Everyone is familiar with the word "protein", because it turns up so frequently in everything from food to shampoo. Whether we are dealing with commercial or backyard flocks, all poultry need protein in the feed. Because of its tremendous importance, it is worthwhile to gain a basic understanding of this important nutrient. The range of different substances that are composed of proteins is so varied it is difficult to remember we are talking about the same basic thing. To illustrate, animal tiss...ues as different from each other as meat, hair, hooves and nails, egg white, cells in the blood, leather and skin, and feathers are almost all solid protein. Plants, and especially seeds like corn and soybeans, contain protein, but are mixed with carbohydrates like sugars, starch, and fiber. The reason proteins can be so different from each other is that they are assembled out of 20 different building blocks, called amino acids. If we think about it, we can probably come up with a list of 20 different construction materials such as red bricks, cement blocks, concrete slabs, wooden beams, steel rods, and the like. While all are what we would call "building materials", they can be used to construct an astonishing variety of structures. The same is true with the 20 amino acids…there is no end to the different types of proteins that can be made from them. Here we should mention that all acids are not like the fuming flasks in Dr. Frankenstein's laboratory, and amino acids are not like that at all. They are simply white powders. The two most common that we add to poultry feeds are lysine and methionine.