If the food supply is good, and the winter severity index is low they keep their horns clear out into early April. Hanging around those grain bins I would say they are eating pretty good.
At my neighbors farm there is beet pulp, corn silage, and stuff from a potato processing plant, and gluten from an alcohol plant. That stuffed is mixed to a ration and fed to the cows. The deer come to the feed bunks just before dark and clean up what the cows left.
The deer really like the the beet pulp, and potato waste. There is about 40-50 head every evening in the yard feeding. Many of the bucks, big and small are still carrying horns yet.The does and fawns are all fat and sassy. The deer come there in December and yard up. They migrate to the farm every winter, and at spring break up they leave and go back to were they came from further out on the prairie.