Body Surface Evaporation Rates at Low and High Temperatures for Gir and Hariana Cattle

Abstract

Six 18–24 month old, open Hariana heifers and a group of contemporary Gir were used to determine rate of evaporation from the skin surface under 18.5 C dry bulb temperature, 13.0 C wet bulb temperature and 40.5 C dry bulb temperature, 35.0 C wet bulb temperature. The animals were subjected to each of the test conditions in the winter, monsoon and summer seasons. Water on the skin surfaces was measured from shoulder, flank and rump using a capsule technique following 4 hours in the control room. At 18.5 C the evaporation rates in all seasons were low (avg 5.2 mg/10 cm2/5 min) with those in winter being lowest (2.8 mg). In the 40.5 C temperature, rates averaged 57.6 mg, and the variance attributed to breed, season and breed x season interaction were significant (P < .01). Rates for the two breeds were about the same in summer and winter at 40.5 C, but the Hariana had much the higher rates in the monsoon season. Season effects were important in determining the rate under both cool and hot conditions; thus, conditions to which the animals were accustomed prior to the tests influenced evaporation rates. Rates were not influenced by body location. There were significant (P < .01) negative correlations (–.34 to –.45) between evaporation rates and skin temperature in both breeds and with rectal temperature in Girs (–.36). In Hariana, rectal temperature was positively correlated (P < .01) with evaporation rate (+.56). © 1968, American Dairy Science Association. All rights reserved.