A commercially, premixed complete dairy feed or protein supplement has several advantages compared to an on-farm blend. These advantages include less inventory of five to 10 ingredients on the farm, less shrink, no money invested in feeds that may take months to use (need to purchase bulk amounts such as semi loads or tons for economical purchases), fresher ingredients as you may not turn over bulk amounts quickly (important for vitamin stability), and fewer mixing/blending errors.
Concerning cheaper ingredients and quality risks, this depends on the integrity of the mill and company/co-op (not a major concern).
Mike Hutjens, Extension Dairy Specialist, University of Illinois - Illini DairyNET
