days 3 and 10. RNA extraction, cDNA synthesis and RT-qPCR were performed and data were analyzed using the MIXED procedure of SAS as repeated measure in a completely randomized design. The trans-10, cis-12 CLA reduced milk fat synthesis between days 3 and 10 (P = 0.001), and the HMW group had a greater expression (P < 0.05) of the genes acetyl-CoA carboxylase alpha - promoter III (ACACA-alpha PIII), fatty acid synthase (FASN), stearoil CoA desaturase 1 (SCD1) and thyroid hormone responsive spotl4 (THRSP) in the mammary gland and of acetyl-CoA carboxylase alpha - promoter I (ACACA-alpha PI) and leptin (P < 0.05) in adipose tissue. Our findings indicate that the response of animals to trans-10, cis-12 CLA appears to be metabolic weight dependent.