Use of discriminant analysis for the evaluation of coccidiosis resistance parameters in chickens raised in hot humid tropical environment.

Coccidiosis endemicity remains a major challenge in poultry production in the tropics and all over the world. In order to develop predictive tool for identification of chickens that are at risk of coccidiosis among Nigerian indigenous chickens, body weight gain (BWG) and hematological variables were determined for chickens infected with Eimeria tenella (female = 60, male = 63) and uninfected (female = 51, male = 45). The hematological variables analyzed include the following: packed cell volume (PCV, %), white blood cells (WBC, × 106/μl), and red blood cells (RBC, × 106/μl), as well as differential leucocyte percentages of neutrophils, lymphocytes, monocytes, and eosinophils. Body weight gain was determined at days 3, 6, 9, 12, and 15. Of the 12 variables analyzed, BWG at day 3, monocyte, PCV, and WBC in males and BWG at days 6, 9, and 12, PCV, and WBC in female chickens showed significant (P ≤ 0.01) difference between the infected and uninfected. Stepwise discriminant analysis evolved a model that could distinguish uninfected from Eimeria-infected chickens. Packed cell volume, WBC, BWG at day 3, and lymphocytes emerged the most discriminant between uninfected and Eimeria-infected chickens in male chickens. In female chickens, PCV, RBC, and BWG at day 3 were identified as most discriminant variables in separating the uninfected from Eimeria-infected chickens. Therefore, this study suggests that routine blood test and estimates of body weight gain could serve as a useful tool for identifying chickens that may be at risk of coccidiosis, enabling improvement of preventive measures.