Effect of Surfeit Concentrations of Vitamin D3 on Performance, Bone Mineralization and Mineral Retention in Commercial Broiler Chicks

An experiment was conducted to see the effect of higher concentrations of vitamin D3 in diets containing sub optimal levels of calcium (Ca) and non-phytate phosphorus (NPP) in broiler chickens. Maize-soybean meal based starter and finisher reference diets (RD) prepared to contain 1.0% and 0.9% Ca, 0.45 and 0.35% NPP, respectively. The RD contained 1200ICU D3/kg. Another basal diet (BD) was prepared to contain 0.4% Ca and 0.2% NPP. The BD was supplemented with D3 at 4 different concentrations such as 1200, 2400, 4800 and 9600ICU/kg. Each diet was fed to 11 replicates of 5 chicks each during experimental period of 0 to 6 weeks of age. The body weight gain decreased significantly with reduction in levels of Ca and NPP in diet compared to those fed RD. Supplementation of vitamin D3 to the low Ca and NPP diet, though improved the weight gain significantly but not at per with RD. The feed efficiency was not affected by concentrations of Ca, NPP and D3 in diet at 36d of age. The relative weight of tibia, tibia breaking strength and tibia ash content decreased significantly with reduction in Ca and NPP levels in diet. Supplemental D3 replenished the tibia ash content and enhanced tibia weight and strength. Supplemental D3 non-linearly increased the serum Ca, P, acid and alkaline phosphatase contents in serum. Concentrations of Ca, P, Fe, Zn, Mn and Cu in excreta decrease non-linearly with increase vitamin D3 concentration in BD. It is concluded that higher levels of D3 supplementation to low Ca and NPP diet improved the performance partially but not at per with diet containing the recommended concentrations of Ca and NPP in broiler diet