S41 Effects of F-strain Mycoplasma Gallisepticum. Inoculation at Twelve Weeks of Age and Diet Supplementation on the Performance and Egg Char- Acteristics of Commercial Layers

The effects of a 12 wk F-strain Mycoplasma gallisepticum (FMG) inoculation and various dietary supplementation regimens on performance and egg characteristics in Hy-Line W36 hens between 22 and 52 wk were investigated. At 12 wk of age, 120 sham (control) and 120 FMG(treated) inoculated birds were randomly assigned to individual cages in one of two enclosed and isolated ends of a caged layer facility according to inoculation treatment. One of four isocaloric diets was randomly provided to birds in each end at 20 wk of age. Diets included 1) normal basal diet (NB); 2) NB with 1.25% additional poultry fat (PF); 3) NB with 2.00 % additional PF; and 4) NB with 2.00% additional PF and supplemental phytase and 25-hydroxyvitamin D3. Inoculation type and diet treatment combinations were thrice replicated, with ten hens in each replicate group. Parameters investigated were BW, mortality, feed consumption, egg production (EP), egg weight (EW), percentage eggshell (PSW), yolk (PYW), and albumen (PAW) weights, eggshell weight per unit of surface area (SWUSA), and yolk/albumen ration (YAR). Only age effects were noted for all egg characteristic parameters. Supplemental phytase and D3 slowed the increase in BW in FMG-treated birds, and EP decreased more rapidly in sham inoculated controls when fed either 1.25 or 2.00% supplemental PF. FMG-inoculation accelerated the decrease in EP in birds fed the unsupplemented NB diet; however, 1.25 % added PF helped to reverse this effect. Supplemental PF at the 1.25% level may improve EP in commercial layers inoculated with FMG at 12 wk of age.