EFFECTS OF INGESTION OF WARM, COLD AND FROZEN WATER ON HEAT BALANCE IN CATTLE

Abstract

Four steers were used in a 4 × 4 latin-square-designed study that consisted of four 14-day periods and four water treatments. Once daily for 30 min, the steers were offered either snow, crushed ice, cold water (CW) near 0 °C or warm water (WW near 30 °C. These restricted water sources were offered 18 h after feeding to maximize possible thermal stress due to ingestion of the cold or frozen water. The snow and ice treatments reduced water intakes, rumen volume and dry matter of rumen contents. The maximum increment in metabolic heat production was observed with the ice treatment, 278% of preingestion metabolic rate, and this treatment also elevated metabolic rate for the longest time (182.5 min). The total increment in heat production by the steers was approximately 50% of the heat energy required to melt the snow or ice and raise the resultant water to body temperature. Minimal rumen temperatures were observed earlier than minimal rectal temperatures with the ice treatment resulting in the largest decrease in both rumen (16.5 °C) and rectal (1.4 °C) temperature. When offered choices of pairs of all combinations of snow, ice, CW and WW, the steers showed no preference for either the CW or WW. They preferred liquid water but would consume snow or ice when no liquid water was available. It was concluded that steers can tolerate thermal stress resulting from rapid ingestion of snow and ice drawing approximately equally from body heat and from increased metabolic heat production to compensate for the latent heat and heat of warming water. Key words: Cold water, heat balance, thermal stress, cattle, snow