I have always heard not to feed "grow N shine" to heifers. Don't know if its true, but have been told by quite a few not to.
If I recall Kirk said Shag worked on heifers.
Somewhere, I think it was on this forum, I read that heifers shouldn't be fed Shag if you were going to try to breed them. If I run across that thread again, I will let you know which one it was.
My family and I have used Grow and Shine for the past three years all three years our calves have had 4 or more inches of hair. We squirt it in there mouths every morning and we wash our calves 3 times daily and they each have 2 fans on them for 15 hours a day i would recommended Grow and Shine to anyone over shag and the plus to Grow and Shine is it has a calmer in it that works really well.
Grow and shine is just melatonin, Shag has melatonin plus other stuff. Both are just fine for heifers - for certain. You can find journal articles where melatonin is used to improve reproduction in other animals.
Be VERY careful with Shag on heifers...heard lots of stories from reputable people about it. We also fed it to a heifer, and with our luck she never bred( to many factors that could play into that though)..I would wait till shes safely bred!
I have been told many times not to feed Grow and Shine to heifers. Might be one of those things where "in theory" and "reality" are not agreeing.
My personal opinion: Too many people are saying many of these supplements are not good for heifers. I would prefer my heifers to breed and become a cow, instead of having 4 inches of hair and have a purple ribbon in the bottom of some drawer somewhere (or bottom of the show box for the next year).
not sure on either of the two, but I know Epic is safe for heifers. Have feed it to 6 heifers and all were either bred during the time on epic or shortley after.