Anticoccodial protection and development of immunity to turkey coccidiosis while using monensin.

Monensin at 60, 80 or 100 ppm provided sufficient early protection against coccidiosis in floor-pens seeded with a mixture of Eimeria adenoeides, E. gallopavonis and E. meleagrimitis oocysts to prevent mortality due to coccidiosis and permit satisfactory weight gains. Unmedicated poults suffered 7% mortality and significantly (P</= 0.05) reduced weight gains compared with medicated birds. No mortality occurred after medication was withdrawn at 10 weeks of age. In poults fed monensin at concentrations of 60, 80 and 100 ppm immunity development was sufficient to prevent mortality and weight loss in challenged poults. Some delay in development of immunity in birds medicated at 80 or 100 ppm was indicated by comparing lesion scores with those of unmedicated poults. Greater immunity occurred in all floor-pen reared groups (medicated or unmedicated) when compared with battery-reared, susceptible controls of the same age. Development of immunity, measured by lesion scores, occurred less rapidly in the caecal regions than in the upper intestine suggesting that E. meleagrimitis (upper intestine) may be more immunogenic than the other two species which largely parasitise the caecum.