Well Mark, I have never noticed that winter born pups might make bigger dogs than summer born ones....that's some food for thought. I'm thinking that you might be onto something there, since you've made that certain cross at both times and have seen the pups right on up.
pups, dogs tend to eat more in the colder weather. Is it possible that the pups get more growth nutrients from the dog food because they eat more in the winter even though they burn more energy in the colder weather???
did the winter pups get a higher quality food than the summer pups???