If fed or implanted for hair growth, melatonin gives you a very specific window in which you can expect a peak in hair growth, a holding period, and then a shuck. It's usually 90-110 to reach peak, and 120-140 days until you see the shucking start. Sometimes they won't shuck hard, but if you're relying on melatonin to get hair, they probably will. If you start feeding it after your calf is growing new hair, it can also make them shuck it and start a new hair cycle. It's a very useful product in specific applications, but I would be hesitant to use it on an animal that I want to target for multiple shows, such as a jr national and style fair, or state fair and a fall or winter major.
Melatonin is a naturally occurring hormone that obviously has a lot to do with hair growth. When you feed or implant it, the animal utilizes the extra the only way it knows how : more hair. The kelp is a little more subtle. Instead of an overload of one thing, it delivers a wide array of nutrients, some of which slow the heart rate and otherwise help with heat stress. It's not that the kelp magically makes hair grow, it just helps the calf get theist out of its environment. Tasco is derived from kelp. Feedlots have fed it for decades to assist with heat stress.
