From a 2004 interview:

Concerning bestiality - should people have sex with animals, seen as willing participants? -- he responded, "I would ask, 'What's holding you back from a more fulfilling relationship?' (but) it's not wrong inherently in a moral sense."

Is there anything wrong with a society in which children are bred for spare parts on a massive scale? "No."

From a 2001 review:

But sex with animals does not always involve cruelty. Who has not been at a social occasion disturbed by the household dog gripping the legs of a visitor and vigorously rubbing its penis against them? The host usually discourages such activities, but not everyone objects to being used by his or her dog in this way, and occasionally mutually satisfying activities may develop.

Article on a 2015 case of a woman sexually assaulting her student, a mute man with cerebral palsy:

If we assume that he is profoundly cognitively impaired, we should concede that he cannot understand the normal significance of sexual relations between persons or the meaning and significance of sexual violation. These are, after all, difficult to articulate even for persons of normal cognitive capacity. In that case, he is incapable of giving or withholding informed consent to sexual relations; indeed, he may lack the concept of consent altogether.

This does not exclude the possibility that he was wronged by Stubblefield [the assaulter], but it makes it less clear what the nature of the wrong might be. It seems reasonable to assume that the experience was pleasurable to him; for even if he is cognitively impaired, he was capable of struggling to resist, and [...] it is implausible to suppose that Stubblefield forcibly subdued him. On the assumption that he is profoundly cognitively impaired, therefore, it seems that if Stubblefield wronged or harmed him, it must have been in a way that he is incapable of understanding and that affected his experience only pleasurably.

There's also this statement by the National Council on Disability in response to Singer's appearance on a radio show.

Singer's statements supporting eugenics, which is what he's most notorious for, are also not difficult to find.