Effects of concentrate supplementation on fatty acid composition and expression of lipogenic genes of meat and adipose tissues in grazing lambs

Effects of natural grazing (NG) or grazing with supplementary feeding (GS) of Hulunbeier lambs (HL) and Hulunbeier × Dorper crossbred lambs (HZ) on fatty acid (FA) profile and lipogenic gene expressions in the longissimus thoracis (LT) and subcutaneous adipose tissue (SAT) were determined. The study was conducted as a 2 × 2 factorial arrangement using four-month old lambs. Thirty animals were divided into each group. The FA composition and the expression of lipid metabolism gene of sheep were affected by the feeding regimens and animal breeds. Compared with NG, GS increases de novo FA synthesis of LT and SAT, which decreases GS lambs’ FA nutrition value. Meat or fat from NG lambs present more n-3 long-chain polyunsaturated FA that is beneficial to human health. Under the two feeding regimens, de novo synthesis of FA and fat deposition seems to higher in HZ lambs compared with those in HL as the expression of genes (SREBP1c, FAS, ACC, C/EBPα, PPARγ) that are associated with correlative metabolism was increased in HZ lambs. Meat from HZ lambs displays a less favourable level of saturated FA as containing higher content of C14:0, but it also presents higher profile of EPA than HL lambs.Highlights Feeding ways and breeds affect fatty acids and gene. Meat from grazing lambs is beneficial to human health. Supplementary feeding increases fat deposition