Evaluation of one-alpha-hydroxy-cholecalciferol alone or in combination with cholecalciferol in Ca—P deficiency diets on development of tibial dyschondroplasia in broiler chickens

This experiment was conducted to determine whether dietary cholecalciferol will alleviate a calcium and phosphorous (Ca—P) deficiency when one-alpha-hydroxy-cholecalciferol, 1α(OH)D(3), is supplemented, and to determine the effects of adequate and inadequate Ca—P when 1α(OH)D(3) is supplemented and vitamin D(3) 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 Ca—P + cholecalciferol + 5 μg/kg 1α(OH)D(3); treatment B, inadequate Ca—P + cholecalciferol + 5 μg/kg 1α(OH)D(3); treatment C, inadequate Ca—P + 5 μg/kg 1α(OH)D(3). 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 D(3.) The Ca—P 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 Ca—P 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 < 0.05). The broilers fed inadequate Ca—P diets with cholecalciferol were unable to achieve the same tibia ash and incidence of TD as those fed Ca—P adequate diets (P < 0.05). In conclusion, this trial suggests that broilers fed an inadequate Ca—P diet with 1α(OH)D(3) and adequate level of cholecalciferol are unable to sufficient bone formation. There was no indication that 1α(OH)D(3) in the absence of cholecalciferol was effective in reducing TD whereas it could improve tibia ash.