Influence of oilseed supplementation on ruminant meat and milk with emphasis on fatty acidsTurner, Tyler;
In the human diet, long-chain polyunsaturated fatty acids (LC-PUFA, ≥ C20) are supplied almost exclusively from animal sources. Red meat represents a significant source of LC-PUFA in many areas of the world. However, the health aspects of consuming ruminant tissues are often viewed critically due to the proportions of saturated fatty acids (SFA). The health benefits from the monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) in ruminant muscle are often overlooked. Improvements to the lipid quality of ruminant tissues can be achieved through dietary manipulation. This thesis focuses on oilseed supplementation as a means to alter the FA profile of ruminant tissues. The results obtained indicate that the FA profile of the oilseed supplement and the feeding duration affected the muscle FA profile. The diet and nutritional status of the lactating ewes affected the milk FA profile, in turn affecting the growth performance and M. semispinalis capitis FA profile of the lambs after weaning. Modifying the FA profile of ruminant meat requires reducing the accessibility of dietary PUFA to ruminal biohydrogenation. Heat processing has been shown to alter the oilseed protein structure, increasing the post-ruminal supply of amino acids and PUFA. Roasting and extruding were equally effective processes for increasing the in vitro undegradable N fraction of linseed and soybean without affecting N digestibility. The M. masseter and M. pars costalis diaphragmatis, collected from animals fed roasted or extruded oilseeds had PUFA profiles which were influenced both by the dietary n-6/n-3 PUFA ratio and by the Δ5- (Δ5d) and Δ6- (Δ6d) desaturase enzymes responsible for forming LC-PUFA. Moreover, the Δ5d and Δ6d protein expressions were correlated within the muscles, whereas the dietary regulation of the Δ5d and Δ6d protein expression was muscle specific. Based on these findings, dietary oilseed supplementation modified the FA profile of ruminant products, improving the health benefits from their consumption. Further studies into oilseed processing and influence of diet on the lipogenic pathways will assist in feeding strategies to further enhance the health benefits from ruminant meat consumption.
fatty acids; lipids; proximate composition; ruminants; feeds; oilseeds; supplementary feeding; milk; meat; nutritive value
Published inActa Universitatis Agriculturae Sueciae 2010, number: 2010:54
Publisher: Dept. of Food Science, Swedish University of Agricultural Sciences
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