I'd say his problem is a combination of poor nutrition, inadequate exercise and improper hoof care. No blame being placed as I gather in some countries care is what it is. OP you are making good effort. With the right info perhaps we can tailor it to suit his needs better.
What would help would be pictures of the bag of feed - showing name, brand and ingredients, if listed the guaranteed analysis (which may not be available). Same for the minerals. Do you know what type of grass is in the pasture and the general region you are in so we can get an idea of soils and possible mineral loads in the water?
Last edited by loosie; 06-20-2019 at 08:56 PM.