Aspects of the Performance of Broiler Chickens Infected at Different Ages with Two Field Strains of <em>E Maxima</em>

Abstract

The effects of infections by two field isolates of E. maxima (isolates B and L) on four different ages of broiler chickens were not significant (p>0.05). Broiler chickens inoculated at 2 weeks or 4 weeks of age with two isolates of E. maxima showed evidence of significant growth depression at 5 days post inoculation (pi); whereas, those inoculated at 4 days or at 6 weeks of age did not show signs until 7 days pi. Weight depression, was more marked in broilers inoculated at 2 weeks or 4 weeks of age than those inoculated at 4 days of age. The depressed growth rate curve of the uninfected control at 6 weeks was because of the size of the birds visa verse the battery cage used for the experiment by the time the birds were 7 and 8 weeks old. In all the ages of birds used in this experiment, the feed efficiencies calculated from D to D+35 pi in birds that received isolates B and L were significantly poorer (p<0.05) than that of the uninfected controls. However, differences between isolates L and B infected birds were not significant (p>0.05).

Keywords: infection, field isolates, E. maxima, performance, broiler chickens