Animal Feed Overview

Introduction

Definition

Animal feed as a general term can be used to describe any food given to domestic animals that are raised for the purposes of either procuring their products or as household pets, although it is more specifically used to describe animal fodder.  Fodder is food grown for animals and specifically carried and fed to them, as opposed to forage which is consumed by animals in the pasture and field. 

Most animal feed is manufactured for swine, fish, poultry, and livestock.  Field grains make up the primary source of animal feed, especially maize and soybean.  Hay, straw, and silage are manufactured from forage material and are also considered a form of animal feed.  Other traditional sources of animal feed include household scraps and food byproducts from processes such as milling, brewing, and ethanol manufacturing.  Leftover material from peanuts, soy, and corn milling can be important sources of animal feed.  Brewer’s Spent Grains (BSG) is the primary waste product from brewing and has been used as a livestock feed. 

Distiller’s Dried Grains with Solubles (DDGS) are the byproducts of ethanol manufacturing for both gasoline and alcoholic beverages.  The manufacturing of DDGS has dramatically increased in recent years and it has become an efficient alternative to corn and soybean meal.  DDGS has a longer shelf-life than corn and soybean meals and comparable digestible energy and metabolizable energy to corn.  It is especially used in swine diets, with many producers using a 20% portion of DDGS. 

A very broad definition for types of animal feed is concentrates and roughages.  Concentrates consist of cereal grains, byproducts, and oil meals or cakes.  They are high in energy.  Grains used for concentrates include corn, oats, barley, sorghum, rye, and wheat.  Oil meals or cakes include soybean, canola, cottonseed, and peanuts.  Byproducts can be used from processing of sugar beets, sugarcane, animals, fish, and both BSG and DDGS.

Roughages are grass pasture or plant parts, such as grasses, hays, silage, root crops, straw, and cornstalks.  Poultry, swine, and fish are fed with concentrates.  The digestive requirements of livestock ruminants require a diet formulated mostly from roughages.

Feed Formulation, Compound Feed, and Manufacturing

Different animals have different nutritional needs and animal feed products are specifically formulated to meet these needs. Compound feed is animal feed that is blended from different raw materials and additives. It can be a mix of whole or processed grains, concentrates, and commercial feeds that are strictly formulated and labeled.

Animal feed, including pet food, is regulated by the FDA and requires proper sanitary preparations and labeling without containing adulterants. The main ingredients are typically feed grains and final products are manufactured as meal, pellets, or crumbles. There are over nine hundred agricultural ingredients and coproducts approved for use in animal feed in the United States. Compound feed can also include premixes, which are composed of microingredients such as vitamins, minerals, chemical preservatives, antibiotics, and fermentation products that are purchased for the purpose of blending into commercial rations. Farmers can purchase these products separately and mix them into their own grain to formulate rations for their animals.

The first compound feed products were manufactured in the early 20th century. In the 1950s, the understanding of the nutritional needs of animals increased through research and the benefits of feed formulation became more pronounced, leading to a rapid increase in the production of compound feed. Different species of animals have different nutritional requirements throughout their life stages and feed is specifically formulated to meet these requirements. It is also proven that the output of products from animals, especially in the case of milk from dairy cows, is directly proportional to receiving the proper nutrition, making feed formulation especially important.

Nutritionists formulate animal food to provide animals with the necessary nutrients for proper growth, development, and maintenance. Products are specifically designed to compensate for nutrients and supplements that may be missing from an animal’s natural diet, especially in the case of pet food. They are also designed to function as the sole source of nutrition for the animal.

According to the American Feed Industry Association (AFIA), there are four basic steps in the animal feed manufacturing process. The first is receiving raw ingredients. Feed mills get raw ingredients from suppliers that are weighted, tested, and analyzed for different nutrient to ensure their quality and safety.

The second is creating a formula using feed formulation. Nutritionists and scientists work together to formulate diets that meet nutritional requirements. This can be a complex process as different species have varying nutritional needs during different life cycles.

The third is the mixing and processing of ingredients. Products are created in mills according to the formulation recipe to make finished products.

The fourth is packaging and labeling. Products prepared for retail are packaged with a label that includes the product’s purpose, ingredients, and instructions. Products prepared for commercial use are shipped in bulk. Quality assurance testing is done throughout the manufacturing process from the examination of raw materials upon arrival at the mill to monitoring in the mill to finished product final analysis.

Parameters of interest in animal feed that are tested for include moisture, protein, carbohydrates, fat, fiber, mycotoxins, and pathogens. There are a number of inherent challenges in quality assurance testing for animal feed, especially when considering the large variation that can be present in shipments of natural agricultural products. As advances in animal feed manufacturing and products continue to move forward, there will be more of a need for fast, non-invasive quality assurance testing methods that can test parameters of interest on a large scale basis.

