All measurements were made at d 30, 45, and 105 of gestation. Respiratory quotient (RQ) was calculated to determine
nutrient utilization. Energy retention (intake minus heat production) (MJ/d) was
greatest on d 45 compared to d 30 or d 105 of gestation. The RQ was greater than 1 and highest on d 45
indicating lipogenesis. Leucine flux, appearance from breakdown, and
incorporation into protein were highest on d 45 compared to days
30 or 105 of gestation. However, as a result of the significant increase in
protein breakdown, protein gain was lower for sows on d 45 compared to d 30. Therefore, energy was preferentially stored by these sows on d 45 at the expense of protein.