Effect Of Various Dietary Phosphorus Levels And Supplementation Phytase On Growth Performance And Nutrient Digestibility In Cherry Valley Duck

Phosphorus is vital mineral to ducklings. However, the research on phosphorus requirement of duckling is limited at present, furthermore, the optimal phosphorus level and phytase effect in corn-mixed meal diet is not well documented. The two factorial quadratic regression combination design was conducted to study the effect of supplementing phytase in a typical diet at various phosphorus levels on nutrient digestibilities in cherry valley duck. 660 1-day-old (initial weight 57.28～ 57.68g) ducks were divided by weight into 11 treatments with 4 replicates per treatment and 15 ducks per replicate. Eleven corn-mixed meal diets were randomly assigned to each treatment The phytase levels were 0 1U, 64 IU, 500 1U, 9361U, 1000 IU and the inorganic phosphorus levels were 0.00%, 0.03%, 0.25%, 0.47%, 0.50%. The experiment stage was from 0 to 14day .Body weight gain of day 1 and 14, feed conversion ratio and feed intake was measured. The metabolic experiment was conducted using one duck of each cage on day 14. Duck litter was collected for determining the nutrient availability. At the end of metabolic experiment, blood was collected from duck heart for determining serum calcium, phosphorus concentration and alkaline phosphatase activity. The left tibia was collected to determine bone breaking strength, bone calcium, phosphorus and ash concentration. All criterion was analyzed by Excel according to 2-factorial quadratic combination design and regression model was y=b₀+b₁X₁+b₂X₂ +b₃X₁²+b₄X₂²+b₅X₁X₂ which was used to calculate the optimal levels of inorganic phosphorus and phytase. The results indicated: BWG, FI, G/F, digestibilities of energy, protein, calcium and phosphorus, tibia breaking strength, calcium concentration, phosphorus concentration, ash concentration and serum calcium concentration varied quadratically with the various combination of inorganic phosphorus and phytase, but phytase did not significantly affect those criterion. According to the regression model, the inorganic phosphorus levels were 0.38%, 0.38%,0.38%, 0.35%, 0.36%, 0.30%, 0.30%, 0.20%, 0.32%, 0.37%, 0.36% and 0.38% when criterion attained its optimum (600.37g, 38.78g, 1.29, 71.61%, 69.16%, 65.22%, 2.00%, 83.84kg/cm2, 27.57%, 11.63% and 53.75%, respectively) . In this research, BWG and tibia phosphorus concentration reflected the phosphorus requirement of ducks (0-14 day) and the optimal adding level of inorganic phosphorus was 0.38%.