Volume 88, Issue 1, July (2002), pp. 11-18 © The Author 2002

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

Ronald E. Newman^1,4*, Wayne L. Bryden^1,4, Eva Fleck², John R. Ashes², William A. Buttemer³, Leonard H. Storlien^3,4 and Jeffery A. Downing^1,4
1Faculty of Veterinary Science, University of Sydney, Camden, NSW, Australia
²CSIRO Livestock Industries, Prospect, NSW, Australia
³Departments of Biological and Biomedical Sciences, University of Wollongong, NSW, Australia
⁴Smart Food Centre, University of Wollongong, NSW, Australia

 (Received 30 August 2001–Revised 11 January 2002–Accepted 3 February 2002)

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.