Study on Appropriate Levels of Dietary Calcium and Phosphorus for"817"Broilers at 1 to 21 Days of Age
The aim of this experiment was to study the appropriate levels of dietary calcium and phosphorus for"817"broilers(AA parental parent breeder cocks×Roman brown laying hens commercial hens)at 1 to 21 days of age.A two-factor experimental design was used,with calcium levels of 0.90％,1.00％and 1.10％,and phosphorus levels of 0.65％,0.68％and 0.71％,respectively.A total of 9 experimental diets were formu-lated.Eight hundred and sixty-four 1-day-old healthy"817"broilers were randomly divided into 9 treatments with 6 replicates in each treatment and 16 chickens in each replicate.The experiment lasted for 21 days.The re-sults showed as follows:1)dietary calcium level had a significant effect on the average daily gain of hybrid broilers(P＜0.05),and the average daily gain of broilers in the 0.90％calcium group was significantly higher than that in the 1.10％calcium group(P＜0.05);dietary phosphorus level significantly affected the feed to gain ratio of hybrid broilers(P＜0.05),and the feed to gain ratio of broilers in the 0.71％phosphorus group was significantly lower than that in the 0.68％phosphorus group(P＜0.05).2)Dietary calcium level signifi-cantly affected the apparent metabolic rate of phosphorus of hybrid broilers(P＜0.05),and the apparent meta-bolic rate of phosphorus was significantly higher in the 0.90％and 1.10％calcium groups than that in the 1.00％calcium group(P＜0.05);dietary phosphorus level significantly affected the apparent metabolic rate of calcium of hybrid broilers(P＜0.05),and the apparent metabolic rate of calcium was significantly higher in the 0.68％phosphorus group than that of the 0.65％phosphorus group(P＜0.05);there was a significant interac-tion between the levels of dietary calcium and phosphorus on the apparent metabolic rates of both calcium and phosphorus(P＜0.05).3)Dietary calcium level had a significant effect on the deposition rates of calcium and phosphorus of hybrid broilers(P＜0.05),and the deposition rates of calcium and phosphorus of broilers in the 0.90％calcium group were significantly higher than those of the 1.00％calcium group(P＜0.05);dietary phosphorus level had no significant effects on the deposition rates of calcium and phosphorus of hybrid broilers(P＞0.05).4)Dietary calcium level significantly affected the serum phosphorus content of hybrid broilers(P＜0.05),and the serum phosphorus content of broilers in the 0.90％and 1.10％calcium groups were significant-ly higher than that in the 1.00％calcium group(P＜0.05);dietary phosphorus levels significantly affected the serum phosphorus content of hybrid broilers(P＜0.05),and the serum phosphorus content of the 0.71％and 0.68％phosphorus groups was significantly higher than that of 0.65％phosphorus group(P＜0.05).Dietary phosphorus level significantly affected the serum alkaline phosphatase activity of hybrid broilers(P＜0.05),and the serum alkaline phosphatase activity of 0.65％phosphorus group was significantly higher than that of the 0.71％phosphorus group(P＜0.05).There was a significant interaction between dietary calcium and phosphor-us levels on serum phosphorus content and alkaline phosphatase activity of hybrid broilers(P＜0.05).5)The prediction models of daily calcium and phosphorus requirements of hybrid broilers at 1 to 21 days of age were established by factorial method,they were YCa=0.210W0.75+0.010 △W and Yp=0.124W0.75+0.008 △W(W0.75 was metabolic weight;△W was average daily gain),respectively.According to the prediction models of daily calcium and phosphorus requirement and average daily feed intake,the appropriate levels of dietary calcium and phosphorus of"817"broilers at 1 to 21 days of age are 0.94％and 0.67％,respectively.[Chinese Journal of Animal Nutrition,2024,36(8):5026-5038]
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