The addition of ground wheat straw as a fiber source in the gestation diet of sows and the effect on sow and litter performance for three successive parities.

A regional experiment was conducted at 8 experiment stations, with a total of 320 sows initially, to evaluate the efficacy of adding 13.35% ground wheat straw to a corn-soybean meal gestation diet for 3 successive gestation-lactation (reproductive) cycles compared with sows fed a control diet without straw. A total of 708 litters were farrowed over 3 reproductive cycles. The basal gestation diet intake averaged 1.95 kg daily for both treatments, plus 0.30 kg of straw daily for sows fed the diet containing ground wheat straw (total intake of 2.25 kg/d). During lactation, all sows on both gestation treatments were fed ad libitum the standard lactation diet used at each station. Response criteria were sow farrowing and rebreeding percentages, culling factors and culling rate, weaning-to-estrus interval, sow BW and backfat measurements at several time points, and litter size and total litter weight at birth and weaning. Averaged over 3 reproductive cycles, sows fed the diet containing wheat straw farrowed and weaned 0.51 more pigs per litter (P <or= 0.04), and had total litter birth and weaning weights that were 0.87 and 3.59 kg heavier (P = 0.01), respectively, than sows fed the control gestation diet. Sows fed the gestation diet containing wheat straw consumed more (P = 0.01) lactation diet per day than control sows. There were no gestation diet treatment differences for any sow fate criterion (farrowing and rebreeding percentages, and culling rate), any sow BW and backfat measurement, or the weaning-to-estrus interval. Lactation diet intake and all sow BW and backfat measurements increased with increasing parity. In conclusion, when the daily intake of the basal gestation diet was equalized for both treatments, the addition of 13.35% ground wheat straw to the gestation diet improved sow and litter performance, with increases in litter size and total litter weight at birth and weaning compared with control sows and litters.