Derived from complex combinations of different amino acids, proteins are required on a regular basis for maintenance, particularly in milk production and muscle development. The amino acids are absorbed in the small intestine through the digestion of ingested food. Typical protein suppliers are oilseed meals (i.e. soybean, canola, flax), corn gluten meal, and urea. Soybean meal (pictured above) is a common oilseed meal, and it's a by-product from the extraction of soybean oil. In general, soybeans are cracked, oil is extracted and the remaining flakes are dried/roasted then crushed. The digestibility value of soybean meal increases with the amount of processing (heating, mechanical and chemical treatments). The photo below shows whole soybeans.