The objective of this study was to assess the oxidative stability and presence of antibiotic residues in tissues of broilers fed diets supplemented with alpha-tocopheryl acetate and treated with enrofloxacin. The activities of antioxidant enzymes and antibiotic concentrations in chicken breast, leg, and liver were determined. Iron-induced TBA-reactive substances (TBARS) and vitamin E were evaluated in muscles. The antioxidant effectiveness of vitamin E was reflected by TBARS values being lower in antioxidant-supplemented treatments than in the other dietary groups. On the other hand, antioxidant enzyme activities were not substantially affected by dietary treatments. The concentration of enrofloxacin in tissues was considerable, even after withdrawal 12 d before slaughter. Contrary to the findings in previous studies, enrofloxacin was not extensively metabolized to ciprofloxacin. Supplementation of the diet with 100 mg/kg of alpha-tocopheryl acetate did not have a significant effect on the level of antibiotic found in breast muscle samples. When comparing treatments without antibiotic withdrawal time, alpha-tocopheryl acetate supplementation led to a significant decrease in enrofloxacin level in leg and liver samples. These results showed that mutual interactions between different molecules could modify the drug residues in the tissue, which should be taken into account when considering the drug administration and the establishment of a correct withdrawal time.

The objective of this study was to investigate the effect of dietary α-tocopheryl acetate and β-carotene supplementation on lipid oxidation of breast meat from broilers fed lard as the fat source. Supplementation of broilers with 100 mg kg −1 α-tocopheryl acetate increased the vitamin E levels in raw breast samples significantly (p < 0.05), whereas the presence of 1.5 mg kg −1 dietary β-carotene tended to decrease vitamin E deposition. The presence of vitamin E delayed lipid oxidation significantly, but thiobarbituric acid values of samples from broilers fed the β-carotene-supplemented diet did not differ from those of control samples. Vitamin E reduced sensory meat rancidity, whilst vitamin E, β-carotene and their combination modified meat texture. The results show the effectiveness of dietary α-tocopheryl acetate supplementation in protecting broiler meat against lipid oxidation.

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1. The aim of the study was to evaluate the effects of alpha-tocopheryl acetate (50 mg/kg) and beta-carotene (15 mg/kg) dietary supplementation on the oxidative status of raw turkey breast and leg muscles assessed by thiobarbituric acid test values, the vitamin E levels and the antioxidant enzyme activities. In parallel, a quantitative descriptive sensory analysis was carried out on cooked, stored and reheated samples. 2. Vitamin E was present in sufficient quantity to reduce oxidation, since iron-induced reactive substances (TBARS) were significantly lower in antioxidant-supplemented treatments. The results suggested that the presence of beta-carotene in the diet limits the accumulation of alpha-tocopherol in turkey muscles. 3. In the present study, there was no conclusive relationship between dietary antioxidant supplementation and endogenous antioxidant enzyme activities. 4. Sensory evaluation showed that a longer supplementation time and dose may be necessary in turkeys to prevent meat from rancidity and warmed-over flavour (WOF). Leg pastiness and stringiness were modified by dietary antioxidant supplementation, indicating the possible synergism between antioxidants and cysteine proteinases in the perception of meat quality. 5. Given the modern trends that lead consumers to increase their consumption of poultry meat, it would be interesting to evaluate the commercial potential and cost effectiveness of routine dietary antioxidant supplementation.

The objective of this study was to assess the effect of enrofloxacin administration with and without withdrawal period on the quality of fresh meat and cooked products from turkey breasts. Cathepsin B and L activities were inactivated by the thermal process but were not affected by the presence of enrofloxacin. The level of enrofloxacin in samples without withdrawal time was higher than the regulatory maximum residue limit (MRL). The antioxidant enzymes glutathione peroxidase (GSHPx) and catalase (CAT) were affected by both the thermal process and the antibiotic residues in cooked meat. In no cases were differences found in superoxide dismutase (SOD) activity, supporting the theory that this enzyme could play a major role in preventing lipid oxidation of cooked meat. Enrofloxacin residues could contribute to an increase in the oxidative stress produced by thermal processing, as can be deduced by the reduction in GSHPx and CAT activities.