Published online by Cambridge University Press: 27 March 2009
1. The rectal temperature of piglets was determined (a) at intervals from birth up to 18 days, (b) at the same time daily until the piglets appeared to be fully thermoregulated.
2. The rectal temperature of a vigorous piglet during parturition may be as high as 104–105° F.
3. During the first few minutes after birth the temperature falls to about 100° F., partly as a result of the lower temperature of the external environment and partly as a result of rapid evaporation of amniotic fluid with which the young pig is covered. The fall in temperature is greater with lighter pigs than with heavier pigs.
4. The temperature falls until the young pig finds its way round to the teats and starts to suckle. This struggle and activity of suckling together with the warmth in the sow's nest causes a temporary rise in temperature. During the first rest the temperature falls again to about 100° F., but vigorous pigs have a normal temperature within 12 hr.
5. Piglets deprived of milk after 5 hr. and 16 hr. suckling experienced a more or less steady fall in temperature to about 98° F. in 2–3 days, when the pigs were comatose and were killed. In the case of a pig which had suckled for 7–8 days the temperature remained more or less normal for 2 days and then declined to 95° F. during 5–6 days. The length of survival depends largely on the initial weight, i.e. on the reserves accummulated during the suckling period, and possibly on the thickness of the insulating layer of subcutaneous fat.