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 oxidative stability of the thigh muscle of turkeys stored at -18 C for various periods. Iron was added to a commercial diet that already contained 20 mg/kg supplemental Fe, at concentrations of 0, 100, 250, and 500 mg/kg as ferrous sulfate or injected as Fe-dextran to the left drumstick muscle (total amount of 1.2 g per turkey). Vitamin E was added to the experimental diets not already supplemented with this vitamin, at levels 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 supplementation from 0 to 500 mg/kg tended to decrease TEARS values in one experiment only; otherwise, this variable was not affected by dietary Fe level. Injection of Fe significantly (P < 0.05) increased TEARS values, only in meat from the injected side. The TEARS values of the meat up to about 30 d of storage were significantly lower due to the supplementation of the diet with vitamin E at a level of 28 mg/kg in one out of three experiments and at a level of 150 mg/kg in two out of two experiments. The protective effect of the higher level of vitamin E remained evident after about 108 d of storage. No interaction was observed between Fe and vitamin E treatments in their effect on TEARS values. Blood hemoglobin concentrations were significantly increased by the supplementation 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 do 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.