We used to feed hay to both holstein calves and beef calves, but after several bloating incidents in a short period of time, the vet suggested feeding wheat straw to them becuase they were bloating from the hay. We raise winter wheat for grain and then bale the straw that is left over for bedding and feed. Low in nutritional value, but also cheap.
They can bloat on grain or hay, and if they do, you need to do something. We used to catch them and stick a short piece of garden hose down their throat until it reached their stomach to allow the built up gas to release.(make sure it doesn't go down the windpipe) If the animal can't get up, you can take a pocketknife or other sharp object and stick the side of the animal where it is bloated at. If your are new at this, you might want to call your local vet. If you had it happen once restrict whatever is causing them to bloat. Make sure they have access to clean water and some people add salt to the feed to make them drink more water. They should come out of it if there is something done about it, and sometimes they are bloated, but not enough to cause a problem. Prevention is the best cure.
As far as when to sell them, it is up to you. I think if you have the opportunity to make more money by feeding them until they're ready for slaughter, but if your just starting out, then maybe you don't want the money tied up for so long or maybe you have trouble keeping them over winter. It is strictly up to you. They will however finish out heavier than beef will, and therefore it will take longer. Generally, it takes 15-18 months to finish a holstein from birth and they will usually be between 1400-1650. This will change however depending on how they are raised and fed.
How many steers can fit on 15 acres depends on where you live, what is in the pasture, and how much grain you intend to feed. We have a few holsteins on pasture at about 1.5 steers per acre of fescue. We have a self feeder out there with them though so they have grain in front of them the whole time. Before they go to a self feeder, they are introduced to grain a little at a time. Start them off slow. We start calves on grain before weaning so they usually don't have any problems with a self feeder. We grind shelled corn with a supplement from our local feed store. We are thinking about using corn gluten to lower prices, so look in your area and see what feeds are cheapest around you. Usually about 16% protein and it drops as the calves get bigger.
Last, we buy our bull calves at 3 days to one week old for $90 from a neighboring dairy farmer, so I don't know exactly what holstein feeder calves are bringing. Hope this it helpful.
