Propylene glycol offers a good way to counteract ketosis. But, there have been some questions about how to best deliver it to cows since drenching can be a difficult experience for cows and people. Research at Penn State University, published in the SeptemberJournal of Dairy Science, shows that serum (blood) insulin peaked more rapidly and at a greater concentration for cows receiving propylene glycol via drenching, but not when it was provided as a part of the TMR.
Therefore, feeding dry propylene glycol (as a top-dress or included in the ration) was not as effective as drenching, say study authors. The effects of drenching dry propylene glycol into the rumen were comparable to orally drenching liquid propylene glycol.