the way I look at it is two fold
1: I'm limited for space and as such I know that I can't keep every slightly deformed animal I will ever produce. I also know that selling these animals is not only unfair to the animal but to the person I'm selling it to. So with limited space and no way to move the product/animal I know I will be forced to cull some of the deformed animals simply in the interest of business.
2: If the animal has the desire and drive to live. It eats and makes a whole hearten attempt at making a go of it I am of the opinion that I produce the animal intentionally and because of this I owe it the chance to survive in spite of its deformity.