A mixture of barrows and gilts as fed for four trials over two years in bedded hoop structures and a confinement building with slotted floors. When the central Iowa summer and winter feeding periods for two years were combined, the trials showed that as expected the barrows grew faster, had thicker backfat, smaller loin muscle areas, and lower percentage of lean than the gilts. The hoop-reared barrows and gilts grew 3% faster, but had thicker backfat (7.9% more for barrows and 6.5% for gilts) and 5% smaller loin muscle areas than their counterparts in confinement. The hoop barrows and gilts were 1.3 percentage units less lean than the confinement barrows and gilts.

During the summer, the pigs in hoops grew faster than the pigs in confinement. During the winter the growth rate was similar. These trends were consistent for both barrows and gilts. However, during the summer, the barrows had 10.6% thicker backfat and the gilts had 11.1% thicker backfat than their counterparts in confinement. In winter, the hoop barrows had 5.2% thicker backfat than the confinement barrows, but the gilts’ backfat was similar. Also, during the summer, hoop barrows and gilts had 4.5–4.7% smaller loin muscle areas than their counterparts in confinement. During the winter, the hoop barrows and gilts had 5.7% smaller loin muscle areas than their counterparts in confinement. Therefore, during the summer, barrows and gilts had 1.6–1.7 percentage units less calculated lean than pigs in confinement. And during the winter, hoop gilts and barrows had 1.0–1.2 percentage units less lean than pigs in confinement.