Assuming your show date is Feburary 1, 2002. Divide 200 by 123 and this will mean your pig will need to gain 1.63 pounds per day. I suggest at least once per month. This is very important because if changes in your feeding rate needs to be made you can do this before the last few days before show and prevent your pig from looking poorly at show time. It is also important to make sure clean, fresh, cool water is always available to you animal.
Exercise is also important.
You are about to start a very exciting and rewarding project. We wish you much success. David I m not sure what you are trying to determine. The only think I can suggest is to take the cost of the grain and divide by the percent protein. Please remember small grains are not fed for their protein value but rather their energy value.