Performance and bone health of broilers reared under artificial lighting and supplemented with different levels of vitamin D3

ABSTRACT This study aimed to investigate the effects of different levels of vitamin D3 in broiler diets on performance and bone health. A total of 360 one-day old male Cobb500® broiler chicks were subjected to five treatments of different levels of vitamin D3 in diets during two rearing phases: 0 IU/kg in both phases; 625 IU/kg in starter and 500 IU/kg in grower phase (25% of commercial inclusion); 1,250 IU/kg in starter and 1,000 IU/kg in grower phase (50% of commercial inclusion); 1,875 IU/kg in starter and 1,500 IU/kg in grower phase (75% of commercial inclusion); and 2,500 IU/kg in starter and 2,000 IU/kg in grower phase (100% of commercial inclusion). The traits studied weekly were feed intake, body weight, feed conversion, and viability. At 21 and 35 days of age, tibiae and femurs were removed, dissected, and evaluated for dry matter (DM), ash (%MM), calcium (%Ca), phosphorus (%P) and breaking strength. At 35 days of age, the bones were subjected to histopathological analysis for macro- and microscopic morphological evaluation. Data were subjected to regression analysis, using α = 0.05. The variables of percentage %MM, %Ca, %P, and breaking strength experienced a positive linear effect up to the supplementation levels of approximately 25% of inclusion. The histopathological analysis found that the group that received the diet with 100% inclusion of vitamin D3 presented lesions compatible with osteopetrosis and tibial dyschondroplasia. The observed results showed that for isonutritive diets, reduced levels of vitamin D3 guaranteed performance during the evaluated period while the use of 100% of vitamin D3, as commonly used, can cause bone diseases and harm the welfare of broilers.