Effect of Feeding and Withdrawal of Menhaden Oil on the w3 and w6 Fatty Acid Content of Broiler Tissues

SUMMARY– Analysis was made of the fatty acid composition of liver, adipose fat, thigh and breast muscles of broilers fed corn-soy commercial-type of diets containing one of two levels of fish oil (2.5 or 5.0%). The oil was subsequently continued, withdrawn or replaced with yellow grease 2, 3 or 4 weeks before termination of the experiment at the 8th week. The tissue contents of four w-3-type fatty acids (20:4, 20:5, 22:5 and 22:6) were increased in relation to the number of weeks menhaden fish oil was included in the diet. (The first number indicates the chain length of carbons, the second indicates the number of double bonds. The number following w (omega) indicates the carbon position of the first double bond as counted from the terminal methyl group.) Of the four tissues studied, the liver had the highest total content of the w3 fatty acids; the adipose fat, the least. The muscles had intermediate values; the breast containing more than the thigh. Withdrawal of fish oil at the 4th week resulted in favorable organoleptic evaluation. A more favorable evaluation was obtained if yellow grease was substituted in place of fish oil for the last 4 weeks. The organoleptic scores were highly significantly correlated with the content of 20:5 03, 22:5 w3 and 22:6 w3 but it was less significantly correlated with the content of 20:4 w3. An inverse relation existed between the content of the w3 with that of the w6 fatty acids.