Effect of diet, sex and age on fatty acid metabolism in broiler chickens: n-3 and n-6 PUFA.

The PUFA metabolism in broiler chicken was studied through the whole body fatty acid balance method. Four dietary lipid sources (palm fat, Palm; soyabean oil, Soya; linseed oil, Lin; fish oil, Fish) were added at 3 % to a basal diet containing 5 % palm fat. Diets were fed to female and male birds from day 1 to either day 21 or day 42 of age. Birds fed the Lin diet showed a significantly higher 18 : 2n-6 accumulation compared with the other diets (85.2 v. 73.6 % of net intake), whereas diet did not affect 18 : 3n-3 accumulation (mean 63 % of net intake). Bioconversion of 18 : 2n-6 significantly decreased in the order Palm>Lin>Soya>Fish (4.7, 3.9, 3.4 and 1 % of net intake, respectively). The 18 : 3n-3 bioconversion on the Palm and Soya diets was similar and significantly higher than in broilers on the Lin diet (9.1 v. 5.8 % of net intake). The beta-oxidation of 18 : 2n-6 was significantly lower on the Lin diet than on the other diets (10.8 v. 23.3 % of net intake), whereas beta-oxidation of 18 : 3n-3 was significantly higher on the Fish diet than on the other diets (41.5 v. 27.3 % of net intake). Feeding fish oil suppressed apparent elongase and desaturase activity, whereas a higher dietary supply of 18 : 3n-3 and 18 : 2n-6 enhanced apparent elongation and desaturation activity on the PUFA involved in the n-3 and n-6 pathway, respectively. Accumulation of 18 : 2n-6 and 18 : 3n-3 increased and beta-oxidation decreased with age. Sex had a marginal effect on the PUFA metabolism.