By Mike Leggett AMERICAN-STATESMAN STAFF Sunday, November 07, 2004 Once upon a time, when a deer hunter dreamed of a big buck, he imagined a giant whitetail posed against a rising sun on a frosty hillside, blowing twin jets of steam from flared nostrils while surveying his brushy kingdom. Now there are other "big bucks" in the woods: A Texas partnership recently spent an astounding $450,000 to buy a live, 4-year-old whitetail. Though its stunning horns were a definite selling point, the most valuable thing about this magnificent animal wasn't his trophy potential but his semen. At $3,500 per dose,...