Effects of dietary fish oil on the composition and stability of turkey depot fat

Abstract

1. Beef fat (2.5%) and anchovy oil (2.5%; 2.5% plus 0.02% ethoxyquin; 5%) were incorporated into isocaloric cereal-based diets A, B, C and D and given to turkeys from 2 to 10 weeks of age. Diets A, B, and C contained 13 and diet D 26 i.u. α-tocopheryl acetate/kg. The lipids of diets B and D, which contained fish oil without ethoxyquin, autoxidized in the feeding troughs, but not seriously in the brief period of exposure permitted. 2. The birds all remained healthy and grew well, the only nutritional effects of the fish oil being a depressed storage of vitamin A in the liver at both levels of feeding (prevented by ethoxyquin) and a slightly adverse effect, at the higher level only, on food conversion ratio. 3. The skin fats of the birds given fish oil contained seven major and two minor fatty acids, derived from the fish oil, which were not present in the skin of the control group given beef fat, as well as one major fish oil acid present in much greater concentration in the birds given fish oil than in the controls. All these acids were present in the skin fats at about half or two-thirds of their concentrations in the dietary lipid, except for acid 22:5, which reached two or three times this level. 4. The stabilities towards autoxidation of the skin fats decreased in the order A > C > B > D, as their content of polyunsaturated fatty acids increased, but the greater stability of group C as compared with B was probably due, in the main, to the higher tocopherol content of the skin fat of the birds on the ethoxyquin-containing diet. Fishy flavours which developed on cooking showed a similar relationship to diet.