The effect of pen density during rearing on subsequent reproductive performance in gilts

A study involving 109 crossbred gilts of Duroc and Landrace breeding that were reared in equal-sized pens with 8 or 16 pigs/pen was initiated to determine the effects of pen density during rearing on subsequent reproductive and maternal performance. Gilts in pens of eight were allowed 1.06 m2/animal from 30 to 65 kg and 1.25 m2/animal from 65 to 100 kg, whereas those in pens of 16 were allowed only one-half as much floor area per animal. Gilts raised in groups of eight farrowed 1.0 more pigs/litter (P less than .05), and .7 more pigs/litter born alive (P = .15), than gilts reared in groups of 16 pigs/pen. There were no pen-density differences in the number of corpora lutea at 30 d of gestation (P = .33) or in litter birth weight (P = .26). After adjusting by covariance for the number of live pigs at the beginning of the lactation period, gilts from the pen density of 16 had more pigs per litter alive (P less than .01) and heavier litter weights (P less than .05) at 21 d postpartum and higher piglet survival rates to 21 d (P less than .02) than gilts that were reared in the low pen-density of eight pigs/pen. Results of this study indicate that pen density during the growing-finishing period may affect subsequent reproductive and maternal performance of gilts.