You could try soured milk (similar to soured colostrum). Take mastitic surplus milk (no antibiotic residue) in a day and allow it to "grow" or ferment using buttermilk or other soured milk to start the fermentation. The milk will drop to a pH below 4.5 and remain pickled for several days to a week (depending on day temperatures). Once a batch has fermented, DO NOT add fresh waste milk to it; it will start fermenting a second time, and it will deteriorate (go bad). Fermented or pickled milk could be mixed with fermented milk after both batches are stable to save space or consolidate batches. If drug residue remains in the milk, it will not ferment (drug residue kills the lactic acid fermenting bacteria).
Mike Hutjens, Extension Dairy Specialist, University of Illinois - Illini DairyNET
