Studies On The Requirments Of Calcium And Phosphorus For Beijing Ducklings

Two experiments were conducted to determine calcium(Ca) and nonphytin phosphorus(NPP) requirements for Pekin ducklings,and to estimate effects of calcium and phosphorus levels on growth and bone healthy of Beijing ducklings(experimentⅠfor period between weeks 0 to 2, experimentⅡfor period between weeks 3 to 6). Experiments had a 5×4 factorial arrangment of treatments with Ca at 0.40%,0.60%,0.80%,1.00%,1.20% and NPP at 0.20%,0.30%,0.40%,0.50% in experimentⅠ,or with Ca at 0.30%,0.48%, 0.66%,0.84%, 1.15% and NPP at 0.17%,0.25%,0.33%,0.42% in experimentⅡ.Weight gain,feed consumption,feed conversion,tibia ash content,Ca and P content of ash,and levels of serum Ca,NPP and ALP were used as criteria for determination of the optimum diet Ca and NPP levels required by the Pekin ducklings. The results were as follws:1. Kickets were observed when ducklings received diets containing 0.20% NPP and 0.80%,1.00% or 1.20% Ca,in experimentⅠ,and osteoporosis were observed in duckinglings received diets containing 0.17% NPP and 0.66%,0.84% or 1.15% Ca,in experiment Ⅱ.Ca,P of diets and interaction of them all influenced weight gain,feed consumption and feed efficiency significantly.The higher levels of Ca and P improved weight gain,feed consumption and feed conversion.But the levels of Ca 0.84% and 1.15%(the highest level) and the highest level of P (NPP0.42%) reduced weight gain,in experiment Ⅱ,and the highest level of Ca(1.20%) combined with the highest level of NPP(0.50%) decreased feed consumption and weight gain,in experimentⅠ.Tibia ash contents were upgraded with the levels of diets Ca and P increased.The highest level of diets Ca or NPP did not reduce the tibia ash content.Ca levels of diets had significant effects on Ca and P contents of ash,in both experiments.P level of diets affected P content of ash significantly in both experiments,and had significant influence on Ca contents of ash only in experiment Ⅱ.The interaction of Ca and P did exert a significant influence on P contents of ash only in experiment Ⅱ,had no effect on Ca contents of ash in both experiments.Ca and P levels of diets had no effects on levels of serum Ca.Increasing levels of diets Ca reduced contents of serum P,upgraded serum ALP significantly,only in ducklings recived lowest NPP diets(0.20% NPP in experimentⅠ,0.17% NPP in experiment Ⅱ).The means of serum P and ALP had no significant difference among other groups.The results indicate that the contents of serum Ca and P are not good indictors for the determination of the requirements of diet Ca and P for Pekin ducklings.The higher levels of Ca reduced P absorptions of ducklings received lowest NPP diets,which made the ducklings not maintain levels of serum P normally.In order to enhance the levels of serum P,the ducklings had to increase bone resorptions.For too low absorption of P,and after a long-team resorption of bone,the ducklings could not normalize their's serum P levels still,but caused rickets(in experimentⅠ)or osteoporosis(in experiment Ⅱ).The requirements of Ca and NPP,for maximum growth,were 0.83% and 0.39% in the period between weeks 0 to 2 , 0.62% and 0.35% in the period between weeks 3 to 6,respectively,determined by regression analysis of body weight gain against Ca and NNP levels in the diet.The optimal requirements of Ca and NPP,for maximum tibia ash content, were 0.86% and 0.43% in the period between weeks 0 to 2 , 0.90% and 0.39% in the period between weeks 3 to 6,respectively,determined by regression analysis of tibia ash content against Ca and NNP levels in the diet.