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This experiment was conducted to determine whether dietary cholecalciferol will alleviate a calcium and phosphorous (CaP) deficiency when one-alpha-hydroxy-cholecalciferol, 1α(OH)D3, is supplemented, and to determine the effects of adequate and inadequate CaP when 1α(OH)D3 is supplemented and vitamin D3 is adequate. A total of 144 one-d-old broiler chicks (Ross 308) were allocated to 3 treatments. The dietary treatments were as follows: treatment A, adequate CaP + cholecalciferol + 5 μg/kg 1α(OH)D3; treatment B, inadequate CaP + cholecalciferol + 5 μg/kg 1α(OH)D3; treatment C, inadequate CaP + 5 μg/kg 1α(OH)D3. All diets were mixed with 500 FTU/kg of phytase, and cholecalciferol was provided in 5,000 IU/kg except for treatment C that fed diets without vitamin D3. The CaP levels in the adequate diets were 0.90% Ca, 0.66% total phosphorus (tP); 0.75% Ca, 0.59% tP; 0.69% Ca, 0.54% tP for the starter, grower and finisher periods. At d 42 of age, broilers were inspected for incidence and severity of tibial dyschondroplasia (TD). The results showed that inadequate CaP supplementation with cholecalciferol significantly decreased the incidence of TD, score and tibia ash compared with broilers fed the same diet in the absence of cholecalciferol (P |
