Domestic animals, such as cows and pigs, and laboratory rats would not exist were it not for our bringing them into existence in the first place for our purposes. So is it not the case that we are free to treat them as our resources?

No. The fact that we are in some sense responsible for the existence of a being does not give us the right to treat that being as our resource. Were that so, then we could treat our children as resources. After all, they would not exist were it not for our actions–from decisions to conceive to decisions not to abort. And although we are granted a certain amount of discretion as to how we treat our children, there are limits: we cannot treat them as we do animals. We cannot enslave them, sell them into prostitution, or sell their organs. We cannot kill them. Indeed, it is a cultural norm that bringing a child into existence creates moral obligations on the part of the parents to care for the child and not exploit her.

It should be noted that one of the purported justifications for human slavery in the United States was that many of those who were enslaved would not have existed in the first place had it not been for the institution of slavery. The original slaves who were brought to the United States were forced to procreate and their children were considered property. Although such an argument appears ludicrous to us now, it demonstrates that we cannot assume the legitimacy of the institution of property–of humans or animals–and then ask whether it is acceptable to treat property as property. The answer will be predetermined. Rather, we must first ask whether the institution of animal (or human) property can be morally justified.