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 β-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), whereasβ-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 andβ -oxidation decreased with age. Sex had a marginal effect on the PUFA metabolism.