Dietary n-3 and n-6 fatty acids alter avian metabolism: metabolism and abdominal fat deposition.

The effects of dietary saturated fatty acids and polyunsaturated fatty acids (PUFA) of the n-3 and n-6 series on weight gain, body composition and substrate oxidation were investigated in broiler chickens. At 3 weeks of age three groups of chickens (n 30; ten birds per group) were fed the fat-enriched experimental diets for 5 weeks. These diets were isonitrogenous, isoenergetic and contained 208 g protein/kg and 80 g edible tallow, fish oil or sunflower oil/kg; the dietary fatty acid profiles were thus dominated by saturated fatty acids, n-3 PUFA or n-6 PUFA respectively. Resting RQ was measured in five birds from each treatment group during weeks 4 and 5 of the experiment. There were no significant differences between treatments in total feed intake or final body mass. Birds fed the PUFA diets had lower RQ and significantly reduced abdominal fat pad weights (P<0.01) compared with those fed tallow. The dietary lipid profile changes resulted in significantly greater partitioning of energy into lean tissue than into fat tissue (calculated as breast lean tissue weight:abdominal fat mass) in the PUFA groups compared with the saturated fat group (P<0.01; with no difference between the n-3 and n-6 PUFA groups). In addition, the PUFA-rich diets lowered plasma concentrations of serum triacylglycerols and cholesterol. The findings indicate that dietary fatty acid profile influences nutrient partitioning in broiler chickens.

Dietary n-3 and n-6 fatty acids alter avian metabolism: molecular-species composition of breast-muscle phospholipids.

The effects of diets high in n-3 polyunsaturated fatty acids (PUFA; provided by fish oil), n-6 PUFA (sunflower oil) or in more-saturated fatty acids (tallow) on the distribution of subclasses of choline phospholipids (PC) and ethanolamine phospholipids (PE) from the breast muscle of broiler chickens were examined. Supplementation with the different fatty acids had no effect on the distribution of phospholipid subclasses. Feeding sunflower oil or tallow gave a molecular-species profile similar in both fatty acid subtype and proportion. In the diacyl PC phospholipids, 16 : 0-18 : 1n-9 and 16 : 0-18 : 2n-6 accounted for approximately 60 % of the total molecular species, whereas for the alkylenyl PC the predominant species were 16 : 0-18 : 1n-9 and 16 : 0-20 : 4n-6. Of the diacyl PE the dominant species was 18 : 0-20 : 4n-6 which accounted for 50 % of the molecular species, and of the alkylenyl PE the dominant species were 16 : 0-18 : 1n-9, 16 : 0-20 : 4n-6 and 18 : 0-20 : 4n-6. Supplementation with fish oil significantly increased levels of both eicosapentaenoic acid (20 : 5n-3) and docosahexaenoic acid (22 : 6n-3) in PC and PE when compared with either sunflower oil or tallow supplementation. The increase in the n-3 PUFA incorporation was associated with a corresponding decrease in the proportion of arachidonic acid (20 : 4n-6) in both PC and PE. Different dietary fats induce different patterns of fatty acid incorporation and substitution in the sn-2 position of the diacyl and alkylenyl PC and PE of avian breast muscle, and this finding is indicative of selective acyl remodelling in these two phospholipids.