INFLUENCE OF SOURCE AND LEVEL OF ENERGY AND LEVEL OF PROTEIN INTAKE ON SOW PERFORMANCE DURING GROWTH, GESTATION, AND LACTATION: II. EFFICIENCY OF ENERGY TRANSFER TO THE LITTER

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Abstract
Sixty sows which were fed in five ration groups and which received different sources (no supplemental fat versus 15% stabilized tallow in the ration) and levels of energy and levels of protein were used to evaluate energetic efficiency of the sow in producing pigs to a weaning age of 5 weeks. Twenty per cent energy restriction during growth and eight per cent during reproduction, with or without protein restriction, were compared with energy and protein intakes that met U.S. N.R.C. requirements for growing pigs and for gilts. When adjusted for sow weight gain or loss, the energetic efficiency of sows in producing weanling pigs did not vary significantly between ration groups. The correlation coefficient (r) between energetic efficiency of litter gain and total weight of pigs weaned in the litter was.85. During the first lactation 19.2% and during the second lactation 19.7% of the apparent digestible energy in the feed was used for litter gain. When gestation and lactation were combined, the efficiency of litter gain was 13.1 and 14.6% for the first and second reproductive cycles respectively. An overall efficiency of litter gain of 11.4% was obtained when the energy requirement of gilts for growth was also included. The energetic efficiency of litter gain had a slight negative association with the average daily gain of the sows up to 215 lb liveweight. The r between either number of pigs weaned or the weaning weight of pigs in the litter from which dams were selected and total weight of pigs weaned in a sow’s first two litters was.43.