We have used Fast Fat on heifers for 30 days and saw no adverse affects. Not sure about any others, but I'd have no problem using it again. Of course, we use it to try to get some condition on a green one - not to get extra fat on one that's already in good condition.
I just mean any supplement. Of coarse not the ones that state NOT to feed to breeding animals. Just a supplement that would add weight to a green heifer faster...not to fatten/finish. We typically have some problems getting calves to look good for the fall run of shows in Canada after weaning. Some do ok, some have no appetite and dont look good for the shows. Just curious whether it is worth it in the long run to feed a supplement.