Fig. 6. Milk energy output (MEO) of 24 female mice at 30°C, determined as the difference between metabolizable energy intake and daily energy expenditure (MEI–DEE), from female water turnover (rH₂O_fem), from pup water turnover (rH₂O_pup) and from litter energy budget (LEB). All estimates of MEO refer to day 14 of lactation. MEO determined from female water turnover was significantly lower than the three other estimates, as denoted by the asterisk (for statistical details, see Results). Bars are means ± 1 S.D.