The influence of preincubation heating of turkey eggs on mycoplasma infection

Five groups of turkey hatching eggs from two mycoplasma infected flocks were subjected to preincubation heating in an attempt to eliminate mycoplasma, particularly M. meleagridis. The eggs were heated over 11.5 to 12.5 hours with a linear increase in temperature from approximately 25 degrees C to mean maxima ranging from 46.2 degrees C in one trial to 47.6 degrees C in the fifth trial. Both untreated control eggs and preheated eggs were then conventionally incubated and at hatching live poults were killed. Recovery of mycoplasma was attempted from pools of respiratory tract, cloaca and yolk which were made separately from each group. Whilst M. meleagridis was isolated from 13 of the 15 tissue pools of the control poults, it was only recovered from five of the pools from preheated eggs and not from any in the two trials at the higher temperatures. Nevertheless, other mycoplasma were recovered from the two groups at these temperatures but not from all the tissues. At the higher maximum temperatures also there was a very significant reduction in hatchability.