We fattened our Holsteins for a lot of years on a self feeder.  Sunflowerhulls or ground cobs for roughage.  Threw them some cornstalks everyday in the cold weather to avoid brain fever.  Worked great.  If you're looking for a reasonable guy on a variety of tmr units check out www.postequip.com   Has a used inventory with prices on his website.  Deals all over the US.