Please keep in mind that I live in Australia and we have VERY hot weather at the moment, so he definitely won’t miss his thick winter coat if I clip it anyway.
TODD
It will grow back the same. It appears to be coming in thicker because it is standing up and kind of spikey at first. Once it gets a bit of weight and length to it, it will lay down again. You just will have to put ups with it looking kind of odd for a bit. When the mane reached about 3″ and was not laying down we would sometimes braid it using bands.
I have roached or hogged several horses manes and never had anyone grow back thicker. Some of them I wish they would but no luck.
Minnis are notoriously thick maned and have a heavy hair coat.
I own 3 horses, and from my personal experience body clipping will NOT make their coats grow back thicker. I roach their manes when another horse takes a bite out of them. I only do that so the manes will grow back even. They should return to the same thickness. I had a draft horse(Clydesdale) colt and I buzzed off all of his winter coat because he wasn’t respecting the electric fence either. I’d say go ahead and cut!! If the temperature drops with a wind chill below 40 degrees, you may need a blanket.