Effects of Calcium and Phosphorus Levels on Production Performance and Endocrine in New Yangzhou Chickens

600 New Yangzhou chickens which were 36-week-old and laying,by 2 × 2 factor for the complete random divided into four treatments(high calcium and low phosphorus treatment,high calcium and high phosphorus treatment,low calcium and low phosphorus treatment,low calcium and high phosphorus treatment),each treatment had five repeats,feeding corn-soybean meal diet with different levels of calcium and phosphorus,this article studied in 42d the effects of different levels of calcium and phosphorus on laying hen performance,eggs quality,endocrine and tibia quality.The average of laying rate in high calcium and high phosphorus were significantly higher than two low calcium treatments(P0.05),weight gain in high calcium and high phosphorus were significantly higher than the other treatments(P0.05),the specific gravity of eggs,eggshell strength,eggshell thickness and eggshell proportion also were significantly higher than the other treatment(P0.05).High calcium and high phosphate treatment of E2 level was significantly higher than low calcium and low phosphorus treatment(P0.05),BGP,PTH,CT,tibia index and tibia mineral density each treatment the difference was not significant.The results show that,under the conditions of thermal stress,dietary calcium and phosphorus levels were 3.5%,0.32%,about 11∶ 1,laying hen production performance,egg quality,bone metabolic profile and BGP,CT,PTH,E2 were desirable.