We used it last year and it work good. Very expensive though. We used it with just rinsing, blowing out and fans and they grew great hair without shedding. We did not use melatonin with it. I was told to be careful using it on young calves.
I have used this product and it worked great. I fed the bare minimum and the calves were growing a ton of hair. The other product that I found that works great to grow hair is Hide N Hair. I feel it works better than Epic and it is a powder where my calves sometimes would not eat the Epic pellet.
Epic is about $65.00 for 25lbs which does one animal for 45 days, not sure about hide and hair. Our feed dealer (Keller) is a sunglo dealer so it is easy to get. Will be using it again this year.
I have also used Shag to see if it worked and I did not have any success with it. The hair supplements that I had the most success was Hide N Hair and Epic.