In its 2008 Annual Report, the Humane Society of the United States (HSUS) states as one of its goals for 2009, "Reduce the suffering of farm animals by banning tail docking and other utilations, imposing more state bans on factory-style confinement systems, and convincing major food retailers like Wal-Mart and Costco to stop selling eggs from battery cages and other factory farm products."
While some types of sheep do not require tail docking, reasonable people know that tail docking improves the health and welfare of lambs, while having no detrimental effect on health and productivity. The research is clear on this matter.
