The successful introduction and retention of gilts and sows through the early parities drives lifetime performance of the breeding herd and represents an opportunity to improve and enhance overall production. Nearly 20 percent of culling of females from the breeding herd occurs before they produce a second litter!

Key risk factors for sow longevity are best addressed in a designated Gilt Development Unit (GDU), by maintaining a constant input of high quality gilts.

Gilts should be recorded in standing heat within a defined number of days after starting effective boar stimulation and are considered “Select” gilts: All other gilts are considered “opportunity” females and only entered into the herd if breeding targets cannot be met from the “Select” gilt pool. Finally, gilts must have sufficient body condition (135 to 150 kg of body weight) and sexual maturity (at least second estrus) when bred to optimize sow lifetime performance.

Excellent lifetime performance of sows is achievable with attention to good management practices. The need to develop management techniques that reflect the changing biology of contemporary dam-line females is an issue. In our recent studies with first parity sows made seriously catabolic in late lactation, early emergence of pre-ovulatory follicles after weaning, and the lack of an effect on WEI and ovulation rate, were nevertheless associated with pregnancy rates at d 30 of gestation of between 90 and 100 percent!

Maximizing feed intake and providing good daily boar stimulation between weaning and breeding, and use of well-characterized boars for AI use, undoubtedly contribute to these high pregnancy rates. Consequently, the key question that should drive the development of future management strategies in contemporary weaned sows will be a cost-benefit analysis of the trade-off between high pregnancy rates and minimal NPD after weaning, compared to the cost of extra NPD incurred by delaying post-weaning estrus but the benefits of improving the number and quality of pigs born.