Genetic differences in the body weight and haematological traits of Nigerian indigenous chickens infected with Eimeria tenella.

In an effort to shed more light on the tolerance of indigenous chickens to coccidiosis, we compared the body weight, faecal oocyst load and haematological parameters based on sex and genotypes of Eimeria tenella-infected chickens. Three hundred chicks from three genotypes (normal-feathered, frizzle-feathered and naked-neck) of Nigerian indigenous chickens which comprised 100 birds per genotype were raised for 6 weeks. At 3 weeks old, each chick was weighed and faecal, and blood samples were collected before inoculation. Subsequently, the birds were weighed and faecal samples collected at days 1, 3, 6, 9, 12 and 15 post-inoculation. Blood samples were collected from 50 chicks per genotype at 3 and 5 weeks post-inoculation. Blood parameters were determined and faecal samples subjected to McMaster egg counting technique. Results showed genotype, and sex had significant effects on body weight from day 1 to 15 post-inoculation. Normal-feathered chicks had the highest body weight while frizzle-feathered chicks showed lowest body weight at post-inoculation. E. tenella was identified in caecal and lower intestinal mucosa of the genotypes, but genotype had no significant effect (p > 0.05) on the lesion score. There were no significant differences in haematological values among genotypes (p > 0.05) except for lymphocytes where naked-neck chicks had the highest lymphocytes' count (1.83 ± 0.02 %), followed by normal-feathered (1.79 ± 0.02 %) and the frizzle-feathered (1.68 ± 0.02 %). The present values of body weight, faecal oocyst and haematological parameters obtained seemed not to be convincing enough to suggest that the genotypes were different in terms of tolerance to coccidiosis.