Circadian rhythms and dynamic dietary calcium feeding affect laying performance, calcium and phosphorus levels in laying hens

摘要

This study was conducted to determine the effects of dynamic feeding low and high Ca in layer diets on laying performance, calcium, and phosphate concentration in both serum and tibia. 180 Brown Hy-line, 41weeks old of laying hens were randomly distributed into 3 groups with 6 replicates and each replicate was 10 birds. During the 10-week experiment period, control group (CON group) received control diet (contained 3.4% Ca) at both 0730 and 1530h, low-high group (LH group) received low Ca diet (contained 3.2% Ca) at 0730h and high Ca diet (contained 3.6% Ca) at 1530h, while high-low group (HL group) receivedthe contrary to the LH group. Blood and tibia samples were collected at 4h intervals. The dynamic Ca feeding schedule exerted significant effects on Ca intake in the morning and afternoon, also on feed conversion ratio (FCR) of the HL group comparing to the LH group (p0.05). Serum Ca in the LH group were lower at 0000, 0400 and 1600h comparing with the CON group (p0.05), and serum Ca: P ratio values in the LH group were lower at 0000, 0800, and 2000h comparing with the CON group (p0.05). These results indicated that dynamic feeding Ca improved FCR and affected the circadian variation of serum Ca concentration in laying hens.