EFFECT OF HIGH-LEVELS OF DIETARY IRON, IRON INJECTION, AND DIETARY VITAMIN-E ON THE OXIDATIVE STABILITY OF TURKEY MEAT DURING STORAGE

A study was carried out to evaluate the combined effect of excess Fe, supplied either in the diets (Experiments 1, 2, and 3) or by injection (Experiment 4), and various levels of dietary vitamin E on the oxidat ive stability of the thigh muscle of turkeys stored at -18 C for vario us periods. Iron was added to a commercial diet that already contained 20 mg/kg supplemental Fe, at concentrations of 0, 100, 250, and 500 m g/kg as ferrous sulfate or injected as Fe-dextran to the left drumstic k muscle (total amount of 1.2 g per turkey). Vitamin E was added to th e experimental diets not already supplemented with this vitamin, at le vels of 0, 28, and 150 mg/kg. Thiobarbituric acid reactive substances (TEARS) values of the meat gradually increased as its storage duration increased from about 15 to 120 d. Increasing dietary Fe supplementati on from 0 to 500 mg/kg tended to decrease TEARS values in one experime nt only; otherwise, this variable was not affected by dietary Fe level . Injection of Fe significantly (P < 0.05) increased TEARS values, onl y in meat from the injected side. The TEARS values of the meat up to a bout 30 d of storage were significantly lower due to the supplementati on of the diet with vitamin E at a level of 28 mg/kg in one out of thr ee experiments and at a level of 150 mg/kg in two out of two experimen ts. The protective effect of the higher level of vitamin E remained ev ident after about 108 d of storage. No interaction was observed betwee n Fe and vitamin E treatments in their effect on TEARS values. Blood h emoglobin concentrations were significantly increased by the supplemen tation of the diet with the high levels of Fe, in one experiment only. This variable was consistently and significantly increased from about 10 to 23 wk of age. The results show that high levels of dietary Fe d o not adversely affect the oxidative stability of thigh meat of turkey ; however, stability might be reduced by injected Fe. Dietary vitamin E, at a level of 150 mg/kg, consistently increased this stability.