Comparative study of adaptation in three chicken genotypes under humid tropical conditions of Nigeria.

Adaptation of Nigerian indigenous chickens (NIC), FUNAAB-α (F-α) and Transylvanian naked neck chickens (TNN) raised during hot-dry season under humid tropical environment was compared during a 4-week period. A well-adapted NIC (n = 12; 6 males and 6 females), a newly developed F-α (n = 12; 6 male and 6 females) and a newly introduced TNN (n = 12; 6 male and 6 females) chickens aged 36 weeks were used for this experiment. Heart rate (HR), respiratory rate (RR), rectal temperature (RT) and skin temperature on comb (COM), wattle (WAT), breast (BRE) and under wings (WIN) were monitored between 13.00 and 14.00h twice a week for four weeks. Wattle temperature (p = .017) and BRE (p = .000) differ significantly among the genotypes. Transylvanian naked neck chickens recorded higher WAT than NIC, though not different from F-α. Nigerian indigenous chickens had lower BRE temperature than other two genotypes. Significantly higher WAT (p < .001) and WIN (p < .05) were recorded in cocks than in laying hens. In contrast, laying hens had significantly (p < .001) higher RR and HSI than cocks. There was interactive (p < .05) effect of sex and genotype on BRE. Nigerian indigenous cocks and hens exhibited lower BRE than others, except F-α cock. There were positive significant correlations between WIN and WAT in the three genotypes. In NIC, COM had positive correlation with WAT (r = .532) and WIN (r = .696). Heart rate was positively correlated with WAT (r = .608) and WIN (r = .697) in F-α, and WIN (r = .512) in TNN chickens. In conclusion, the three genotypes can adequately adapt to the prevailing conditions of humid tropics. Reduction of feather on the neck and breast and higher heat loss capacity in TNN chickens could help the birds adapt to hot-humid environment. The two sexes could adapt to the tropical region. Cocks lose body heat predominantly via non-evaporative means while hens employ evaporative heat loss mechanism.