Variation in Volume and Composition of Body Fluids (Interstitial, Blood and Urine) as a Measure of Adaptability in Buffaloes to a Hot Environment

Abstract

SUMMARY The adaptability of the buffalo for tropical climates was assessed. Three factors, the extracellular fluid and blood volume, the serum molecular and electrolyte concentration, and the electrolyte and total molecular excretion in urine, were investigated in animals protected from, or exposed to, the adverse climatic conditions of the summer season. The protected animals were kept in an artificially cooled shed (AP animals), while the exposed animals were conventionally managed (CM animals). Values for plasma, interstitial and extracellular fluid volume were higher in the CM than the AP animals. These changes indicate directions and capacity for adjustment of buffaloes to hot climates. The increased molecular concentration of serum—particularly sodium and chlorine—was important in increasing the extracellular fluid content of the body. The osmotic concentration of serum was not altered markedly and the increase in the fluid content can rightly be considered as “isotonic expansion”. The observed retention of sodium and chlorine by the kidney tended to increase the serum concentration. This in turn appeared to bring into play the osmoreceptor of the body which regulates ADH secretion. The retention of water so effected brings about expansion of extracellular space.