Effects of different infection rates on the oocyst production ofEimeria acervulinaorEimeria tenellain the chicken

Abstract

Experiments using chicks of specified strain, age and sex raised under identical conditions on the same diet and infected with known strains of coccidia are described. The relationships between the infection rates and resulting oocyst productions ofEimeria acervulinaandE. tenellaare presented graphically and are used to demonstrate a crowding effect. Possible contributory factors to the crowding effect and possible reasons for the differences between theE. acervulinaoocyst production of unmedicated birds or birds medicated with decoquinate are discussed. It is suggested that standard curves for normal infection rate — reproductive potential relationships under strictly specified conditions may be of value in choosing appropriate infection rates for critical experimental work to assess the effects of anticoccidial compounds on oocyst production.