RESUMO
Objetive. To determine the effects of high temperature, the high humidity and the index on production performance in layer chickens supplemented with vitamins C and E. Materials and methods. The experiment was carried out from July 14th to August 15th. A total of 720 L33 layer chickens, 39 weeks old, were divided at random into four groups (180 birds/group), by replicates (n=4): Control Group) was fed with a basal diet and treatment groups were fed with the basal diet supplemented with either 150 mg of l-ascorbic acid/g of diet (Group Vit. C) or 150 mg of dl-α-tocopherol acetate /kg, of diet (Group Vit. E), and 150 mg of l-ascorbic acid /kg of diet plus 150 mg of dl-α-tocopherol acetate/kg of diet (Group Vit C + E). Results. Egg/bird were higher (p<0.05) in all treatment groups when compared to control group, but p value was highly significant in vitamin E treated group. Likewise, the laying index was different (p<0.05) in all treatment groups when compared to control, and P value was highly significant in vitamin E treated group. Although, viability was not affected by vitamin C, vitamin E and vitamin C+E groups when compared to control (p>0.05). However, feed consumption and conversion were different (p<0.05) in treatment groups when compared to control group. Conclusions. Dietary supplementation with 150 mg vitamin C and/or 150 mg vitamin E increased production performance in heat stressed layer chickens.