Heat and Vapor Production of Dairy Heifers and Sheep PDF

Keywords

sheep, heifers, feed utilization

Abstract

Seven experiments in total with three replicates per experiment were conducted to determine the heat and moisture produced and efficiency of feed utilization for growing dairy heifers and sheep under actual production conditions. Total heat production for dairy heifers was linearly decreased from 278 to 152 Watt/100 kg as they grew from 98 to 305 kg. The decrease of total heat produced for sheep, on the other hand, was from 10 to 4.3 Watt/kg as they grew from 20 to 53 kg. Heat loss by evaporation represented an average of 37% and 68% of the total heat produced by heifers and sheep respectively. Linear regression equations were developed to predict the heat losses as function of animal body weight. The effect of body covering or fleece thickness on sheep heat losses were also studied. The percent of sensible heat loss to the total heat loss increased from 14% to 52% as fleece were sheared from 9 to 0.4 cm. Growth rate and feed efficiency were also determined. The feed efficiency decreased from 0.41 to 0.11 as heifers grew from 98 to 305 kg, while the drop was from 0.33 to 0.16 as sheep grew from 20 to 53 kg.