Backgrounding?
Cheaper the better - pasture and no inputs other than salt and mineral will probably be just fine.
Every ton of grain / hay you buy / every input you purchase / every trough or staple or nail or wire you buy / eats into your profit.
Simple math. Average 2 pounds per day growth on pasture for a 550 pounder. Cost of grain broken down to cost per pound - if you get another pound of gain per day - then how much have you gained?
You feed any 10 cows 5 pounds of grain per head per day - do they all get 5 pounds - nope. The aggressive eater gets 7 and the quiet eater gets 3. Unless of course you separate them - not efficient nor always easy. What is the cost of grain in your area? The cost of hay?
You have to figure the price you will receive when you sell them - how's your crystal ball gazing? - unless it is an agreed upon price in advance to a buyer.
Cost of pasture - even if it is yours there are costs - taxes / fertilizer / fences / weed control / mortgage if any / and so on.
Remember - you have to figure in time, fence fixing, hauling, feeding and so on. Lots more costs - equipment? Fuel? Supplies? Vet? etc ....
In the end in this part of the world if you have good pasture, water, some mineral and salt, the returns are actually better than throwing them in a lot and buying feed.
If you are doing this as a hobby and throwing home earned money at it - well, then the sky is the limit on what you might spend. And any good feed rep will be glad to help you spend your money.
Sharpen that pencil, break out the calculator and hope like heck the gods smile on you - lose a couple to disease / accident or whatever and you are now in the hole - no matter how sharp your pencil is.
Maybe different where you are, but I suspect not much. Good luck - hope you make a dollar.
Spend NO money that is not TRULY necessary to graze the animal.
Otherwise we can all sit down and tell you the best way to put weight on an animal. Lots of grain, free choice good hay, lots of clean water, 100% safe confinement, regular vet check for herd health, good shelter, and so on. That all costs.
So to close out - yup, weight gain is important and you wanted to know what to feed. In the end it should be your local ag rep, successful farmer neighbour, calculator and pencil that will tell you. But only after you research the potential input costs and have an accurate guesstimate on the price you will get for them when you sell them.
Long answer and not being snippy - keep them fed and they will grow. Have a great day.
Regards
Bez