Depends on several things. How old is the cow? Where did she come from (commercial dairy that culled her or home raised?) How much milk do you want from her?
Okay, first calf heifer...nice udder...good flesh when she calved....you want 2 gal milk a day for the house plus all the calf wants. 5-10 lbs grain once a day max....watch her condition but also watch the calf. The cow is going to make too much milk for the calf and it will probably scour some in the beginning. Holsteins just make too much milk, that's how they have been bred for years. I would let the calf in with the cow after I have milked her and let it stay 12 hours. Then separate the calf, milk the cow in 12 hours put the calf back with her. So, milk in the morning, put calf in with cow, separate calf in eve, milk in morning...repeat. And honestly, I would have 2 calves on that cow not one, so that the udder does reach full potential without too much milk to scour a single calf. It has been proven that increased milk removal in early lactation will increase the overall production.. and overall better udder health by complete removal frequently of the milk. It is sooooo easy for a hol x to get mastitis simply because the udder doesn't get completely milked out. So if the calf doesn't get it milked out then she can harbor a bacteria that may not get completely removed through human milking, and next thing you know she has mastitis.
Older cow.....culled from a dairy....probably 10 lbs grain once a day, same as above but watch for condition and milk fever. Not only can they get milk fever early on, but they can get late lactation milk fever which is more potassium imbalance than the calcium like early on.
Older cow....not from a dairy, or just a low producer....condition and amount of milk wanted from cow.
I feed a 16% feed, not 22%, and up the amounts a little bit. But I have 2-4 calves on a cow at any one time. I want them to keep up their condition and I just like the 16% "sweet feed" from our local mill, and the cows eat it good. I have one that doesn't like sweet feed and she gets the 17% all purpose pellet that we get, to feed to any/everyone that gets feed for any reason. I don't push the cows like a commercial dairy, but they do make more milk than an average family cow. All my cows have been milked at different times, sometimes for a couple of weeks at a time 2x a day, and I want at least 5 gal milk a day from each, minimum. I find that is a breaking point for me to justify the feed inputs against the calves raised/sold. They each get approx half a 5 gal bucket of feed a feeding. The big hol/jer older cow gets about 2/3 a 5 gal bucket but she is a pretty big cow. I do add some of the 38% pellets to hers, usually about a 1 lb coffee can full, as she just gets thin. And believe me, she likes to eat. One other thing I do, each cow gets a leaf(section) of alfalfa HAY when they come in the barn with their grain and they all pretty much clean it up. I keep them in for 1/2 hour to an hour to eat then let them back out loose in the pasture. If I am sitting down to milk, the hay keeps them fairly quiet and content while I am finishing up with whomever I am milking that day. When the calves get a couple of weeks age on them I don't worry so much about the scours, but those first 2 weeks or so can be a make or break thing with the nurse cows especially the holstein crosses. I have less trouble with the jerseys, even with the higher butterfat, because they just don't make the quantity.