Lambs lose body heat very rapidly if wet, not sheltered and have not nursed. Starvation, mis-mothering and exposure are by far the commonest causes of death in newborn lambs. If the ewe doesn't have enough colostrum give 2-4 ozs colostrum from another ewe, a cow or a goat. If the lamb's temperature is below 100F, warm with warm air and tube with colostrum. Hypoglycemic lambs will not nurse.
Colostrum substitutes .
Goat colostrum from CAE free goats may be used. Do not feed cow colostrum after 36 hours because of the danger of developing immune mediated anemia. Some cows have antibodies in their colostrum against sheep red blood cells. Dull, won't suck, salivates, rattles when shaken because of gas in the gut, die within 24 hours. Often have low temperature and low blood sugar, so need to differentiate from starvation hypothermia.