Abstract: The effect of different feeding systems on fatty acid composition and lipid metabolism-related gene expression in Biceps femoris from Sunit sheep was investigated. A total of 20 twelve-month-old sheep were allocated to two feeding regimens with 10 animals each (half each gender): grazing and stall feeding. Fatty acid composition was determined by gas chromatography-mass spectrometry. The expression of fatty acid synthase (FASN), sterol regulatory element binding protein1-c (SREBP1-c), diacylglycerol acyltransferase (DGAT), peroxisome proliferators-activated receptors γ (PPARγ), hormone sensitive lipase (HSL), lipoprotein lipase (LPL), fatty acid dehydrogenase 1 (FADS1) and fatty acid dehydrogenase 2 (FADS2) genes was evaluated by real-time quantitative polymerase chain reaction. The results showed that meat from grazing sheep had significantly lower amounts of saturated fatty acids than stall-fed sheep (P < 0.05). The contents of palmioleic acid and oleic acid as monounsaturated fatty acids and the contents of α-linolenic acid, conjugated linoleic acid, eicosapentaenoic acid and docosahexaenoic acid as unsaturated fatty acids were significantly higher than in the stall-fed group (P < 0.05). The expression of SREBP1-c gene was significantly lower in the grazing group (P < 0.05) whereas the expression of DGAT, HSL, and FADS2 genes were significantly higher compared with the stall-fed group (P < 0.05). The expression of PPARγ gene and saturated fatty acid content had a significantly negative correlation with each other (P < 0.05). Thus, in terms of fatty acid composition, meat from grazing animals had a higher nutritional value. Furthermore, the nutritional quality of meat from stall-fed sheep could be improved by regulating the expression of fatty acid metabolism-related genes.

Key words: feeding regimens, Sunit sheep, fatty acid composition, gene expression