For my easy keepers, I let them out on grass for about 3 hours just before I feed their ration balancer because they always come back to the barn for that. Otherwise, good luck catching my guys when they’ve been let out on grass.
My insulin resistant mare is out with a grazing muzzle so she has to be on short grass since muzzles don’t work with long grass. For the last three summers, she has not foundered with a few hours per day in short grass so I’m thinking the sugar content on short grass can’t be that much of a concern over short periods. I’ve also read all the literature on soaking hay but my observations were that my mini’s health was no different during the two years I soaked her hay. I eventually stopped doing it because it’s a huge pain and was making no apparent difference in her health.
I used to keep half my pastures short and half long. The horses picked up a lot of ticks (and Lymes disease) when the grass was long so now my horses never come into contact with long grass. Tick-borne diseases are a serious concern where I live.
I recommend reducing turnout time to about 3 hours per day. I once read that a study showed that a horse let out on pasture for 4 hours per day will eat as much grass as if they were out all day because they eat faster when they know they have less time. The study apparently found that turnout time of less than 4 hours is required to reduce grass intake. If possible, spreading hay in a thin layer throughout your dry lot will make the horses have to move more, and possibly eat less.
