PHYSIOLOGICAL AND BEHAVIORAL HEAT TOLERANCE TRAITS IN INDIGENOUS AND EXOTIC CHICKENS IN SOUTHERN NIGERIA

The research was carried out to study the physiological traits among local chickens by determining the effect of genotype on the rectal temperature, pulse rate and respiratory rate. A total of two hundred and fifty (250) chickens were used for this study. These consisted of 50 birds each of normal feather, naked neck and frizzled matured chicken’s genotypes. Under natural heat stress environment genotype were significantly (P<0.05) affected by rectal temperature, pulse rate and respiratory rate. The naked neck had the highest value of rectal temperature, while normal feather recorded the lowest values of 40.09±0.21oC to 41.05±0.08oC beat/min. The highest value for respiratory rate was observed in naked neck strain, while normal feather strain had the least value of (64.80±2.60 to 22.00±149 breath/min). On pulse rate, naked neck feather strain had the highest value and the least value was recorded in normal feather (234.00±17.21to 397.00±19.15) beats/min. Hematological and serum biochemical parameters of chickens were also evaluated. There were significant (P<0.05) differences between the genotypes in the mean values of packed cell volume (PCV) red blood cell (RBC) count, white blood cell (WBC) count, hemoglobin concentration (Hb), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC). However the frizzle was significantly superior in all the parameters examined. Also RBC was significantly (P<0.05) higher in the frizzle (3.18±0.09, 3.32±0.01and2.85±0.15). There were significant (P<0.05) differences between the genotypes in the total protein, albumin, cholesterol, urea, creatinine, full blood count, calcium and phosphorus of the genetic groups. The normal matured chicken genotype however, had the highest significant albumin (1.61±0.03 1.74±0.05, and 1.90±0.07 ml) and a lower creatinine value (0.45±0.11, 0.86±0.08, and 0.44±0.04ml) compared to the other chicken genotypes. It can therefore be concluded that variations in the genetic make-up of the chickens accounted for the observed differences in heat tolerance traits, hematology and serum biochemical. It can therefore be concluded that variations in the genetic make-up of the chickens accounted for the observed differences in physiological traits. The present result showed that genotype can significantly affect the physiological of chickens with respect to blood, rectal temperature pulse rate, and respiratory rate can be used for selection in order to select the best performing genotype for the environment.