Genetic and phenotypic correlations among coccidiosis-tolerant traits in Nigerian indigenous chickens

Abstract

Poultry meat is mostly consumed by Nigerians because of its low fat content. However, coccidiosis Eimeria poses a serious threat to the livestock industry. The identification and understanding of the association of genes encoding traits that can affect the outcome of the disease can then be applied to increase their frequency in a population through selective breeding. A total of 143 birds of three genotypes of Nigerian indigenous chickens which included Normal feather, Naked neck and Frizzle feather were used for the experiment. Body weight gain (WG), lesion score (LS), feacal oocysts count (FOC) and some haematological parameters which included RBC (Red Blood Cell), WBC (White Blood Cell), LYMPH (Lymphocytes), NEUT (Neutrophils), BAS (Basophils), MON (Monocytes) and EOS (Eosinophil) of control and inoculated birds (with Eimeria tenella) were estimated by nested analysis of variance procedure of SAS to derive paternal half-sib estimate of variance and covariance components used to estimate heritability, genetic and phenotypic correlations (h², rg and rp respectively) between all pairs of traits. The h² increased moderately in haematological traits with EOS having the highest value (0.88 ± 0.03) followed by WBC (0.75 ± 0.15). The highest h² was observed in WG (0.95 ± 0.21). The rg was high for WBC pairs of traits and the highest rg was observed in WBC/LS (0.96 ± 0.31) suggesting that the level of WBC can affect the severity of the infection as indicated by the LS level. The rp was high for WBC-correlated traits which are in agreement with their high rg with the highest being WBC/LYMPH (0.91 ± 0.30), which suggested that the susceptibility of birds changes in relation to the prevalence of these cells.