Responses of pregnant ewes and young lambs to cold exposure.

The effects of cold stress were studied in pregnant ewes during the last three weeks of gestation and in their progeny during the first three days of life. In general, ewes were unaffected by treatment whereas changes were observed in the cold-stressed lambs. Cold-induced changes in lambs included physical weakness, depression, and poor nursing response. Serum concentrations of glucose and insulin were lowered whereas concentrations of blood urea nitrogen, alkaline phosphatase, aspartate aminotransferase, lactate dehydrogenase, triglycerides, and cortisol tended to be higher in cold exposed lambs. The mortality rate was higher (40%) in cold-stressed lambs than in lambs kept at warmer temperatures (10%). At necropsy, cold-exposed lambs had reduced amounts of adipose tissue in perirenal areas, and extensive subcutaneous hemorrhages and edema in the distal portions of the thoracic and pelvic limbs.