Effects of feeding regimens on meat quality, fatty acid composition and metabolism as related to gene expression in Chinese Sunit sheep

Abstract

The present study investigated the effects of two feeding regimens on meat quality, fatty acid profile and metabolism as it relates to gene expression in Sunit sheep. Two feeding regimens were used (pasture feeding and barn feeding, PF and BF) each containing 10 Sunit sheep. Results of this study indicated that PF sheep had significantly (P < 0.05) higher L* and b* values in their muscle compared to BF sheep. Also, the fatty acid composition of longissimus dorsi muscle and subcutaneous adipose tissues differed between feeding regimens. In this respect, concentrations of palmitic acid (C16:0) in the subcutaneous adipose tissue were significantly (P < 0.05) higher in BF sheep. Pastured sheep exhibited greater concentrations of polyunsaturated fatty acids (PUFA) including: linolenic acid (C18:3) (P < 0.001), DHA (P < 0.05), EPA (P < 0.001) and CLA cis-9, trans-11(P < 0.05) in their muscle compared to BF sheep. The expression of nine candidate genes related to fatty acid metabolism were analyzed by qPCR. In longissimus dorsi muscle, expression of acetyl CoA carboxylase (ACACA; P < 0.05) was up-regulated in BF sheep. Expression of the peroxisome proliferator activated receptor (PPARγ) (P < 0.05), stearoyl CoA desaturase (SCD) (P < 0.01), fatty acid desaturase1 (FADS1) (P < 0.05) and fatty acid desaturase 2 (FADS2) (P < 0.05) were up-regulated in PF sheep. Pasture feeding also increased (P < 0.05) expression of lipoprotein lipase (LPL), PPARγ, SCD, FADS1and fatty acid elongase 5 (Elove5) in the subcutaneous adipose tissue, however, the feeding regimens did not change expression of fatty acid synthase (FASN) and carnitine palmitoyl transferase I (CPT1). The results of this study indicated that the feeding regimen could be an important tool in manipulating the fatty acid profile of animal adipose tissue by altering the gene expression of enzymes involved in fat metabolism.