Physiological Responses and Changes of Blood and Urine Constituents during Cold Exposure in Sheep

Abstract

The present investigation was performed in a coldenvironment to determine the main substances used for heat production and for gluconeogenesis in sheep which have peculiar nutritional requirement as compared with a monogastric animal.Four clipped sheep were exposed to ambient temperature of 0°Cfor 7 days in the climatic chamber, and their physiological responses, blood and urine constituents were measured during the exposure period.Immediately after the start of the exposure, severe shivering arose from the limbs, extending over the body, and heart rate and heat production were both increased remarkably. These high levels were maintained for 7 days. Water intake and urine volume decreased distinctly but respiration rate only tended to decreased. Body temperature did not exhibit clear change but the diurnal fluctuations were smaller than those at 20°C.The plasma free fatty acid concentration increased rapidly. Blood glucose and blood Pco2 increased a little but not significantly on and after the 4th day of exposure. Blood free amino acids, lactic acid and volatile fatty acids concentrations did not show any clear changes. The daily urinary excretion of ketone bodies decreased slightly but that of nitrogen hardly changed.The present experiment confirmed that the changes observed in the sheep under the cold environment were almost the same as those of reported in human, dog and other monogastric animals.