Impact of dietary supra-nutritional levels of vitamins a and e on fertility traits of broiler breeder hens in late production phase

This study aimed to evaluate the effect of dietary supplementation with supra-nutritional levels of vitamins A and E on fertility and productivity traits of Ross-308 broiler breeder hens during the late production phase. The trial was conducted for nine weeks, from 61 to 69 weeks of age, and designed to test four levels of vitamin A (100, 125, 150 and 200% above the Ross catalogue recommendations) and four levels of vitamin E (100, 200, 300 and 400% above Ross catalogue instructions), maintaining constant the other rearing conditions. Vitamins were combined in 16 treatments, with four replicates per treatment each including seven females, and one rooster broiler was used in every two replicates. A total of 448 hens and 32 roosters were used in the experiment. Fertility parameters were weekly evaluated. According to the results, egg-related parameters (number and weight of eggs, non-conform eggs and hatchability) were not affected by treatment, but dietary treatments increased and extended the hens’ productivity for an additional six weeks in most experimental groups. The chick-related parameters (number and weight of produced chicks) and chick yield differed significantly among groups (p < 0.05). The best economic index was found in birds fed basal-diet plus 100% of vitamin A and 200% of vitamin E. In conclusion, the present study showed that a combination of dietary supra-nutritional levels of vitamins A and E allowed to extend the laying period and to reduce the decline of fertility in older breeder hens at the end of the laying stage; in particular, among the 16 tested treatments, feeding of supra-nutritional level of 100% vitamin A and 200% vitamin E lead to the best results