The utilization of lactic acid by sheep in late pregnancy

The irreversible loss of lactate and the respiratory exchange in four conscious ewes that were about 138 days pregnant were measured at least seven days after surgery. In addition, the uptake and net output of lactate and the net uptake of glucose and alanine by the gravid uterus and an upper hind limb (primarily skeletal muscle) were measured. Calculated heat production of the ewes was 496 kJ/d.kg 3/4; irreversible loss of lactate was 9.5 mumol/min.kg of which 73% was oxidized to CO2, contributing 9% to the ewes' CO2 production. About 2% of the glucose and 65% of the alanine was derived from lactate. Lactate was taken up by both the gravid uterus and the upper hind limb; output of lactate could have accounted for from 8-12% of glucose uptake by the gravid uterus but from 35-50% of that by the upper hind limb. The carbohydrate/O2 quotient was 1.07 for the gravid uterus and 0.35 for the upper hind limb.