ST. PAUL, Minn. — One of the greatest challenges facing swine breeding herd managers today is increasing sow longevity in the herd, especially when gestating sows are group housed. Today’s females have been bred to produce and support large litters, and this increases the pressure and nutrient drain from their bodies. University of Minnesota veterinarian John Deen said the lactating sow undertakes more stress on her body as a function of weight than any other animal. Increase in lame