This sentence is specially written for the king to teach him to cultivate the heart of caring for people from caring for animals.
A gentleman refers to a man of practice and cultivates his virtue. Practitioners should first cultivate compassion, so try not to kill animals, but to cultivate love for all animals. A gentleman is an animal. He can't bear to see his life and die before he loves the people around him. The kitchen is a place to kill people, as well as slaughterhouses and battlefields? Practitioners should try to stay away from these places. But it doesn't mean that people in the kitchen, slaughterhouse and battlefield are not good people. Don't misunderstand the teachings of Confucius and Mencius.