Date of this Version
Gilts of two genetic lines were developed with either ad libitum access to feed or energy restriction (75% of ad libitum) to determine effects on subsequent sow performance and longevity. Gilts can be developed with regimens in which energy is restricted during the growing period but the proportion that express pubertal estrus may be reduced in leaner, faster growing lines. Effects on subsequent farrowing rates are small. Sow weight and buckfat at farrowing and weaning of Parity 1 litters affect the likelihood of producing a Parity 2 litter, but these effects are dependent on lean growth rate of the line and on the gilt development regimen. Weight was important in the slower growing, fatter line developed with the restricted feeding regimen; backfat was important in the leaner, faster growing line, but the effect was twice as great in females developed with restricted feeding than for those developed with ad libitum access to feed.