Excuse me, but dont you think major brand distributors have done all the legwork for you? Multiple feed variations for which ever application of bird stock you are raising is pretty much available. If you only have egg birds, then there is layer feed. If its meat birds, etc. The real problem comes into play depending on the breed you have. Some require on this or that depending on what you are using them for. Some birds are lined with fat globules from improper feeding ratio blends while others fed the same feed are lean and sinuey. Some people feed their chickens a steady diet of crumbles or pellet feed with very little to no grain nutrient. IMO I think both are important but most crumble and pellet products dont contain all of what is in scratch blends. Scratch blends lack sufficient protein levels, but contain other valuable nutrients. If you find a layer feed with at least 19% protein, you can add 25% scratch and your birds should do very well.