Dw. Garton et al., ENVIRONMENTAL-TEMPERATURE AND METABOLIC RATES DURING GESTATION AND LACTATION IN GOLDEN-HAMSTERS (MESOCRICETUS-AURATUS), Physiological zoology, 67(2), 1994, pp. 497-514
We determined the influence of ambient temperature (T-a) on energetic
costs of reproduction by measuring resting metabolic rate (RMR); body
temperature (T-b) measured rectally, and respiratory quotient (RQ) at
six reproductive stages (premating, middle and late gestation, early,
middle, and late lactation) of reproductively active (RA) golden hamst
ers maintained at 24 degrees C (RA-24) and 30 degrees C (RA-30), with
nonreproductive (NR) females as controls. Reproductively active and NR
hamsters consumed more O-2 at 24 degrees C than at 30 degrees C (with
in the zone of thermoneutrality), but only NR females had a lower RQ a
t the lower T-a. Gestation caused significant (P < 0.05) increase in t
he adjusted RMR of RA-30 dams (as compared to the RMR of the NR-30 con
trols), but this effect of gestation was not detected in RA-24 darns.
Lactating hamsters had higher RMR than did NR females at both T-a's. I
n addition, RA-30 darns had lower RQ during gestation and higher T-b d
uring lactation. These results indicate that increased metabolic costs
of gestation are undetectable in golden hamsters maintained below the
rmoneutrality and that RMR is highest midway through the period of lac
tation in females maintained at both 24 degrees C and 30 degrees C.