What ARE Chickens Fed? We explore the basics.

Due to customer demand and a growing public interest, more often in supermarkets we are now seeing chicken labeled things like grain fed, pasture raised, free range; leaving shoppers wondering what the difference is? What are broiler chicken eating?

The chicken that ends up on our dinner plates are called broiler chickens. These are chickens that are bred and raised for meat. Today we are taking some of the scare out of it and discussing what goes into a broiler chicken’s diet.

Diet Composition

Broiler diets are composed primarily of a mixture of cereal grains, soybean meal, by-product meals, fats, and vitamin and mineral premixes. Together with water these feeds provide the energy and nutrients that are essential for broilers to maintain activities and the building blocks for their growing.

Nutrients in a diet can be divided into six components: carbohydrates, fats, proteins, minerals, vitamins, and water. Nutrient classes can be categorized as either macronutrients or micronutrients. Macronutrients are nutrients that the broilers need in large amounts, providing energy and building blocks for the maintenance and growing. Micronutrients are nutrients that broilers need in small amounts. Each of these compounds is important for broiler’s growth, production and maintaining health, and a deficit of even one can have serious health consequences.

The nutrient requirements of broiler chickens vary depending on factors such as genetics, species, breed, physiological status, age, gender, environment, and housing. The most convenient way to satisfy a broiler’s nutrient requirements is to provide a commercially balanced diet. Some producers mix their own diets to assure safe ingredients are used and specific nutrients for their flock. When using commercially balanced diets to feed your flocks, it is important to know the nutrients provided by the diet you have chosen. Likewise, it is important for producers who mix their own diet to be aware of the nutrients provided by the ingredients you are using.


Carbohydrates make up the largest portion in broiler diets. Carbohydrates are a major component of plants that make up 70-85% of the dry matter. They are generally presented as sugar, oligosaccharides, starch, cellulose, and non-starch polysaccharides in plants. Starch is one of the most important energy sources in a broiler diet. Both sugar and starch can be easily broken down by the digestive tract into glucose and is absorbed as a quick source of energy that is required in all cells.

Although these carbohydrates cannot be digested or utilized as energy sources for broilers, they play important roles in intestinal health. Too much of them, however, can cause intestinal problems and reduce the growth of broilers. Cereals grains such as corn, wheat, barley, sorghum, and rye are important energy feedstuffs in broiler diet. These feedstuffs are typically high in carbohydrates, especially starch, and low in crude fiber and crude protein, in this way they provide the cheapest source of energy for broilers.

Fats / Lipids

Fats are a type of lipid, a category of molecules united by their hydrophobic and nonpolar abilities, made up mostly of hydrocarbon chains. More than 95% of lipids in the diet are in the form of triglycerides, which are made up of three fatty acids attached to a glycerol backbone. These fatty acids have a high energy density per unit weight and make up the long-term storage of calories in animal body. Energy provided by fats, is 2.25 times higher than protein and carbohydrates. 

Common sources of supplemental fat in commercial balanced diets include animal fat such as tallow, lard, and poultry fat and vegetable oils such as corn oil, soy oil, and canola oil. Most vegetable oils consist mainly of unsaturated fatty acids, with proportions of linoleic or linolenic acid up to 60%. Animal fats contain both saturated and monounsaturated fatty acids.

Commercial broiler diets are formulated with high energy content with over 3,000 kcal per kilogram. Fats are generally added a range of 3-10% as a concentrated energy source to meet broiler chicken’s high energy requirement. Other than providing energy, fats also maintain the cell membrane integrity, provide building blocks for hormones, and act as a carrier of fat-soluble vitamins that require fat for absorption. The addition of fats also improves its palatability and pellet quality of chicken diets.

While chickens do not have a requirement for fats, they do have requirements for essential fatty acids. Essential fatty acids need to be supplied through diets because of an inability of broiler to synthesize them. Linoleic has proven to be a requirement in poultry as impairments result in growth and immune system functions. In male birds, deficiency symptoms also result in effects in their ability to mate. With this in mind, the essential fatty acid amount required is very low and deficiency is rarely observed in broilers fed commercial balanced diets.


Proteins are a large complex organic compound made up of amino acids. When a protein is ingested by broilers, the digestive process breaks down proteins into amino acids. Amino acids are then absorbed and transported to cells and converted into the specific proteins that required by the broiler chickens. Unlike carbohydrates and fats, proteins do not serve as a direct energy source. They work like building blocks for other structures in the body and function as hormones involved in metabolic, transport, and hormone systems, as enzymes regulate metabolism, as antibody in the immune system, and maintain balance in the body. Failure to provide adequate protein in a broiler’s diet results in a number of structural health problems, and stunts growth.

Sufficient protein must be supplied in broiler diets to ensure adequate amino acid synthesis. Amino acids can typically be divided into two classes: essential and nonessential. Essential amino acids are those that cannot naturally be made in adequate amounts to meet the needs of a broiler. Non-essential amino acids are those that can be generated in sufficient amounts when precursor material is available. There are twenty-two amino acids commonly found in feed ingredients. Of these, eleven are essential and must be supplied in the feed. When a commercially balanced diet is formulated, a variety of feedstuffs with high protein content are included because no single feedstuff can provide all the necessary amino acids in the right levels for broilers.

The main sources of protein in broiler diets are plant proteins including soybean meal, canola meal, cottonseed meal, palm kernel meal, and corn gluten meal. However, the label on a bag of commercially balanced diets lists only the percentage of crude protein, an approximate amount of protein that is calculated from the determined nitrogen content contained in the diet. This information does not indicate the quality of the protein used. Protein quality is based on the digestibility of crude protein, the profile of essential amino acid. Dietary proteins not containing the correct proportion of amino acids will be utilized inefficiently. For broilers living on a corn and soybean meal diet, the most common combination used chickens are commonly deficient in methionine and lysine. Deficiencies of either methionine or lysine will lead to a significant drop in productivity and the health of broilers. To combat deficiency, commercial balanced diets typically contain purified crystalline of methionine and lysine supplements.


Required in large amounts, water is the most neglected nutrients. Commercially balanced diets generally contain only 10 to 12% of water, which is an extremely important part in broiler nutrition. It makes up 80% of a broiler’s body weight. As the highest single constituent of the body, water plays a crucial role in every metabolic and physiological function occurring throughout the body. Water aids in the transportation of nutrients from the digestive tract to cells and carries waste to the liver and kidneys. It conducts gases, transports hormones, and is responsible for maintaining homeostasis. Water also helps broilers to regulate their body temperature. Without adequate water, broilers are not able to cool their body temperature during heat stress. A 10% loss of body water will cause severe dehydration and result in further death. Therefore, adequate availability of water is critical for maintaining health and performance for broilers. There is no precise water requirement for broilers, however, because the drinking behavior is directly related with feed intake. The quantity of water consumed by broilers is approximately 1.6 to 2.0 times of feed intake on a weight basis. Water intake can also be influenced by numerous factors including physiological status, environment, diet, and water quality. It is therefore necessary to provide broilers with adequate drinking water and keep water is always accessible to them to satisfy their daily need.



Hopefully this takes some of the mystery out of the question, and sheds some light on what chickens need be they organically fed, pasture raise, or even raised in you own backyard. While we all have our presences on what kind of chicken we consume we can all agree that a balanced and nutrient fulfilling diet is best for all broiler chickens.

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