well,first off you dont need to keep them on milk for 3 months..they are usually weaned (on dairy farms) by 5 weeks,as long as they are eating grain and hay good you can wean them off milk,around 4-5 weeks start making the milk weaker and weaker and they will wean fine,I never put milk babies on grass,makes them get all pot bellied and ugly,dry hay is better until they are weaned,I grew up on a dairy and ran one for many years,3 months on milk is just wasting money,Holstiens make very excellent lean meat,as do jersey,but they take longer to get to kill weight because they have a lot more bone growth to do before they start putting on muscle,the really lean meat you buy in the store is usually Holstien,and as far as dehorning,you can always have a vet do it,wait until they sprout about 2-3 inches and the vet can do it with a dehorning tool,if you have a weak heart you wont like this part,as they have little holes in their heads for a while,and they bleed,but as long as the vet pulls out the vien after removing the horn they will be fine,its better to do this when its cooler out for flys,and they will have a headache for a day or so.we did it ourselves a on the farm but you wont want to.and they dont need to be on a bottle for more then the cholostum,you can pail train them within a few days of birth,but it takes patience as they are not the most intelligent creatures..but at least then you can dump it in a pail and be on you way.
