Response of 2 breeds of broiler chicks to experimental infection with low dose of Eimeria tenella sporulated oocysts

This study evaluated the effect of low-grade Eimeria tenella infections in broiler chicks of Cobb (C) and Marshal (M) breeds. Birds from the experimental group of each breed were orally infected with 3000 sporulated oocysts of E. tenella and examined for weight gain, feed conversion ratio (FCR), packed cell volume (PCV), total leukocyte count (WBC), total plasma protein (TP), gross lesion scores, and histopathological changes 10 days after infection. There were 31.7% and 15.7% reductions in the mean weight gain of experimental groups of C and M, respectively, compared to their controls; this was statistically significant (P 0.05) in M. Differences in FCR values between infected and control groups were 0.4 and 0.04 in C and M, respectively. There were no significant differences (P > 0.05) between the mean PCV and WBC values of the infected and control groups in either breed, but the mean TP values were significantly lower (P < 0.05) in the experimental groups of both breeds. Mean gross lesion scores were significantly higher in C than in M (P < 0.05) but the histopathological changes observed were similar in both breeds.