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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

DOI: 10.1186/1746-6148-6-40

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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 SCD expression compared to other diets. In addition feeding system affected the fatty acid composition and SCD expression, possibly due to CLA concentration or the PUFA n-6/n-3 ratio. Both expression of the SCD gene and the feeding system were important factors affecting CLA concentration in the animal's semitendinous muscle. PPARγ, PPARα and SREBP1 expression seemed to be unaffected by the feeding system. Although no significant results were found, PPARγ, PPARα and SREBP1 showed similar expression pattern as SCD. Moreover, the correlation results between SCD expression and PPARγ (p < 0.01), as well as SREBP1 (p < 0.01) expression, may suggest that these genes were affecting SCD expression in a different way.The data indicated that the feeding system is the main factor affecting the fatty acid composition and SCD gene expression, which is also affected by CLA and possibly by n-6/n-3 PUFAs.Conjugated linoleic acids (CLAs) are a group of positional and geometric isomers of octadecadienoic acids with conjugated double bonds. These groups of fatty acids are receiving increasing attention because of their possible beneficial effects on human health; they reduce the incidence of atherosclerosis, diabetes and cancer in animals [1-8]. Milk and meat products derived from ruminants are important sources of CLA in the human diet [9]. The biohydrogenation of polyunsaturated fatty acids (PUFAs) that takes place in the rumen by microbial activity leads to an increase of saturated fatty acids (SFA), as well as their intermediate products. Some of the PUFAs and these intermediate products escape biohydrogenation and are incorporated into milk and body fat [10]. CLA is one of the most important intermediate products. The major isomer of CLA is cis-9, trans-11, which represents 80-90% of


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