Slooooooow eater

My horse is paddocked with two ponies. They wear the pants so to speak. Amir's a rather slow eater and the ponies just inhale their feed and then bully him away from the rest of his. My horse is fed substantially more than the ponies considering one is an extremely easy keeper and the other is at a very good weight. There's no way to separate them for feeding and since he's been with them full time for the last 2 months, he's dropped a bit of weight. Not a lot, he's by no means under weight, but he's just not where I would like him to be. His work load is also increasing so I would like for him to stay at a good weight.
I've been thinking about trying him on Appetite. He hasn't got a loss of appetite and he's not a picky eater, I was just wondering if it was worth trying him on this stuff while he's with these ponies to try and encourage him to eat a little faster or at least want to try and man up and fend for his food.

APPETITE 946ML

I wouldn't waste my money on that, looks like a product designed to just make the food taste better. I don't know of a way to speed horses up when they're eating, but it's not a good idea because it can cause choke sometimes. I have to stand with my horse while he eats because if not my others will get into his feed. You could also try getting a bag designed to attach to a halter and go over the horse's head, or you can tie a haystring to a small bucket to slip over his head.

Tie the ponies at feeding time