Abstract
In this study, the effects of 5 graded dietary levels (0.025, 0.05, 0.075, 0.1, and 0.125%) of dimethylglycine (DMG) were studied in laying hens during the late laying period (71-78 wk). Graded doses of DMG from 0.025 to 0.125% in the diet produced quadratic positive (P < 0.05) responses in the laying rate, egg-feed ratio, yolk color, grade follicular weight, and the number of large white follicles and linear positive (P < 0.05) responses in average egg weight, and the number of large white follicles. With 0.1% DMG, the laying rate and egg-feed ratio improved (P < 0.05), and the abdominal fat percentage decreased. Considering the laying performance under the conditions used in this study, the best-fit model for the DMG requirements of laying hens was estimated to range from 0.049 to 0.065% DMG during the late laying period based on a regression analysis. The addition of DMG did not affect the total cholesterol (TCH) and triglyceride (TG) contents in the plasma of laying hens; however, it significantly reduced the abdominal fat rate. DMG may change the course of lipid deposition in laying hens during the late laying period. In conclusion, supplementation with DMG can improve the laying rate and follicles development of laying hens.