Materials and methods
The study was peer reviewed and approved by the Bioniche Animal Care and Use Committee. This trial was performed under field conditions at an 800 sow commercial farrow to wean unit. All sows were housed in individual crates. Sows were fed twice daily and water was available ad libitum. A veterinarian selected the farm on the basis that knowledgeable staff, with excellent animal-husbandry and recordkeeping skills, were employed, and high levels of sow productivity were routinely achieved. This study was conducted on 14 weanedsow groups between August and October,
2007. Sows were weaned on consecutive Mondays and Thursdays. At the time ofweaning, after a 21-day lactation, a total of 344 sows were randomly assigned within parity to two treatments while still in the farrowing crates. After weaning, sows were housed in the breeding room in individual stalls according to the sequence in which they entered the room.