The practical reality is that existing cost-benefit analyses of animal welfare policies are speciest: they only explicitly consider the benefits and costs of the policy to people.
Jayson Lusk & Bailey Norwood, ‘Animal Welfare Economics’, Applied Economic Perspectives and Policy, vol. 33, no. 4 (2011), p. 468
[T]o the extent that we view morality as not simply a human creation, a device whose sole purpose is to ensure cooperation among humans, and thereby promote human flourishing, we have powerful reasons to reject the view that the interests of animals are less significant than the like interests of humans. Such a rejection will render much animal experimentation morally unacceptable. This is not a conclusion that will be eagerly embraced by the scientific community. It is, however, the conclusion best supported by a careful examination of the relevant moral reasons.
Alastair Norcross, ‘Animal Experimentation’, in Bonnie Steinbock (ed.), The Oxford Handbook of Bioethics, Oxford, 2007, p. 666
Under the Gentoo and Mahometan religions, the interests of the rest of the animal creation seem to have met with some attention. Why have they not, universally, with as much as those of human creatures, allowance made for the difference in point of sensibility? Because the laws that are have been the work of mutual fear; a sentiment which the less rational animals have not had the same means as man has of turning to account. Why ought they not? No reason can be given. If the being eaten were all, there is very good reason why we should be suffered to eat such of them as we like to eat: we are the better for it, and they are never the worse. They have none of those long-protracted anticipations of future misery which we have. The death they suffer in our ands commonly is, and always may be, a speedier, and by that means a less painful one, than that which would await them in the inevitable course of nature. If the being killed were all, there is very good reason why we should be suffered to kill such as molest us; we should be the worse for their living, and they are never the worse for being dead. But is there any reason why we should be suffered to torment them? Not any that I can see. Are there any why we should not be suffered to torment them? Yes, several. See B. I. tit (Cruelty to animals.) The day has been, I grieve to say in many places it is not yet past, in which the greater part of the species, under the denomination of slaves, have been treated by the law exactly upon the same footing, as, in England for example, the inferior races of animals are still. The day may come, when the rest of the animal creation may acquire those rights which never could have been withholen from them but by the hand of tyranny. The French have already discovered that the blackness of the skin is no reason why a human being should be abandoned without redress to the caprice of a tormentor. It may come one day to be recognized, that the number of the legs, the villosity of the skin, or the termination of the os sacrum, are reasons equally insufficient for abandoning a sensitive being to the same fate. What else is it that should trace the insuperable line? Is it the faculty of reason, or, perhaps, the faculty of discourse? But a full-grown horse or dog, is beyond comparison a more rational, as well as a more conversible animal, than an infant of a day, or a week, or even a month, old. But suppose the case were otherwise, what would it avail? The question is not, Can they reason? Nor, Can they talk? But, Can they suffer?
Jeremy Bentham, An Introduction to the Principles of Morals and Legislation, London, 1789, chap. 17, sect. 4, n. 1
The reasons for legal intervention in favour of children, apply not less strongly to the case of those unfortunate slaves and victims of the most brutal part of mankind, the lower animals.
John Stuart Mill, Principles of Political Economy, in The Collected Works of John Stuart Mill, Toronto, 1988, vol. 3, p. 952
[W]e cannot concentrate only on benefactors to humans. Perhaps Peter Singer, the most influential person in promoting the welfare and rights of animals, will ultimately have contributed more to the development of the universe than benefactors merely of humans. Perhaps Singer’s book Animal Liberation will (over the centuries) have increased the happiness, health, and lives of animals to such an extent that it adds up to a greater amount of goodness than the human development that will be the total consequence of (say) Gandhi’s actions.
Quentin Smith, Ethical and Religious Thought in Analytic Philosophy of Language, New Haven, 1997, p. 217
I regard Peter as one of the great moralists, because I suspect that more than anyone he has helped to change the attitudes of very many people to the sufferings of animals. Peter is a utilitarian in normative ethics, and a humane attitude to animals is a natural corollary of utilitarianism. Utilitarian concern for animals goes back to Bentham, who, presumably alluding to the Kantians, said that the question was not whether animals can reason, but whether they can suffer.
J. J. C. Smart, ‘Reply to Singer’, in Philip Pettit, Richard Sylvan and Jean Norman (eds.), Metaphysics and Morality: Essays in Honour of J. J. C. Smart, Oxford, 1987, p. 192