U.S. hog producers broke through the 10-pigs-per litter barrier in the March-May 2011 quarter, according to the latest count. Averaging 10.03 pigs per litter, the U.S. hog production industry is now positioned to possibly eliminate Canadian hog producers’ longstanding litter-rate lead. U.S. litter rates have trended upward for more than two decades due to widespread adoption of technologies that have improved animal handling procedures, breeding methods, and nutritional composition. Technological innovations contributing to larger litters, superior survival rates, and improved weaned-pig numbers are both a cause and a consequence of the hog industry’s move from a very large number of small operations to a relatively small number of very large, specialized operations.
source: usda