Feed in agriculture refers to any material given to livestock and poultry to provide the nutrients they need to grow, reproduce, and stay healthy. It is the single largest expense in raising animals, typically accounting for 60% to 70% of total production costs in any given year. Global compound feed production now exceeds one billion tonnes annually, making it one of the largest segments of the agricultural economy.
What Feed Contains
All animal feed delivers six categories of nutrients: carbohydrates, fats, proteins, vitamins, minerals, and water. Carbohydrates and fats supply energy, proteins provide the building blocks for muscle and tissue growth, and vitamins and minerals support everything from bone development to immune function. The proportion of each nutrient varies depending on the animal species, its age, and whether it’s being raised for meat, milk, or eggs.
Water content matters more than most people realize. A fresh forage like grass silage can be over 60% moisture, meaning an animal has to eat a much larger volume to get the same nutrition it would from a drier feed. Nutritionists often compare feeds on a “dry matter” basis, stripping out the water weight so they can accurately compare the actual nutrient density of different ingredients.
Forages vs. Concentrates
Feeds broadly fall into two categories: forages (also called roughages) and concentrates. Understanding the difference is central to how farmers design diets for their animals.
Forages include hay, silage, pasture grass, and other high-fiber plant materials. They are bulky and take longer to break down in the digestive tract. In research comparing lamb diets, forage-based feeds contained roughly 643 grams of fiber per kilogram of dry matter, more than double the 278 grams found in concentrate feeds. That bulk physically limits how much an animal can eat in a day, because the gut fills up before the animal has consumed as many calories as it might from a denser feed.
Concentrates are energy-dense feeds like cereal grains (corn, barley, wheat), oilseed meals (soybean meal, canola meal), and commercial pellets. A typical cereal-based concentrate provides about 15% crude protein and significantly more calories per mouthful than forage. Animals on concentrate-heavy diets gain weight faster because they can digest the feed more quickly and extract more energy from a smaller volume. Most commercial livestock operations use a blend of both, adjusting the ratio based on the animal’s purpose and growth stage.
How Feed Is Manufactured
On small farms, feed might simply be grain mixed with minerals in a bin. At commercial scale, feed manufacturing is a precise industrial process. Raw ingredients are first ground or milled to a uniform particle size so they blend evenly. Vitamins, minerals, and any additives are then mixed in according to a specific formula.
The majority of livestock feed is processed through a pellet mill. Pelleting uses steam, pressure, and heat to compress the blended ingredients through a die, forming dense cylindrical pellets. Binders are usually added to keep the pellets from crumbling during transport and storage. Some specialty feeds, particularly for aquaculture and pet food, go through extrusion instead. Extrusion uses similar principles but operates at higher temperatures and pressures, which can alter the starch and protein structure of the feed to improve digestibility.
Pelleting offers practical advantages beyond nutrition. Pellets reduce dust, minimize ingredient separation during handling, and make it harder for animals to pick through and eat only their favorite components of a mixed diet.
Feed Additives and Their Roles
Beyond the basic nutrients, modern feeds often include additives that improve animal health or feed efficiency. These fall into several groups.
- Probiotics and beneficial bacteria: Live microorganisms, often strains of Bacillus or Lactobacillus, that colonize the gut and suppress harmful bacteria. They work by producing organic acids that lower gut pH, making the environment less hospitable to pathogens. Research in broiler chickens has shown probiotics can improve immune function, increase production of digestive enzymes, and enhance growth performance.
- Prebiotics: Non-digestible fibers that feed beneficial gut bacteria, helping them outcompete harmful species.
- Organic acids: Compounds that preserve feed quality and support gut health by inhibiting mold and bacterial growth.
- Phytogenic compounds: Plant-derived substances like essential oils and herb extracts that can have antimicrobial or anti-inflammatory effects.
- Clay minerals: Used as binders and to adsorb toxins in feed, though they can also interact with gut metabolism, so their use requires careful formulation.
Many of these additives have gained importance as alternatives to antibiotic growth promoters, which have been restricted or banned in numerous countries due to concerns about antibiotic resistance in humans.
Why Feed Costs Drive Meat Prices
When feed accounts for 60% to 70% of the cost of raising an animal, any fluctuation in grain or soybean prices ripples directly into the price of meat, milk, and eggs at the grocery store. Drought, trade disruptions, or increased demand for biofuels can all tighten the supply of feed grains and push livestock production costs sharply higher. This is why commodity corn and soybean prices are closely watched indicators for the entire food system, not just for crop farmers.
Feed efficiency, the amount of feed an animal needs to gain a pound of body weight, is one of the most important metrics in livestock production for exactly this reason. Genetics, feed formulation, and management practices all aim to improve this ratio, getting more meat or milk from less feed.
Regulation and Safety Standards
In the United States, animal feed is regulated under the Food Safety Modernization Act. Feed manufacturers are required to maintain a written food safety plan that identifies biological, chemical, and physical hazards and establishes preventive controls to minimize or prevent them. Facilities must conduct a formal hazard analysis and implement risk-based controls throughout their operation.
Supply chain oversight is a significant part of these regulations. Manufacturers must verify that raw materials come from approved suppliers, and any ingredient requiring a specific safety control in the supply chain can only be accepted after verification activities confirm it meets standards. These rules exist because contaminated feed can harm not just animals but also the humans who consume animal products, as certain toxins and pathogens can transfer through the food chain.
Insects and Alternative Protein Sources
The heavy reliance on soybean meal as the primary protein source in livestock feed has prompted research into alternatives with a smaller environmental footprint. Insect meal is one of the most studied options. Insects can be raised on organic waste streams, require far less land than soybean cultivation, and adapt easily to production in different climates and countries.
Research evaluating four insect species as feed for ruminants found protein content ranging from 81 to 112 grams per kilogram of dry matter. The protein showed moderate breakdown in the rumen (41% to 76%), consistently lower than soybean meal, and the portion that passed through to the intestine was well digested (at least 64%). These characteristics suggest insects could complement or partially replace soy in ruminant diets. Regulatory frameworks are still catching up, however, and in many regions insects are not yet authorized as feed ingredients for all livestock species.