The combined supply chains of the grain and poultry industries begin with inputs such as seeds, fertilizers, and chemicals that are used when planting grains. Inputs are either sourced formally from seed companies and seed associations or informally with farmers using saved seeds to avoid the high cost of certified seeds. As the below grains to poultry value chain diagram signifies, once the crops are harvested, they are taken to the market or bought directly by feed mill producers and poultry farmers. Other ingredients for animal feeds such as wheat offal and soybean meal are sourced from flour milling companies as they are byproducts of goods produced. Combinations of ingredients used in animal feeds differ depending on the age and nutritional requirement of the chicken.