Effects of Phosphorus Source and Level on Performance and Eggshell Quality of Laying Hens

The experiment was conducted to investigate the effects of different phosphorus levels from mono-dicalcium phosphate(MDCP) or dicalcium phosphate(DCP) on performance and eggshell quality of laying hens.A completely randomized design involving a 2×7 factorial arrangement of treatments was used in this study.Two phosphorus sources were MDCP and DCP,and seven phosphorus supplemental levels were 0,0.05%,0.10%,0.15%,0.20%,0.25% and 0.30%,respectively.A total of 1 170 commercial Lohmann pink-shell laying hens aged 25 weeks were randomly assigned to 13 treatments with 6 replicates each and 15 hens in each replicate.The corn-soybean meal based diet contained 0.12% non-phytate phosphate(NPP) and calcium level of all diets was 3.5%.The experiment lasted for 24 weeks.The results showed as follows:there were no significant interactions between phosphorus source and phosphorus level in the laying performance and eggshell quality(P0.05).During the whole experimental period,hens fed the basal diet had the lowest average daily egg production,average daily egg mass,average daily feed intake(ADFI) and average egg weight,and the highest feed to egg ratio,cracked or broken,and malformation egg percentage(P0.05).Phosphorus source and level had no significant effects on eggshell thickness(P0.05).When hens were fed the diets with NPP supplemental level between 0.05% and 0.30%,there were no significant differences in average daily egg production,feed to egg ratio(except for 1 to 4 weeks),mortality,cracked or broken,soft,and malformation egg percentage(P0.05).When hens were fed the diets with NPP supplemental level between 0.10% and 0.30%,there were no significant differences in average daily egg mass(P0.05).With dietary NPP level increasing,average egg weight and ADFI increased firstly,and then decreased.The results indicate that MDCP can completely replace DCP in the diet of laying hens.The suitable NPP level in the corn-soybean meal based diet is 0.22%,and MDCP supplemental level is 0.48% for laying hens aged from 25 to 49 weeks.