SHIVERING THERMOGENESIS IN THE NEONATAL PIG

(1) Shivering intensity and metabolic rate were determined in Large Wh ite pigs aged 2, 24, 48 h and 5 d, at temperatures ranging from thermo neutrality (36 degrees C) to cold (20 degrees C). (2) Shivering is the main heat producing mechanism, the absence of nonshivering thermogene sis being implied by both the absence of delay between the onset of sh ivering (S-tt) and the increase in metabolic rate (L(ct)) and by the l inearity of the relationship between metabolic rate and shivering inte nsity in the cold. (3) For a comparable thermal demand, shivering inte nsity decreased with age whereas cold induced heat production remained constant, which suggests that the thermogenic efficiency of shivering is improved during the first 5 days of life.