|Peebles, E - MISSISSIPPI STATE UNIV|
|Burnham, M - MISSISSIPPI STATE UNIV|
|Whitmarsh, S - MISSISSIPPI STATE UNIV|
|Gerard, P - MISSISSIPPI STATE UNIV|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 11, 2007
Publication Date: March 10, 2008
Citation: Peebles, E.D., Branton, S.L., Burnham, M.R., Whitmarsh, S.K., Gerard, P.D. 2008. 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 . Poultry Science. 87:598-601. Interpretive Summary: Mycoplasma gallisepticum (MG) is a bacterial pathogen which is endemic throughout the table egg sector of the poultry industry. It is associated with losses approximating 16 eggs per hen over a 45 week laying cycle. These egg losses alone are estimated to cost the industry approximately $140 million annually. Efforts to stem the losses include the use of vaccines; however, none of the three currently available live MG vaccines are ideal although each has specific strengths and weaknesses. The purpose of the present study was to determine if a combination of the supplemental dietary enzyme phytase and 25-hydroxycholecalciferol (25-vitamin D3) might help to alleviate the negative impact on early egg production of the F strain MG vaccine, Results of this study showed a decrease in egg production at the beginning of lay (wk 22 and 23) but increased lay at post-peak (wk 45). Overall, there were no negative effects on total egg production, egg weight or other egg or eggshell characteristics.
Technical Abstract: 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 postpeak 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 Fstrain 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.