Body temperature of huddling newborn Zucker rats

Daily mean core temperature (\(\bar T_c \)) in huddling Zucker rat pups reared at 25°C revealed the onset of a significantly lower\(\bar T_c \) in fa/fa pups on day 6. The difference between any pup's\(\bar T_c \) and the mean\(\bar T_c \) of that half of the litter with the highest\(\bar T_c \) on any given day was an early marker for genotype. Calculating the mean difference for any 2 consecutive days from day 6 onwards gave values for each fa/fa pup that were outside the 99% confidence limits for the individual observations in the Fa/-pups.