Influence of endogenous heat load or cooling on thermoregulation plasticity of hair sheep and meat goats at extreme heat

Objective: To compare the influence of endogenous heat load or cooling on thermoregulation plasticity between hair sheep and meat goats at extreme heat. Design/methodology/approach: Mature ewes and does of contrasting coat color were subject to endogenous heat load from animal activity, heat increment from feeding, and heat dissipation by shower to compare the changes on their core body temperature as a proxy of thermoregulation plasticity at extreme heat. Results: Endogenous heat load from activity increased core body temperature in both treatment groups similarly, however, ewes showed slower heat dissipation response which extended cooling phase time. The heat increment of feeding affected core body temperature greater in ewes than in does within the first postprandial hour with no difference on heat dissipation response thereafter. Cooling by shower increased heat load dissipation and reduced core body temperature similarly in both groups of animals, however, wetting does triggered an increase in the behavior of basking in the sun. Limitations on study/implications: Does lost endogenous heat load from activity faster and had a lower heat increment due to feeding than ewes. Cooling by shower helped keep ewes’ core body temperature lower longer than in does who looked for sunshine to rewarm themselves. Findings/conclusions: Meat goat slightly overperformed to hair sheep on thermoregulation plasticity when challenged with endogenous heat load at extreme heat. Cooling by shower improved the thermal comfort of hair sheep at extreme heat but limited benefits were observed in meat goats. The red coat color did not increase thermal heat gain in meat goats.