It is assumed that they are trying to mass produce the peptid in a laboratory, not making the babies suffer. Wouldn't be animal tears anymore.

(I wonder of the mice could enter in a depressed state at a middle term by that. Not directly related, but most humans (visual animals) would get depressed, or emotionally touched at least, if forced to work in a room full of posters of crying children. Maybe mice would have developped a similar response with olfactive signals..)