Ok, and that will continue to rise quickly if they are only 5 weeks. How much is this feed in your area?
So now you can shop around for prices and see what the best deals are. You can tell them you'll be buying 300 pounds of feed now, and will be needing even more every month after that. They may even set you up an account where the more you buy, the better rate you get on the feed. I love wheeling and dealing on stuff like this, its fun to get people competing for your business.
Oh and don't let people not take you seriously because of your age. This is just business, age really has nothing to do with it!
