Influence of Dietary Fat Source and Vitamin E on Market Stability of Turkeys

Wrolstad Small White turkeys were fed corn-soybean diets containing no added dietary fat, 8% hydrolyzed animal-vegetable fat, 8% animal fat, or 8% soybean oil. Within each fat source, diets were varied with respect to vitamin E content so that unsupplemented, 10 IU/kg (usual) and 300 IU/kg resulted. Birds were maintained on these diets until they were sacrificed at 14 weeks of age. All fats resulted in comparable improvement in feed efficiency. At the end of the growing period the carcasses were divided in half with one half held at 3 C for 3 weeks while the other half was frozen and held 6 months at −20 C. Animal fat or animal-vegetable fat resulted in elevated muscle thiobarbituric acid (TBA) values over those produced in corn-soybean meal diet following 3 weeks of refrigeration. The usual vitamin E level added a small degree of protection in terms of stability, while the high level of vitamin E resulted in substantial protection against onset of oxidative rancidity. Frozen carcasses were subjected to similar TBA analyses; in no case was there any significant build up of TBA reactive substances in the tissues. Following frozen storage, samples of meat were cooked, held 48 hr at 4 C, and then subjected to TBA analysis. These samples showed significant build up at TBA reactive substances which had virtually no relationship to source of dietary fat. High levels of vitamin E offered some protection against the “warmed-over” type of rancidity.