A study by researchers at iowa state university found that placing pregnant sows in group housing structures ( hoop barns ) could be more cost - effective and just as productive as placing them in sow stalls 爱荷华州大学研究发现，把妊娠母猪大群饲养（铁环圈起来的猪舍里）可以更有效利用猪舍，生产性能与把每只母猪单独放在猪栏里没有区别。
