Effects of 25-Hydroxyvitamin D₃ supplementation as a partial replacement for vitamin D₃ on laying performance, egg quality, and bone traits in late-stage laying hens

The objective of this study was to assess the impact of dietary 25-hydroxy vitamin D3 (25OHD3) supplementation during the late laying hens on egg quality, hen performance and bone computerized tomography (CT) scanning parameters. In total, 24,862 Hy-Line Brownmax hens of 61 weeks old were randomly divided into two groups: the control group (n = 12,368) received a diet containing vitamin D3 at 3,000 IU/kg, and the treatment group (n = 12,494) received a diet containing vitamin D3 at 1,500 IU/kg and 25OHD3 at 1,500 IU/kg. The dietary intervention from 61 weeks of age to 75 weeks of age. At the start of the supplementation period, 2,400 hens were randomly selected (1,200 from each group) for individual body weight measurements, which were repeated after 15 weeks of dietary treatment. The three hens per group were randomly euthanized at 72 weeks of age. The femoral bones were harvested and analyzed using histomorphometry and micro-CT scanning. A significantly reduced feed intake was observed for hens in the treatment group compared with the control group (120.0 vs. 125.4 g/day, P < 0.001). No effects of 25OHD3 supplementation on body weight, body weight gain, or FCR were found (P > 0.05). Eggshell thickness was higher in the treatment group compared with the control group (0.390 vs. 0.380, P = 0.030). The egg mass in the treatment group was significantly lower than in the control group (53.3 ± 0.4 g vs. 56.2 ± 0.4 g, P < 0.001). Furthermore, in the treatment group, bone volume, bone surface, bone surface density, and connectivity density were higher in the treatment group compared to the control group (P < 0.05). However, trabecular bone or the trabecular area were not affected (P > 0.05). In conclusion, dietary supplementation with 25OHD3 In conclusion, 25OHD3 supplementation affected egg quality and bone trait of late-production laying hens. The objective of this study was to assess the impact of dietary 25-hydroxy vitamin D3 (25OHD3) supplementation during the late laying hens on egg quality, hen performance and bone computerized tomography (CT) scanning parameters. In total, 24,862 Hy-Line Brownmax hens of 61 weeks old were randomly divided into two groups: the control group (n = 12,368) received a diet containing vitamin D3 at 3,000 IU/kg, and the treatment group (n = 12,494) received a diet containing vitamin D3 at 1,500 IU/kg and 25OHD3 at 1,500 IU/kg. The dietary intervention from 61 weeks of age to