Thermoregulation in humid climate-adapted and Savannah breeds of goats exposed to West African cold (harmattan) season

The West African Dwarf (WAD) goats have hereditary dwarfism and are adapted to the humid climate. The study compared the cold tolerance of WAD and Savannah (Red Sokoto and Sahel) goats during the peak of the West African cold season in the Northern Guinea Savannah of Nigeria. A total of 18 adult non-pregnant, dry does comprising equal number of each breed (six per breed) were used for the study. Thermoregulatory variables were recorded four times in the morning (07:00 h) and afternoon (13:00 h) hours at two-day intervals. Results revealed that irrespective of the hour of day, the WAD had significantly (p < 0.05) higher respiratory rate when compared with Red Sokoto and Sahel goats. The diurnal afternoon rise in respiratory rate and the magnitude of afternoon rise in rectal temperature was higher (p < 0.0001) in WAD than Sahel and Red Sokoto goats. The body surface temperature in the morning hours was significantly lower in WAD compared with Sahel breed, while in the afternoon hours, the inter-digital space temperature was significantly lower in WAD compared with Savannah breeds. However, there were no significant (p > 0.05) differences in heart rate, rectal, head and leg temperatures between the breeds in both morning and afternoon hours. Discriminant analysis revealed that the morning hours induced greater homogeneity in the thermoregulatory responses between the breeds adapted to the humid and Savannah climates as compared with the afternoon hours. It was concluded that although WAD goats employed more intense peripheral vasoconstriction to survive cold exposure and demonstrated greater diurnal amplitude in thermoregulatory variables, they maintained comparable core body temperature as the indigenous Savannah breeds. Thus, suggesting that despite the hereditary dwarfism, the WAD goats could conserve body heat during the West African cold season in the Northern Guinea Savannah zone of Nigeria.