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

摘要

This experiment was conducted to determine whether dietary cholecalciferol will alleviate a calcium and phosphorous(Ca-P) deficiency when one-alpha-hydroxy-cholecalciferol,1 a(OH)D_3,is supplemented,and to determine the effects of adequate and inadequate Ca-P when 1 a(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 mg/kg 1 a(OH)D_3;treatment B,inadequate Ca-P + cholecalciferol + 5 mg/kg 1 a(OH)D_3; treatment C,inadequate Ca-P + 5 mg/kg 1 a(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(t P); 0.75% Ca,0.59% t P; 0.69% Ca,0.54% t P 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 1 a(OH)D_3 and adequate level of cholecalciferol are unable to sufficient bone formation.There was no indication that 1 a(OH)D_3 in the absence of cholecalciferol was effective in reducing TD whereas it could improve tibia ash.