277 Management of gilts to maximize lifetime productivity

The objective of this presentation is to review gilt characteristics associated with enhanced lifetime productivity and discuss their possible incorporation into management programs. The last 40 days of gestation is a crucial period of reproductive organ development. As a result, there is a positive relationship between birthweight and adult reproductive performance with most studies reporting decreased removal rates and increased pigs weaned per litter when birthweight was greater than 1.3 kg. Unfortunately, nutritional strategies for improving birthweight have been inconsistent. However, its use as a selection criterion has shown promise for the early removal of sub-fertile gilts. Colostrum contains bioactive compounds that stimulate ovarian and uterine development. Significant positive correlations exist between circulating immunoglobulins in 1-day old gilts and lifetime productivity. Gilts with the highest levels reached puberty 20 days earlier and weaned 1.4 more pigs over four parities compared with those with the lowest levels. Therefore, strategic split-suckling and cross-fostering merit consideration for enhancing colostrum intake. Weaning weight is also positively correlated with sow longevity and several studies have reported that increased pre-weaning growth can partially offset some of the negative consequences of low birthweights. Litter size often exceeds numbers of functional teats for hyper-prolific sows so pre-weaning supplemental feeding programs may prove beneficial in this situation. Porcine follicles require 120 days to reach ovulatory competence which means the cohort of follicles responsible for puberty begins to develop when gilts are 40 to 50 days of age. During this period, nutritional programs designed to produce gilts weighing between 115 and 140 kg at first breeding have received the most attention. In a large commercial system, feeding grower and finisher diets with lysine-to-energy ratios less than 2.8 and 2.1, respectively, delayed puberty and required increased use of P.G.600 to achieve adequate numbers of bred gilts within this weight range. In conclusion, use of birthweight as an early selection criterion, strategies that enhance colostrum consumption and pre-weaning growth, and feeding programs that achieve planned post-weaning growth have potential for enhancing gilt development and maximizing their lifetime productivity.