Should he have a grazing muzzle of for part of the dayAs long as the grass is green and growing, he doesn't need hay unless he isn't used to grass. If he has been penned prior to you getting him, then it would be a good idea to slowly introduce him to grass by filling him up on hay prior to turn out and limiting his time on grass - start out with an hour on grass - and slowly increase over the time period of a couple of weeks until he is used to it. Be careful about the weeds - they have a high protein content and can easily cause founder.
Not in an uncontrolled environment where you can't watch him at all times. He can snag a muzzle and hang himself, he could go to get a drink and drown himself (depending on the muzzle) etc. I am absolutely not a proponent of grazing muzzles unless used in a very cautious, safe, way with full owner participation!Should he have a grazing muzzle of for part of the day
I use grazing muzzles too and I can't think how a horse could drown in one that was properly used with a breakaway and/or a breakaway halter.If you notice him getting fat pads, a cresty neck, or just getting too fat etc. a grazing muzzle is definitely an option.
I've used breakaway deluxe Best Friend muzzles on two mares for the last 5 or 6 years with no problem. I did have one mare catch hers on a fence post, it broke very easily as it was meant to, and I replaced the snap with the extra provided with the halter. I see no way that a horse could drown itself in a Best Friend grazing muzzle, or really any grazing muzzle.