Nutritional effects of autoxidized fats in animal diets

Abstract

1. In two experiments, 100 pigs were fed from age 4 or 5 weeks to age 16–19 weeks on practical-type diets containing 10% of meat meal (15–17% lipid) of either low (3–17) or high (114–150 μmoles/g lipid) peroxide value. The cereal basis of the diet in the first experiment was wheat and maize and in the second barley. Other variants were the inclusion of a stabilized vitamin E supplement in the diet of one of the groups in Expt 1, the presence of 100 (Expt1) or 250(Expt 2)ppm of copper, and storage of a diet containing oxidized meat meal for 6–21 weeks before feeding to one of the groups in Expt 2.2. Apart from an unusually high incidence of stomach ulcers which, however, were almost equally distributed between the control and oxidized fat groups and did not appear to affect the health and nutrition of the animals, the pigs grew well, with no significant difference between the groups in weight gain, food conversion ratio, liver weight, vitamin A storage in the liver, and aspartate aminotransferase and alanine aminotransferase activities in the serum.3. Changes in the lipids of the diets during storage were studied and samples of back fat from the carcasses examined for fatty acid composition, tocopherol content and susceptibility to autoxidation. Moisture content appeared to be a major factor influencing the oxidative stability of the meat meals used. Tocopherol content and oxidative stability of the pig fat were highest in the group given a vitamin E supplement, and generally lower in Expt 2 than in Expt 1.