I can not stand to watch these little ones suffer. It is a vitamin and electrolyte supplement, and it is very good. I use it with every batch of chicks I get. He may have a reason for suggesting you withdraw the terramycin, perhaps because the chicks are displaying symptoms that terramycin works on. Perhaps the cobs are a little too rough, or there is a dust or residue problem with them for some reason.
Hatcheries are like seed companies.
They cannot supply bad chicks or seeds to people because word tends to travel very quickly. If your seeds don't sprout, the odds are very good there is an environmental reason for it. Just for the record, when I have had chick losses, it was almost always when I ordered 25 that come in the small boxes. Rarely have I had problems when ordering 50 or 100 or more. With just 25, there is not much heat generated to keep them warm, and you must know that at Murray McMurray, for example, the chicks are driven from the hatchery to St. Paul, where they are put on postal service planes, flown to hub post offices, then trucked to your local post office.