Wolly Monkeys are hard to keep alive in Zoos, due this there are low numbers present in captivity in this days. They are susceptible to several nutritional health problems, etc.
Maybe this one was taking adult to this enclosure, its hard to believe that a Wolly Monkey would survive for a long time in such conditions.
Judging from the shadows of the mesh, I'd say the flash was on for this photo, which might partly explain the slightly washed-out colours on the monkey.
