Effect of the feeding system on the fatty acid composition, expression of the Δ⁹-desaturase, Peroxisome Proliferator-Activated Receptor Alpha, Gamma, and Sterol Regulatory Element Binding Protein 1 genes in the semitendinous muscle of light lambs of the Rasa Aragonesa breed

<p>Abstract</p> <p>Background</p> <p>Conjugated linoleic acids (CLAs) are receiving increasing attention because of their beneficial effects on human health, with milk and meat products derived from ruminants as important sources of CLA in the human diet. <it>SCD </it>gene is responsible for some of the variation in CLA concentration in adipose tissues, and <it>PPARγ</it>, <it>PPARα </it>and <it>SREBP1 </it>genes are regulator of <it>SCD </it>gene. The aim of this work was to evaluate the effect of the feeding system on fatty acid composition, CLA content and relative gene expression of Δ⁹-desaturase (<it>SCD</it>), Peroxisome Proliferator-Activated Receptor Gamma (<it>PPARγ</it>), Peroxisome Proliferator-Activated Receptor Alpha, <it>(PPARα) </it>and Sterol Regulatory Element Binding Protein <it>(SREBP1) </it>in Rasa Aragonesa light lambs in semitendinous muscle. Forty-four single-born male lambs were used to evaluate the effect of the feeding system, varying on an intensity gradient according to the use of concentrates: 1. grazing alfalfa, 2. grazing alfalfa with a supplement for lambs, 3. indoor lambs with grazing ewes and 4. drylot.</p> <p>Results</p> <p>Both grazing systems resulted in a higher concentration of vaccenic acid (VA), CLA, CLA/VA acid ratio, and a lower oleic content, oleic acid (C18:1)/stearic acid (C18:0) ratio, PUFA n-6/n-3 ratio and <it>SCD </it>expression compared to other diets. In addition feeding system affected the fatty acid composition and <it>SCD </it>expression, possibly due to CLA concentration or the PUFA n-6/n-3 ratio. Both expression of the <it>SCD </it>gene and the feeding system were important factors affecting CLA concentration in the animal's semitendinous muscle. <it>PPARγ, PPARα </it>and <it>SREBP1 </it>expression seemed to be unaffected by the feeding system. Although no significant results were found, <it>PPARγ, PPARα </it>and <it>SREBP1 </it>showed similar expression pattern as <it>SCD</it>. Moreover, the correlation results between <it>SCD </it>expression and <it>PPARγ </it>(p < 0.01), as well as <it>SREBP1 </it>(p < 0.01) expression, may suggest that these genes were affecting <it>SCD </it>expression in a different way.</p> <p>Conclusions</p> <p>The data indicated that the feeding system is the main factor affecting the fatty acid composition and <it>SCD </it>gene expression, which is also affected by CLA and possibly by n-6/n-3 PUFAs.</p>