GASTROINTESTINAL BLOOD FLOW DISTRIBUTION IN COLD-EXPOSED SHEEP

Abstract

The influence of acute and chronic cold exposure on the distribution of cardiac output to the gastrointestinal tract was measured in adult sheep (35–50 kg) using radioactive microspheres containing ¹⁴¹Ce and ¹¹³Sn. Groups of four sheep were exposed in controlled temperature chambers to either (1) control temperature, 18 °C for 10–12 wk; (2) acute cold, exposure to 3 °C for 12 h; (3) chronic cold, exposure to 3 °C for 10–12 wk. In the control, acute cold and chronic cold treatments, respectively, 26.4, 20.5 and 19.4% of cardiac output was distributed to the gastrointestinal tract. The estimated amount of blood flow (mL/100 g wet tissue/min) to the total gastrointestinal tract was not significantly different among the three treatment groups (67 mL/100 g/min for the control versus 62 and 50 mL/100 g/min, respectively, for the acute cold and the chronic cold sheep). However, there was a significant decrease in blood flow to the reticulo-rumen of the acute cold- and chronic cold-exposed sheep (34.0 and 37.8 mL/100 g wet tissue/min for the acute and chronic cold sheep versus 56.0 mL/100 g/min for the control sheep). The redistribution of gastrointestinal blood flow induced by exposure to cold may be a factor in reduced nutrient absorption in cold-exposed ruminants.