Heat Tolerance Attributes of Nigerian Locally Adapted Chickens as Affected by Strain and Some Qualitative Traits

This study was undertaken to determine the heat tolerance attributes of Nigerian locally adapted chicken as affected by strain and some qualitative traits. The experimental birds consisted of four matured strains. A total number of 120 healthy matured birds consist of30 each of Naked Neck, Normal Feather, Fulani and Frizzle feather. Each bird was monitored and measured for the number of comb cups, comb length, comb height, wattle height and width at the beginning of the experiment and recorded for each strain. Data were obtained on a daily basis (afternoon) for 12 weeks. The measurement taken include: Numbers of comb cups, Comb length, Comb height, Wattle height, and Wattle width. The heat tolerance attributes considered were the rectal temperature, pulse rate and respiratory rate. Chicken strain and sex had significant effect (P<0.05) on pulse and respiratory rates. The lowest heat stress index, pulse and respiratory occurred in the naked neck with corresponding values of 0.84, 42.65beats/min and 40.26breath/min. Female birds had higher physiological values. Comb length and height differed significantly (P<0.05) with pulse and respiratory rates while no significant (P>0.05) effect was shown in rectal temperature. Comb cups also affected (P < 0.05) pulse and respiratory rates. The lowest pulse rates were obtained in chicken with measuring 5cm high and 4cm long. Regarding respiratory rate and heat stress index, the lowest values were recorded in chicken having combs that measured 8cm high 7cm long. Th