One possible version:
Yesterday we had a discussion about if we should keep animals in zoos. Twenty of us thought that animals should be kept in zoos. Then we can see different kinds of animals there and all the animals will be taken good care of. Thirty students had a different opinion. They thought that animals shouldn’t’t be kept in zoos，because animals come from the nature and they love to live in the natural environment . If they are kept in the cages, they can’t move here and there. Keeping animals in cages is really bad for them.