Market Analysis and Regulations

The global animal feed market is expected to grow from $345.4 billion in 2020 to $460.3 billion in 2026 at a CAGR of 4.9%. It can be categorized into multiple smaller segments by form, region, and species for analysis. Examples of form segments include crumbles, mash, meal, and pellets. Species segments include swine, poultry, fish, and livestock.

The cost of feed makes up a substantial portion of raising these animals. In the case of swine and chicken, feed makes up approximately 60% to 80% of the total cost of production. Growth is anticipated to be supported by expansion into untapped markets and favorable policies across regional markets over the forecast period. Expected demand for innovative products should also fuel market growth.

Factors that may hamper growth include unstable raw material prices and a weak supply chain, although the market is expected to rebound from the negative impact caused by COVID-19 restrictions. There has been a marked consumer shift toward vegan-based diets and alternative protein sources to meat and dairy products, but there is also a large increase in demand for livestock products as well as a surge in industrial livestock production which has escalated the demand for high-grade animal meat products.

Industrial livestock production has undergone substantial transformation in terms of production and administration, mostly owing to technological advancements in animal vaccinations and antibiotics. According to the Food and Agricultural Organization, industrial livestock production now accounts for more than half the world’s pork and poultry, one-tenth of beef and mutton, and more than two-thirds of its egg supply. The shift from grazing and mixed farming to industrial livestock production is only expected to increase with increased population and a projected increase in the global demand for food by the United Nations of over 50% by 2050. Estimates indicate that global meat production will grow by approximately 70%, aquaculture food by approximately 90%, and dairy production by approximately 55% over this timeframe. If these projections hold up, there will continue to be a surge in demand as well as market size and value increase for animal feed products in coming years.

The Food and Drug Administration (FDA) regulates food for animals in the same manner as food for humans. In 1906, Congress enacted the Federal Pure Food and Drug Act, which gave federal officials the authority to regulate feeds shipped in interstate commerce. The Federal Food, Drug, and Cosmetic Act gave the FDA the authority to regulate food as “any food for man or animals”, making the approval process for feed ingredients similar to that of human food. The FDA is still the primary regulator of the animal food industry, although there are other regulations related to workplace, environmental, transportation, trade, and agricultural compliance that are under the purview of other agencies.

Animal feed is extensively regulated at the state level as well. Although there can be considerable differences between feed laws in different states, commerce is aided by the American Feed Industry Association (AFIA). AFIA was created in 1909 and primarily exists to manage priority legislative and regulatory issues on behalf of its members. AFIA’s members include nearly seven hundred domestic and international companies that are involved in the animal feed and pet food industries. It also works with the Association of American Feed Control Officials, an association of state and federal agencies that are charged by law with regulating the sale and distribution of animal feeds and animal drugs.

One recent key piece of legislation impacting animal feed is the Food Safety Modernization Act (FSMA) in 2011, which provided the FDA with new authorities and requirements for both the human and animal food industries. Some of these include the promulgation of rules for preventative controls, development of performance standards, strengthening of administrative detention rules, and mandatory recall authority of adulterated products. Compliance of FSMA falls into adoption of Current Good Manufacturing Practices (CGMPs) and completion of a food safety plan that includes hazard analysis. Importers are required to meet U.S. safety standards and verify that foreign suppliers have adequate preventive controls to ensure food safety.

With all the regulations and rules required for proper compliance, animal feed manufacturers must continue to implement sound testing and quality control methods.

Swine Feed

The basic nutrients required for pig feed are crude protein, metabolizable energy, vitamins, minerals, and water. Swine rations are generally based on a ground cereal grain for carbohydrates, soybean meal, added minerals like calcium and phosphorus, and vitamins. Byproducts of milk, meats, and cereal grains are used as well. Antibiotics can also be added to fortify the feed. The most common formulation for diets contain corn and soybean meal.

Corn is the major energy source that is fed to pigs. Other grains used as an energy source include oats, barley, and wheat. These grains are typically harvested earlier than corn, allowing farmers to spread manure on fields before corn harvest. However, they usually have a smaller yield than corn in terms of bushels per acre and calories per bushel. Processing coproducts used as corn alternatives include vegetable oils, DDGS, corn gluten feed, and corn gluten meal.

DDGS has especially become a popular, economical, and widely available ingredient in swine diets. It contains approximately the same amount of digestible energy and metabolizable energy as corn. Many producers are including 20% DDGS in their swine diets. However, distilled by-products can have a large amount of variability in chemical and nutritional content. A study conducted by Iowa State indicated that the variability of fat in DDGS is five times of that in corn and the variability of protein is sixteen times of that in corn.

