Influence of supplemental dietary poultry fat on the digestive and reproductive organ characteristics of commercial layers inoculated before or at the onset of lay with F-strain Mycoplasma gallisepticum.

Effects of F-strain Mycoplasma gallisepticum (FMG) inoculation and 1.5% supplemental dietary poultry fat (PF) on the digestive and reproductive organ characteristics of commercial layers at 58 wk of age were investigated. Sham and FMG inoculations were administered at 12 (before lay) and 22 (early in lay) wk of age, and dietary treatments (basal control diets and basal control diets with PF) were initiated at 20 wk of age. Supplemental PF increased BW and decreased isthmal length relative to total oviduct length in hens. Various oviduct segments were also affected by the type and age of inoculation, and these effects were further influenced by the use of PF. In comparison to their time-specific sham-inoculated controls, infundibulum weight relative to BW was increased when birds were inoculated with FMG at 22 wk, whereas isthmus weight relative to total oviduct weight was increased by FMG inoculation at 12 wk of age. However, PF affected infundibulum length relative to total oviduct length only in sham-inoculated birds, and PF increased magnum weight relative to total oviduct weight only in birds inoculated at 22 wk of age (sham or FMG). Furthermore, PF decreased isthmus weight relative to total oviduct weight only in birds that were sham-inoculated (12 or 22 wk). In conclusion, the inoculation of FMG at 12 or 22 wk may increase the relative contributions of the isthmus and infundibulum, respectively, to the total mass of the oviduct. In addition, PF may decrease the relative length of the isthmus and increase the relative weight of the magnum in the oviducts of birds that have been inoculated at 22 wk of age (sham or FMG). Previous studies have shown 1.5% supplemental dietary PF to influence feed consumption throughout lay and performance early in lay in hens that were inoculated with FMG at 12 wk of age. However, the current results suggest that these influences are associated with gross changes in the oviduct but not the digestive tract of layers.