Effect of vitamin E level and dietary zinc source on performance and intestinal health parameters in male broilers exposed to a temperature challenge in the finisher period

The objective of this study was to evaluate the interaction of zinc source (ZnSO4 vs. zinc amino acid complex) and vitamin E level (50 IU vs. 100 IU) on performance and intestinal health of broilers exposed to a temperature challenge in the finisher period. A total of 1224 day old male Ross 308 broilers were randomly distributed among 4 dietary treatments (9 replicates per treatment). Dietary treatments were organized in a 2 x 2 factorial arrangement: two sources of zinc, 60 mg/kg of Zn as ZnSO4.7H(2)O or 60 mg/kg of Zn as zinc amino acid complexes (ZnAA) combined with two levels of vitamin E (50 or 100 IU/kg). Zinc and vitamin E were added to a wheat/rye-based diet that was designed to create a mild nutritional challenge. From day 28 until day 36 (finisher period), all birds were subjected to chronic cyclic high temperatures (32 degrees C +/- 2 degrees C and RH 55-65% for 6 h daily). The combination of ZnAA and 50 IU/kg of vitamin E improved weight gain in the starter (day 0-10), finisher (day 28-36) and overall period (day 0-36) and feed conversion ratio in the starter (day 0-10) and finisher phase (day 28-36). Providing Zn as ZnAA significantly improved villus length and villus/crypt ratio in the starter, grower and finisher period and decreased infiltration of T-lymphocytes and ovotransferrin leakage in the finisher period. In conclusion, providing broilers with a diet supplemented with ZnAA and a vitamin E level of 50 IU/kg, resulted in better growth performance as compared to all other dietary treatments. Interestingly, under the conditions of this study, positive effects of ZnAA on performance did not occur when vitamin E was supplemented at 100 IU/kg in feed. Moreover, providing zinc as zinc amino acid complex improved intestinal health