Singer describes famine as a preventable form of suffering that is inflicted upon millions of people each day. He passionately states that, "If it is in our power to prevent something bad from happening, without thereby sacrificing anything of comparable moral importance, we ought, morally, to do it". He suggests that we forgo all the unnecessary excesses of life, and donate time and money until the suffering ends or we are reduced to a level of marginal utility in our effort to help those in need. The extremes of this view may seem absurd, but the examples of that philosophy in Mother Teresa and Grampa Dobri do shine as ethical beacons throughout the world.
Thus there is little doubt that reducing the suffering of man is ethical, but can this philosophy be applied equally to non-human animals? It's difficult to know Singer's opinion on this. While he does state that non-human animals can suffer and that they have moral rights, he also says that "nowhere do I state that the capacity of animals to enjoy life is equal to that of humans." This suggests that he would not advocate reducing yourself to a level of marginal utility in order to prevent non-human animal abuse. He may even advocate reducing the suffering of those with the higher capacity to suffer first (humans before non-humans?).
If that's the case then there rises a rather interesting problem within Singer's Animal Liberation. Though non-human animals have a moral right, it is a reduced moral right when compared with humans. Therefore, though aid to non-human animals could be considered ethical, It is immoral to act on them until all human suffering has been resolved.
PETA, and other organizations built off of the Animal Liberation philosophy, may have solved that road block by considering humans and non-human animals wholly equivalent. Though that leads to another slew of ethical considerations. Like protesting Obama swatting a fly, or protesting experiments on cockroaches.
http://abcnews.go.com/blogs/politics/2009/06/peta-says-no-more-flykilling-sends-obama-a-humane-fly-catcher/
http://wkzo.com/news/articles/2013/nov/01/peta-opposes-remote-control-cockroaches-designed-by-michigan-company/
