Historically, animals are chattel —property, like a toaster or a lawnmower. Animal welfare laws are exceptions to this rule; they say you cannot destroy your property in certain ways (cruelly). But you still own it.
Conversely, welfare improvements often pave the ideological road for rights. Once a society accepts that a pig has a freedom to express normal behavior (rooting in dirt), it becomes harder to justify confining that pig in a gestation crate. Each welfare concession acknowledges a right implicitly. History shows that rights rhetoric pushes the welfare
History shows that rights rhetoric pushes the welfare floor upward. When the Animal Liberation Front releases mink from a fur farm, they break the law—but public outrage often leads to stricter welfare regulations for the remaining farms. When a philosopher argues that eating animals is murder, the overton window shifts, making "cage-free eggs" seem reasonable. the overton window shifts
The rights position is absolutist. If an animal has a right to life, then killing it for food is wrong, regardless of how "humanely" it was raised. If an animal has a right to bodily autonomy, then using it for biomedical testing is a violation—even if the research might cure human disease. making "cage-free eggs" seem reasonable.