Before you jump into something, why not go to the place you are thinking on buying your feed and having their feed specialist actually come out to talk to you about this.
While there is a good number of people on this board that are up on nutrition, the best and in my opinion - the only way - to do this for sure - is to actually sit down with someone who specializes in this and actually formulate a ration that works.
We do this on a regular basis - it costs nothing but your time.
You will learn what your costs are going to be.
You will get an idea of the expected weight gain.
You can add in all the other costs that you will incur - meds, penning, bedding and such.
And you can estimate a potential profit.
By the end of the discussion with the person who actually SEES your operation you will be able to make an informed decision on whether or not it is worth taking the risk.
And further more, if you maintain this relationship, as the animals grow you can adjust the feed program - which you SHOULD anyways -by utilizing the expertise of that feed specialist - to actually create a better feed for the animal as it matures.
Or, you can simply wait here for someone to tell you their opinion on feed.
Like I just did.
LOL
Bez