Energy and protein metabolism in lactating sows fed two levels of dietary fat

The effect of feeding lactating sows with low (LF) or high (HF) dietary fat level (31 vs. 113 g crude fat per kg DM) was studied. Four sows on each diet were subjected to three balance and respiration experiments in weeks 2-4 of lactation. The contribution of piglet heat production (HE) to overall HE of sow and piglets (measured by indirect calorimetry) was measured by the doubly labelled water (DLW) technique in three piglets per litter. The nitrogen balance of the sow decreased with progress of lactation, with no dietary effect. Milk production, estimated by deuterium oxide (D2O) dilution in DLW enriched piglets, increased (P < 0.001) from 7.69 (week 2) to 10.64 kg/day (week 4). Sow HE was constant throughout lactation (686 kJ/ kg(0.75) per day) in spite of increased feed intake and milk production. Oxidation of protein constituted 13% of HE in both groups, while oxidation of carbohydrates and fat constituted 84% and 2% for LF sows and 80% and 7% for HF sows, respectively. The present study suggests that the dietary treatments did not affect milk production, milk fat content or the energy mobilisation of the sown The maintenance requirement of metabolisable energy (ME) amounted to 482 kJ/kg(0.75) per day. It was concluded that the milk production was limited by the energy supply and that the efficiency for utilisation of dietary ME for milk production increased as lactation progressed. (C) 2004 Elsevier B.V. All rights reserved.