| The experiment were carried out to determine the effects of dietary phosphorus source and level on the performance, tibia quality, and apparent nutrient digestibility in broilers. The objectives of this study were to find the suitable level of MDCP and MCP in broiler diet. According to the NRC(1994) and domestic research, the suitable NPP level of white feather broiler are 1-21d:0.45%,22-42d:0.31%. The supplemental levels were designed according to the RBV of MDCP and MCP relative to DCP. The RBV of MDCP are 111.5%,106% and 100%, the corresponding NPP level are 1-21 d NPP%:0.42,0.44,0.45; 22-42d NPP%:0.29,0.30,0.31. The RBV of MCP are 139%,120% and 100%, the corresponding NPP level are 1-21d NPP%:0.38,0.41,0.45; 22-42d NPP%:0.26,0.28,0.31. We set a DCP control group in every NPP level. The MDCP experiment is a 2 X 3 design,2 phosphorus sources(DCP and MDCP),3 phosphorus level; The MCP experiment is a 4 X 3 design,4 phosphorus sources(DCP and MCP1, MCP2, MCP3),3 phosphorus level. There were 17 treatments,7 replicates per treatment, and every replicate have 20 birds, in total 2380 Cobb broilers. Result:1) The 1-21 d feed intake of group MDCP was significantly higher than group DCP (P<0.05). The 1-21 d body weight gain and feed intake of MCP3 group were significantly higher than MCP1, MCP2 and DCP(P< 0.05). The MCP1, MCP2, and DCP group have no difference on performance, and the MDCP and MCP group also have no difference on performance under the suitable NPP level(1-21d:0.45%,22-42d: 0.31%). The body weight gain and feed intake were increased with the rise of feed NPP level (P<0.01).2) Compared with DCP, MDCP increased the 21 d tibia ash significantly (P<0.05), MCP increased the 21d tibia ash,Ca and P significantly (P<0.05). The MDCP and MCP group also have no difference on tibia quality under the suitable NPP level. The 21d tibia ash,Ca, P and breaking strength were increased with the rise of feed NPP level (P<0.01).3) The 42d serum phosphorus of group MDCP was significantly higher than group DCP (P<0.05). The MCP groups also had a tendency to increase the 21d serum phosphorus content(P=0.067). The 21d serum AKP of MCP group were lower than DCP (P<0.01). The 21d and 42d serum phosphorus increased, and 21d serum AKP reduced with the rise of feed NPP level (P<0.01).4) The results of metabolic experiment showed that: The apparent utilization ratio of phosphorus of MDCP group in earlier stage was significantly higher than DCP (P<0.05). The MCP group in earlier and later stage were higher than DCP (P<0.01). MCP1, MCP2, and MCP3 have no difference(P>0.05).Conclusion:1. When use the DCP in broiler diet, the suitable NPP level (1-21d:0.45%,22-42d:0.31%) is correct, reducing the NPP level will loss the performance and bone quality.2. The average RBV of MDCP, MCP1, MCP2, MCP3 relative to DCP are 103%,102%,102%,105%. When replace DCP (P,18.44%) by MDCP (P:20.84%), MCP1 (P:22.34%), MCP2 (P:22.69%), MCP3 (P:22.53%) in broiler diet, we reference to the following equivalent type:0.86kgMDCP=1kgDCP,0.80kgMCP1=1kgDCP, 0.79kgMCP2=1kgDCP,0.78kgMCP3=1kgDCP.3. The phosphorus emissions of MDCP and MCP group are lower than DCP group. In this experiment condition, compared with DCP, MDCP, MCP 1, MCP2 and MCP3 can reduce fecal phosphorus emissions 0.50,1.40, 1.16,1.71 gram per one broiler in the whole stage(1-42d). |
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