My minis are in the pasture all day and put up at night. The spring grass is growing like wildfire right now. Is it OK to leave them out? I don't feed them any grain or hay in the morning and only a half a cup of grain at night to get them to come in. Is this an appropriate feeding program? And are they gonna get too fat with all that grass. They are not show horses. One is too fat now from the winter and one is not.