Effects Of Different Supplement Calcium Methods On Performance, Tibia Quality And Egg Quality Of Laying Hens

Now, the standard of hens feeding in China and NRC provided the calcium requirements of young hens and laying hens. However, the calcium requirements of laying hens from beginning to peak have not determine. This study was conducted to investigate the effects of different methods of supplement calcium on the performance, serum biochemical indices, the tibia quality and egg quality of laying hens at 18 weeks old, 5% of laying rate, 50% of laying rate and 90% of laying rate. In order to supply theoretical date for calcium using in diet of laying hens.The study was used randomly one-way ANOVA, four hundred and eighty 18-week-old Hy-Line gray commercial layers were selected and randomly assigned 4 groups. Each group has four replicates and every replicate was thirty Hy-Line gray commercial layers. The different groups was supplemented different levels calcium in the diet(corn-soybean). The time points of supplement calcium in diet were at 18 weeks old, 5% of laying rate, 50% of laying rate and 90% of laying rate of layers. The method of supplement calcium were Ⅰ group with 2.0%、2.2%、2.4%、3.75%, Ⅱ group with 2.0%、2.5%、3.0%、3.75%, Ⅲ group with 2.0%、3.0%、3.75%、3.75% and Ⅳ group with 2.0%、3.75%、3.75%、3.75%. The experiment lasted for 10 weeks, following a week adaptation, the trial lasted nine weeks. The results showed as follows:① The value of laying rate of laying hens in Ⅲ group were highest and were 8.71%(P<0.05), 4.01%(P>0.05), 5.81%(P<0.05) higher than that in Ⅰ, Ⅱ and Ⅳ groups respectively. Calcium level had no significant effects on the egg weight(P>0.05). The dry matter intake and breaking egg rate in Ⅰ group were significantly higher than that in others(P<0.05), but feed egg ratio had no difference in four treatments(P>0.05).② The pubic space in Ⅰgroup was significantly lower than that in other treatments(P<0.05), the hip width of Ⅲ, Ⅳ group were higher than that in Ⅰ, Ⅱ groups(P<0.05), but body length, keel length, tibial length and tibial girth of four treatments had no influence by calcium level in diet(P>0.05). The tibial strength in Ⅲ group were 21.05%(P<0.05), 14.63%(P<0.05), 7.68%(P>0.05) higher than that in Ⅰ, Ⅱ and Ⅳ groups respectively. The tibial weight and tibial calcium in Ⅲ group were significantly higher than that in Ⅰ, Ⅱ groups(P<0.05), but no difference with Ⅳ group(P>0.05).③ Serum calcium concentration in Ⅰ, Ⅱ groups was significant higher than that in Ⅲ, Ⅳ group when laying rate reached 50% of laying hens(P<0.05), and Ⅳ group was significant higher than that in Ⅰ, Ⅱ groups when laying rate reached 90%(P<0.05). About the serum phosphorus, the Ⅰ group was 21.84%(P>0.05), 35.95%(P<0.05) and 51.20%(P<0.05) higher than that in Ⅱ, Ⅲ, Ⅳ group when the laying rate reached 50%, however, there were no difference in four groups at the 90% laying rate(P>0.05). Serum PTH content of Ⅲ, Ⅳ group were significantly lower than that in Ⅰ group(P<0.05). Serum CT content of Ⅲ, Ⅳ group were significantly higher than Ⅰ, Ⅱ groups(P<0.05) and Ⅱ groups(P<0.05) respectively. Serum BGP content of Ⅲ, Ⅳ group were significantly lower than Ⅰ group(P<0.05), but no difference with Ⅱ groups(P>0.05).④ The calcium content of eggshell in Ⅲgroup was significantly higher than that in Ⅰgroup(P<0.05), but no difference with Ⅱ, Ⅳgroup(P>0.05) when the laying rate reached 50% of laying hens. Meanwhile, calcium level of diet had no significant on eggshell weight, eggshell strength, eggshell thickness, egg weight, yolk color and egg protein height(P>0.05). The eggshell color of Ⅲgroup was most uniform. When the laying rate reached 90% of laying hens, the eggshell calcium content of group was significant higher than that in Ⅲ Ⅰ, group(Ⅱ P<0.05), but no difference with Ⅳgroup(P>0.05). The value of eggshell weight, eggshell strength and eggshell thickness of Ⅲgroup were highest, and significant higher than that in Ⅰgroup(P<0.05), but no difference with Ⅳgroup(P>0.05). Egg weight, yolk color and egg protein height had no difference by calcium level of diet(P>0.05). The eggshell brightness of Ⅲgroup was significant higher than that in Ⅰ, Ⅱ, Ⅳgroup(P<0.05). In conclusion, the calcium level of diet with 3.0%, 3.75%, 3.75% at 5%, 50%, 90% of laying rate can improve the egg quality and eggshell quality, depress the eggshell crack.In conclusion, the calcium level of diet with 3.0%, 3.75%, 3.75% at 5%, 50%, 90% of laying rate can improve the performance, stable the bone quality, increase the egg quality and eggshell quality and depress the eggshell crack.