Abdominal fat deposition and fatty acid synthesis are lower and beta-oxidation is higher in broiler chickens fed diets containing unsaturated rather than saturated fat.

We evaluated the effects of dietary fat type on fat metabolism and deposition in broiler chickens. Birds were fed diets containing either 8 g dietary saturated (beef tallow) or polyunsaturated fat (sunflower oil)/100 g for 32 d. The abdominal fat deposition of chickens fed the sunflower oil-enriched diet was significantly lower than that of chickens fed the tallow-enriched diet (2.63 +/- 0.47 versus 3.03 +/- 0.44 g/100 g live wt.; P = 0.033). The specific activities of heart carnitine palmitoyltransferase I and L-3-hydroxyacyl-CoA dehydrogenase were higher (P < or = 0.03) in chickens fed the sunflower oil-enriched diets, indicating a greater rate of beta-oxidation. Liver fatty acid synthetase activity was lower (P = 0.01) in chickens fed the sunflower oil-enriched diet, suggesting reduced hepatic lipogenesis in this group. Postprandial plasma triglyceride levels were significantly lower (P < 0.05) in birds fed the sunflower oil-enriched diet, indicating a higher rate of dietary lipid clearance from the bloodstream to tissues. In conclusion, the lower fat deposition observed in broilers fed sunflower oil-enriched diets appears to be the net result of an increased rate of lipid catabolism and lower rate of fatty acid synthesis despite higher dietary fat absorption.