The website "The Least Suffering for the Smallest Number: Working papers in Philosophy as Therapy by Socrethics" has a nice collection of utilitarian articles. One that I particularly like discusses wild animals: "Utility and Pain in Biology." A recent piece is "Negative Utilitarian Priorities."

The author is glad to hear feedback about any of the essays. I've pointed him to this forum page, so you can leave comments in this thread.