In contrast to animal rights, the concept of animal welfare is valid.
At the most general level, morality as it pertains to animals under our control is directed by holding life, in general, as a value. Wanton destruction or damage to life is immoral as it implies the sacrifice of a value. There is a clear difference between someone who kills animals simply for the (perverse) enjoyment of killing and the hunter who kills to obtain a product he values.
At a more specific level, animals provide distinct values to us. The pets we own bring us a great deal of happiness and their welfare is a clear value to us. Production animals are necessary to provide the animal products we use and enjoy, and they generally produce better the more their health is protected and enhanced. It is in the farmer's or rancher's best interest to see to the welfare of his herds. Even though the death of the animal may ultimately be required, it is right to protect its welfare during the time it is alive. Any conscious attempt to degrade the quality of these animals' lives is immoral.