| The experiment was conducted to investigate the effects of different phosphorus sources from mono-dicalcium phosphate (MDCP) or dicalcium (DCP) and different types from powdery or granular on the performance of laying hens and bone quality. A total of 600 commercial Lohmann pink-shell laying hens of 32-wk-old were randomly assigned to 1 of 5 diets involing 1 control plus 2×2 factorial completely randomized arrangement. The corn-soybean meal basal diet contained 0.125% non-phytate phosphate (NPP). Feed and water ad libitum. Each treatment consisted of 8 replicates of 15 hens each.The experiment lasted 12 wk. The result showed:There was no significant difference on performance by phosphorus source,phosphorus types and source by type interaction in laying hens(P>0.05). Granular MDCP could significantly increase 1-4 wks on average daily feed intake(P<0.05). Hens fed the basal diet had lowest egg production, feed intake and egg weight while the rate of mortality and feed to egg ratio was the highest(F<0.05).No significant difference was observed on dirty egg rate, eggshell strength, egg shell thickness, egg weight, yolk color, Haugh unit, high protein, egg shape index by phosphorus source,phosphorus types and source by type interaction in laying hens(P>0.05). Hens fed the basal diet had highest cracked and broken in 5-8 wks and superlative soft in 1～12 wks. At the same time, egg shell percentage, egg color and egg yolk proportion in 4th wk, egg yolk weight in 4th wk and 8th wk, and the A value of egg shell color in 4th wk,8th wk and 12th wk and the L value of 12th wk were significantly decreased (P<0.05). Compared with DCP,MDCP significantly inhanced yolk percentage at 12th wk, meanwhile, A value and B value of egg shell color were show she same results (P<0.05). Compared with powdery, granular phosphate significantly increase unqualified egg(including double yellow, small, deformity and the sandpaper) at 1～12 wks and yolk proportion at 4th wk (P<0.05), but the latter was no significant difference in 8th and 12th wk (P<0.05). Compared to the powdery, granular phosphate improved A value of egg shell color at 8th wk (P<0.05). Phosphorus and phosphorus types interaction has significanlt effects in unqualified egg in 1～12 wks and A value and B value in eggshell at 12th wk (P<0.05).There was no significant difference on serum calcium and phosphorus, alkaline phosphatase by phosphorus source,phosphorus types and source by type interaction in laying hens (P>0.05). Hens fed the basal diet significantly decreased serum calcium and phosphorus, reduce the content of tibia ash and calcium,the dry matter, calcium and phosphorus utilization (P<0.05). Compared with DCP, MDCP significantly decrease tibia phosphorus (P<0.05), meanwhile,MDCP tend to decreased dry matter utilization,but the difference was not significant compare with DCP (P=0.060). Compared to the powdery, granular phosphate improved CT and PTH in serum, nevertheless, tibia calcium, tibia ash, calcium and phosphate digestibility was significantly lower than powdery (P<0.05). Phosphorus and phosphorus types interaction has significanlt effects on PTH in serum and tibia ash (P<0.05).Finally, conclusion from the following three aspects. At first, the basal diet with 0.125% NPP can not meet the requirement of 32～44 wks old laying hens. Secondly, In the 3.5% calcium level and 0.32% available phosphorus nutritional level, MDCP feeding effects was in the same with DCP. Eventually, powdery phosphate calcium and phosphate utilization was lower than granular. |
