Fig. 8. Milk energy output (MEO) determined from litter energy budget of female mice at 30°C (N=67) as a function of litter size. Both MEO and litter size are those on day 14 of lactation. Females with six pups exported more energy in milk than those with 1–3 pups. For litter sizes of 6–15, no further increase in MEO was observed (for statistical details, see Results).