Hi, I'm Dr. Jill. First off, well done helping him get back from a bad laminitis episode...not an easy thing!
Unfortunately, pasture time can be a very complex issue. You may have heard the term "non-structural carbohydrates" before...these are part of what we think about causing problems with lush grass laminitis in horses.
These levels can vary by the type of grass in the pasture, time of day, weather, etc. They tend to be lowest in the morning as well as after periods of cloudy weather (product of photosynthesis). They're highest in the afternoon, after periods of drought, and after periods of cooler sunny weather.
So I'd recommend turning him out first thing in the morning or late evening/overnight to help decrease risk.
They can also be very crafty with grazing muzzles, and I think the key, as with most things, is not making drastic changes. So I'd start by turning him out for maybe 30-60 minutes, seeing how he tolerates the muzzle and how much grass he can get, and increasing from there.
Some horses are able to graze just as well with and without muzzles, so owners tape the holes and use them as just a regular muzzle so they can have turnout time and have a controlled diet.
He may be able to go out all day with the grazing muzzle, but I'd error on the side of caution (especially since they're at increased risk once they've had a laminitic episode) and start slow.
Hope this helps! Please let me know if you have any additional questions or concerns and I will gladly address them. Thanks and best of luck!
I have a Pear tree.Apple tree and a oercimon tree in my pasture. Is this a problem?
If I understood you correctly he can be turned out at 9 or 10 in the evening for overnight and in the morning until about noon..