GESTATION ENERGY AND REPRODUCTION IN SOWS OVER FOUR PARITIES

Abstract

One hundred and eighty-seven gilts that conceived at first, second or third estrus after 140 d of age and that had a litter at 21 d post-farrow were fed three gestation energy levels 22.2, 29.2 and 36.2 MJ DE d⁻¹ for four parities to assess the effect of gestation energy level on reproductive performance and longevity. All sows were fed the same lactation diet to appetite twice per day. Gestation energy level did not have a consistent effect on the number of piglets per litter. There was a small linear increase in piglet birth weight as gestation energy level increased. However, piglets from sows fed the medium level of energy were heaviest at 21 d. Weight and backfat thickness of sows tended to change with the level of food intake. Sows that ate more in gestation tended to eat less in lactation. There were significantly fewer sows fed the low gestation energy level completing parities three and four and this was the major factor accounting for fewer total piglets at 21 d post-farrow. Many of the sows not completing the trial on this treatment had 10 mm or less P2 backfat. The major reason for sow removal was due to sows not pregnant at the expected time of farrowing. Estimates were made of feed and energy intake during gestation and lactation consistent with good reproductive performance. Key words: Pigs, reproduction, energy, longevity