Steve:
I bred with a yearling last year and he was matched with seven doe. It wasnt enougn for him. All day long he would pace my fences trying to get at the doe in my other pens. He continued this behavior long after the rutting season. Ultimately and unfortunately he didn't drop his antlers until late May. He was unable to catch up with his antler growth. Vet was of the opinion that we didnt provide him with enough doe, but then again she doesnt know much about whitetails. I guess it just depends on the deer your breeding with, in fact, the deer I'm talking about never even appeared to lose any weight.
I would venture to say that drawing semen from a yearling would have no adverse effects.
Daniel
www.hollowroadwhitetails.com