Assuming that animals feel physical and emotional pain in some way that is comparable to human feeling, why does Judaism discount their needs? I am interested to hear rabbinic discussions about this.
I suppose the first thing to consider is whether chazal hold that animals do have such feelings at all.
Some issues include:
There are cases where Jewish law requires animals to be made to suffer, including times when a human made a choice that causes the animal to be punished (see here), and the fact that alleviating animals' suffering on Shabbat would not always be allowed.
There is a concept of not causing 'unnecessary' suffering to animals; that is, suddenly the suffering is acceptable to us if it is useful for our (human) purposes. This includes using animals for research.
Pests can be killed even using quite painful traps and pesticides.
It says here that a calf found in the womb, as long as it was removed after the mother died, and that mother was properly slaughtered, can be eaten without slaughter and that, potentially, even eating its limbs while it is alive is permitted (because, technically, it is considered part of its mother's body, not a living creature in its own right).
I'm not asking about the difference between killing an animal and killing a human, or using an animal for labour or pets in a caring way (perhaps akin to the license the Torah gives to own slaves - but requires us to treat them with compassion).
But purely in terms of causing or allowing pain, fear, and grief to animals I am trying to understand the discrepancy between my perception of reality (that the animal is a living thing that feels pain) and the technical approach allowed by the Torah.