Shuhan's objection: her idea is giving the example of a lion hunting other animals for food which is a basis for living in the area. This is similar to we human being that we need to eat other kinds of animal, which is not morally wrong. We just try to eat and live in the world but we make other animals suffer. Thus we cannot say all the animals need to take same moral consideration.
Singer response: there might be two kinds of ideas. First, humans have a better understanding of moral ideas and pains. They understand what kind of activity is morally good or wrong. what is more, they can use the least resources to achieve what they want. For example, animal factories use scientific ways to produce meet to cause fewer pains. people will also feel happy when they take food, so that is not morally wrong.