Effect Of Dietary Phosphorus And The Ratio Of Calcium To Phosphorus On Performance And Phosphorus Uptake Of Laying Hens

Non-phytate diets poultry feedstuff only about 30% of phosphorus is for poultry can be directly used to meet other needs of animal production and laying poultry diets must add additional inorganic phosphorus, but these additions phosphorus can not be completely absorbed by the excess phosphorus in the form of feces, urine phosphorus excreted, causing environmental pollution, improve farming costs. On the one hand China’s phosphorus scarcity of resources, on the other hand the use of phosphorus is not sufficient, resulting in excessive excretion of phosphorus serious waste. So an accurate assessment of the animal’s phosphorus requirements, improve utilization of dietary phytate phosphorus nutrition has become a hot research. In this experiment, of different levels of phosphorus and calcium and phosphorus ratio on high production performance of laying hens, blood biochemical parameters and bone characteristics and Na/Pi-IIb mRNA expression levels, combined in vitro Ussing technique test yielding inquiry layers phosphorus absorption and utilization mechanism designed for the rational use of high-yield and add layer ration phosphorus reference.Test Ⅰ:The effects of different levels of phosphorus and phosphorus ratio on the production performance of laying hens, serum biochemical parameters and bone Characters This experiment was conducted to study the impact of different levels of phosphorus and phosphorus ratio on the production performance of laying hens, serum biochemical parameters and bone traits. Using 2×3 crossover group trial design, each factor of three levels, a total of nine treatments with five replicates 9 chickens. Two factors are dietary dietary phosphorus (AP) levels of calcium and phosphorus than 3 phosphorus level of 0.25%, 0.30% and 0.35%, three levels of calcium and phosphorus ratio was 8:1,10:1 and 12:1. The results showed that:When the dietary phosphorus level was 0.35%, Ca:AP=10:1, laying hens can get a higher laying performance、a higher egg quality and skeletal traits.Test II:The effects of different levels of phosphorus and pH of laying hens in vitro intestinal absorption of phosphorusIn this study, two experimental design list, respectively, to explore the level of phosphorus and pH of laying hens in vitro intestinal absorption of phosphorus, intended to assess the application Ussing chamber phosphorus feed the appropriate choice of medium phosphorus concentration and pH values provide a reference. Each factor of three treatments were phosphorus levels of 0.25%,0.30%and 0.35%, pH values of 6.4,7.4 and 8.4. Select 24 30-week-old Roman laying hens with similar body weight were randomly assigned to six treatments, each treatment 4 replicates of 1 chicken, duodenum, jejunum and ileum, using Ussing chamber culture system 60min. The results show that:the same level of phosphorus, phosphorus absorption in the intestines between no significant difference (P>0.05), but the duodenum and phosphorus absorption rate than jejunum, ileum slightly higher. pH 7.4 duodenum, jejunum and back to the field P uptake were significantly higher than pH6.4 and pH8.4 group (P<0.05), and each experimental group was significantly higher than the resistance of the duodenum and jejunum, ileum resistance, resistance difference between jejunum and ileum were not significant. When the pH level of 6.4-8.4, the pH increases, the resistance of each bowel showed the first increase and decrease, pH7.4 duodenum resistance was significantly higher than 6.4 and 8.4 groups, pH6.4 and 8.4 group the difference was not significant; the same results jejunum and ileum and duodenum law. Each experimental group were higher than the resistance of the duodenum jejunum and ileum.In laying hens in animal models to assess the phosphorus feed with Ussing chamber technique, the appropriate culture medium, pH 7.4; phosphorus content of about 0.3% is appropriate.Test III:Effect of different levels of phosphorus and phosphorus ratio of hens intestinal Na/Pi-IIb gene mRNA expressionDifferent levels of phosphorus and calcium and phosphorus ratio on high-yielding layers intestinal Na/Pi-IIb gene mRNA expression. In the first test in the gut as material layers, using RT-PCR for each bowel Na/Pi-IIb mRNA expression levels were measured. The results showed that:(1) diet AP levels and Ca:AP having a significant effect on the small intestine hens Na/Pi-IIb mRNA expression level,0.25% AP diets intestinal Na/Pi-IIb mRNA expression was higher than 0.30% and 0.35% group. (2) the duodenum and jejunum Na/Pi-IIb mRNA expression with Ca:AP improvement increases. Small intestine intestines Na/Pi-IIb mRNA expression levels duodenum> jejunum> back to the field.Conclusion:(1) To assess the model animal feed hens with phosphorus Ussing chamber technique, the appropriate culture medium, pH 7.4, available phosphorus content of about 0.3% is appropriate.(2) Dietary AP level 0.35%,Ca:AP=10:1 yielding layers can obtain a higher production performance, egg quality and excellent performance of the tibia.(3) 0.25% AP diets intestinal Na/Pi-IIb mRNA expression level higher than 0.30% and 0.35% group. Duodenum and jejunum Na/Pi-IIb mRNA expression with Ca:AP improvement increases; small intestine intestines Na/Pi-IIb mRNA expression levels duodenum> jejunum> ileum.