Effects of supplemental dietary phytase and 25-hydroxycholecalciferol on the performance characteristics of commercial layers inoculated before or at the onset of lay with the F-strain of Mycoplasma gallisepticum.

The effects of dietary supplementation with phytase and 25-hydroxycholecalciferol on the performance characteristics of commercial layers that were inoculated prelay (12 wk of age) or at the onset of lay (22 wk of age) with F-strain Mycoplasma gallisepticum were assessed. Experimental layer diets, which included a basal control diet or the same diet supplemented with 0.025% phytase and 25-hydroxycholecalciferol, were fed from 20 through 58 wk of age. Weekly and total egg production were determined from 22 through 58 wk, and egg weight and various internal egg and eggshell quality characteristics were examined at 34, 50, and 58 wk of age. F-strain M. gallisepticum inoculation decreased egg production at the beginning of lay (wk 22 and 23) but increased post-peak lay at wk 45. However, there were no treatment effects of any kind on total egg production, egg weight, or any of the internal egg and eggshell characteristics examined during lay. In conclusion, dietary supplementation with phytase and 25-hydroxycholecalciferol did not affect layer performance or interact with the effects of F-strain M. gallisepticum inoculation; however, F-strain M. gallisepticum inoculation resulted in a shift in egg production from wk 22 to 45 without having an overall effect on total egg production.