Couple of thoughts. I have been involved with dairy in different capacities for many many years. All cattle wind up as beef eventually.
As far as the dairy replacements....there are people who custom raise the heifers and it was a decent way to go but not so much now. Most dairies want their own calves as their replacements except for the mega dairies that buy springers. It costs more than what a dairy heifer will bring now, to raise her to ready-to-calve. The milk market is dropping again and the cost to get a heifer raised up to calve is $1500 to 2000. Right now if a farmer can get 1200 to 1500 for his extra females he is doing good. There will be another bunch of dairy farmers going out if the drop in milk prices continue. Many are getting older and are finally getting to the point of why keep fighting it when you can barely pay the bills on a good month. Younger farmers are realizing that it is too much work and headaches to keep butting up against the gov't price controls and regulations with no real return for your life being tied to it.
If taking thin/undernourished calves and raising them up was profitable most of us would be doing it. Most of us that have been in the cattle business for awhile get shut of the thin poor performing ones because we know they will never make the grade and it is throwing good money after bad. Most don't let the cattle get to that point to start with, as we know the small margin of making money on good healthy well performing cattle.
A niche market of raising cattle to sell as beef is one but you have to know how to feed and FINISH an animal in order for it to make good beef on the plate.
Sheep or goats are a good market. Lambs and kids in the 40-80 lb range are sought for the different ethnic holidays and can be very profitable. BUT, they are going to slaughter....if you are having a hard time with the idea of cattle for beef, how will you feel about that cute goat kid or little lamb going to meat at a young age? Plus the requirements of fencing for sheep and goats is a whole other level than fencing for cattle. Plus there is the predator problem that sheep and goats face that most cattle don't. Dogs, COYOTES, and others prey on baby lambs and goats that cattle people don't have as much worry about.
I am not trying to be negative. We have beef and a few dairy cattle. Raise about 50-60 ewes and sell lambs. Have had hogs, and have chickens now and fight with a myriad of predators for each different class of animals. Go years with no problems then have a year from he// with everything that can go wrong does go wrong. You need to maybe try to apprentice with an established farm in the area and get a taste of the day to day before you go to committing. We have managed several places for "WANNABE FARMERS" ; converted suburban people who thought they were going to come to the country and make all kinds of money and raise all these wonderful animals and breed rare breeds and to find out that it just isn't that rosy glow picture. The money that goes into a start up operation is staggering, and the return is small. You have to really "have the fire in the belly" to believe in and want to do this and realize that 75% of all the farmers in this world now hold an outside job or have a spouse that does just in order to make ends meet. Add in more gov't requirements of insurance....
You need to start out raising your own food, meat, and such and see what it takes to just keep yourself in food, and the time and effort to keep it going. Get some real time experience and then make the CHOICE to go bigger. Spend some time at the stockyards/sales barns. See what real life prices are. It takes 18 -30 months from birth to get an animal up to size to kill for beef. Sheep/goats are 6-12 months to a decent weight of 80 + lbs.. Pigs 6-10 months to 250 lbs for butcher
size. Turkeys are 14-24 weeks, Chickens 42 days for the confinement house to broiler size, 6 months for the average backyarder raising them for their own meat. A commercial poultry house, with all the regulations and contracts to companies, will run in the HALF MILLION dollar investment per house. You get paid for your time and do things their way because they have the investment in the birds and the feed.
Really do some serious research so you really know what you are getting into. It can be done, but don't expect it to make you alot of money.
