WESTFIELD, Wis. (AP) — Izzle, Timon, Batman, River and Mars spent years confined inside a lab, their lives devoted to being tested for the benefit of human health.

But these rhesus macaques have paid their dues and are now living in retirement — in larger enclosures that let them venture outside, eat lettuce and carrots, dip their fingers in colorful plastic pools, paint, and hang from pipes and tires — in relative quiet.

More research labs are retiring primates to sanctuaries like Primates Inc., a 17-acre (7-hectare) rural compound in central Wisconsin, where they can live their remaining yea...