So, I have dogs and cook their food and have for over a decade now. An article here, explains three major reasons for doing this. I personally find my canines stay healthier, I know exactly what is going into their stomachs and can adjust supplements and the like accordingly!
I juice...5-7 days a week. So many folks say that you lose so much with the grindings, but I waste NOTHING. I use the grindings in my dog food and I also have horses and mix that which I don't need for the dog food into a bit of grain, wet it and the horses have an amazing treat as well!
Give it some thought and your dogs (and horses) will appreciate you! And yes, I freeze the grindings for later use!