Tamed Otters do not eat regular meat, only fish meat. My otter was refusing to eat even though she had plenty of meat in her inventory and plenty of meat in a nearby trough. To remedy this, I tried multiple things; moving the trough closer, giving her more meat, and even force feeding her. She would not gain hunger with regular meat. The moment I got fish meat, she ate. I'm not sure if they can eat other types of meats like mutton though.
Helpful Tip: Did you know you can hatch eggs using these mfs? First, tame 3 otters, place them in a triangular shape with the egg in the center, then BOOM!! u got yourself a baby dino. Nature's incubator. Up these and let everybody know.