I would like to learn about supplementary feeds or how to prepare cheaper local feeds for my rainbow roosters
Cheap is relative depending on how available the raw materials are in your area of operation. It is thus worth doing market survey on the availability of the following ingredients maize germ, wheat bran, sunflower cake, cotton seed cake, rice polish, fish meal. Once done confirm from agro-dealers too availability of poultry premix. Should you find this readily available, then you can now think of formulating your own feed. On supplimentation, you could use greens and other cheaper ingredients especially energy and vitamin source but be careful not to let that be entry point for disease causing microorganisms. Bottom line is one should understand when the birds are more of liability than asset and make sound economic decision.