Buffalo physiology responses to high environmental temperature and consequences for DAP
1992
Chaiyabutr, N.(Chulalongkorn Univ., Bangkok (Thailand). Faculty of Veterinary Science. Dept. of Physiology)
Review of work on buffalo concerning responses of bodily functions to thermoregulation during heat exposure and their effect on the development of draught animal power (DAP) is given. The cutaneous heat loss under thermal stress and during work is discussed in relation to the peculiar vascular architecture and low sweat gland density in buffalo skin which is shown to be suited for conserving but not for dissipating heat. Thermal hyperventilation, the marked evident reaction of buffalo to heat stress, is discussed in relation to the initiation of panting by thermal stimulation of peripheral receptors, and to the control of respiratory activity by deep body temperature during exposure to either solar radiation or in a hot room. Cardio-respiratory responses to thermal stress show different patterns during exposure to solar radiation. The effect of high temperature on changes of turnover of body water, the volume of the blood, the rate of liquid flow from rumen and renal functions of buffalo are discussed. During acute (5h at 41 deg C in hot room) heat exposure of buffalo, changes of total body water and blood volume are different from short term (10 days outdoors, unshaded, max 39 deg C) of heat exposure. Two phases of changes of body fluid to facilitate the evaporative cooling process in short term heat exposure are aparent. Changes in renal electrolyte excretion during heat stress are discussed in relation to alteration of hormonal level and to the acid base status of the blood. The effect of high environmental temperature on the metabolism of plasma constituents is also discussed. Changes of hormones from pituitary gland, thyroid gland and adrenal gland during heat exposure are also noted.
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