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For the first gestation and lactation period, gilts had increased (P < 0.001) backfat thickness on d 35, 90, and 112 of gestation and at farrowing compared with sows but had increased (P < 0.001) lactation backfat loss. Increasing late gestation feed increased (P < 0.001) weight gain from d 90 to 112 in both gilts and sows. There were late gestation feeding level x parity interactions observed (P < 0.04) for ADFI and total feed intake for the overall lactation period. This was due to gilts having decreased lactation ADFI when fed extra feed in late gestation, but when sows were fed extra feed, lactation ADFI increased. Increasing feeding level in late gestation also increased (P < 0.04) total feed cost. A feeding level x parity interaction was observed (P < 0.04) for average weight of total born and live born pigs. Increasing feeding level in late gestation increased piglet birth weight in gilts but decreased piglet weight in sows. Gilts had increased (P < 0.02) number and total weight of the total born, live born, and number after fostering compared with older parity sows. Gilts weaned larger (P < 0.002) litters and had increased (P < 0.03) total litter weaning weight compared with older parity sows. At weaning, sows had a decreased (P < 0.002) weaning to breeding interval compared with gilts, and a late gestation feeding level x parity interaction was observed (P < 0.03) for conception rate. During the subsequent lactation period, a feeding level x parity interaction was detected (P < 0.005) for lactation backfat loss. A feeding level x parity interaction was detected (P < 0.02) for lactation weight loss. Total born and live born numbers and total litter weight were greater (P < 0.006) in parity 2 sows than in parity 3 and older sows. Additional feed in late gestation increased (P < 0.02) average piglet weaning weight, with a large improvement observed in parity 2 sows.
It is concluded that adding extra feed to late gestation diets increased feed cost with no benefit in sow performance. In gilts, conception rate and litter weaning weight were increased during the second parity, but no other benefits were found.
NW Shelton, JM DeRouchey, CR Neill, MD Tokach, SS Dritz, RD Goodband, and JL Nelssen. 2009. Swine Day, Kansas State Univerity: 38-50.
