Effects of an Antibiotic and Flushing on Performance of Sows with Short Farrowing Intervals

The reproductive efficiency of 249 sows, mated on the first postweaning estrus following a 3-week lactation, was evaluated. Sows were assigned at weaning to one of four factorially arranged treatments as follows: (I) control, fed 2.27 kg feed daily during pregnancy; (II) same as I plus an additional 2.27 kg feed the day following mating; (III) same as I plus 1.0 g chlortetracycline daily from weaning to 15 days postmating; and (IV) same as I plus an additional 2.27 kg feed the day following mating plus 1.0 g chlortetracycline daily from weaning to 15 days postmating. There were no significant differences among the treatments in estrus or mating behavior or breeding efficiencies, but the addition of the antibiotic to the diet seemed to improve conception and farrowing rates. The total number of pigs farrowed was increased (P<.07) by antibiotic, but there were no other significant main effects or interaction effects in the farrowing or weaning comparisons. Breeding, farrowing and weaning efficiencies for the sows, mated on the first postweaning estrus, were comparable to the efficiencies of sows managed on a less intense reproductive system.