Soybean meal is the most common feed used to supply pigs with protein and amino acids. The amino acids of soybean meal complement the amino acids in corn very well. Alternatives to soybean meal include whole soybeans, field peas, alfalfa meal, canola meal, linseed meal, sunflower meal, whey, and fish meal. However, both fish meal and animal products are often prohibited from being used in feed. If whole soybeans are used, they must be cooked or extruded to make the amino acids available to the pig.

Depending on the feed, supplemental amino acids may need to be added. Lysine is an important acid for pig muscle growth and corn protein is low in lysine, requiring the addition of it in feed. Crystalline amino acids can also be added to corn as an alternative to soybean meal. While more expensive than soybean meal, they are also more digestible than other forms of amino acids and allow for more precise diet formulation. Crystalline amino acids also can be used to more precisely match amino acid content with the needs of the pig, enabling reduction of the overall crude protein content of the diet.

In the final product, fat quality is defined in terms of physical and nutritive characteristics and is directly related to the composition of feed. Soft fat is a major concern to meat processors as it can cause lower processing yields and reduced value of the product. It can become rancid with undesirable flavor quicker than normal fat and may be oily, a characteristic that is unappealing to most consumers. Diets with high levels of vegetable oil and fish oil may reduce pork fat firmness. Generally, pigs fed a corn-soybean meal diet will have good fat quality.

Swine can also consume human food waste, which is beneficial in terms of recycling food waste. While food no longer fit for human consumption can be fed to pigs, this process is regulated by marketing guidelines and state regulations. Swine producers must ensure compliance when feeding human food waste to pigs. From proper feed formulation to compliant manufacturing practices, there are a number of challenges when producing swine feed that require quality control testing for parameters of interest.

Fish Feed

Farmed fish eat specifically formulated pellet or granule feeds that are specifically designed to contain the required nutrients for both the health of the fish and of humans who consume fish. They provide nutrition in a stable and concentrated form, enabling efficient feed and maximizing growth in a healthy manner.

There are two classifications for farmed fish. Herbivorous fish eat mostly plant proteins such as soy or corn, vegetable oils, minerals, and vitamins. Carnivorous fish eat fish oils and proteins. The majority of fish farmed around the world today are carnivorous, such as Atlantic salmon, trout, sea bass, and turbot. Fishmeal and fish oil are often combined with vegetable proteins, cereal grains, vitamins and minerals in the manufacturing process. Wheat can also be used to bind the ingredients in the pellets.

Until the end of World War II, most fish farms used raw meat as food. In the early 1950’s, research began on dietary dry pellet formulations. Successful results showed improved conversion rates of food intake to production of fish and has led to the widespread use of fish pellets and granule today. Modern fish feed manufacturing grinds and mixes together the ingredients while also using an extruder in the production line.

The primary ingredients of fishmeal and fish oil come from the processing of fish that are caught in the wild, usually from species that are not suited for processing to be consumed by humans. Fisheries that produce such fish are often referred to as reduction fisheries. Fishmeal is a brown material similar in texture to flour that is made by cooking, pressing, drying, and grinding the fish. Fish oil is a byproduct of this process that is not only a rich source of energy and fatty acids for fish, but also contains omega-3 fatty acids that have health benefits for humans as well. Soybean meal has been examined as an alternative to fishmeal in some feeds, showing good results in studies. Manufacturing is designed to hit precise quality targets in terms of size, durability, density, and nutritional composition while minimizing cost and maximizing resources.

The manufacturing process of fish feed begins with the grinding of the raw materials. Particle size has a strong effect on the feed digestibility of fish and is dependent on the milling process, making proper grinding essential. After grinding, the raw materials are mixed in a mixer. A feed extruder shapes the mixed raw materials into pellets by using a compression roller at a high temperature. This process ripens starch in the materials and congeals the proteins. Pellets are cut by knives at a specific length and conveyed out of the extruder at a fixed diameter. They are warm, wet, and soft at this point and must be dried and cooled.

Pellets are conveyed through a drying chamber on belts until reaching the optimum moisture content. Finished pellets are sent to a packing machine for weighing, packing, and sealing before shipping. Dry feed pellets are stable for long periods of time and must have durability, high crushing strength to withstand weight pressure, and water-resistance. Advances in fish feed manufacturing have enabled the manufacture of pellets with very specific characteristics, such as floating fish feed, sinking fish feed, various shapes, textures, and flavor as well as being produced specifically for livestock or pet feed.

As advances in fish feed manufacturing continue to move forward, the need for new and alternative testing methods throughout the manufacturing process will continue to grow.

Poultry Feed

Feeding costs make up the major cost in raising poultry and can account for up to 75% of total cost. They require more feeding than any other animals due to a faster growth rate and high rate of productivity. Poultry feed is typically manufactured in pellet form for a number of reasons, although some feeds are mash or are broken into granules after pellet manufacturing. Mash is generally used for baby chickens because it is easier to digest. Pellets are more convenient to farmers, enable the birds to eat more at a time, and have also shown improvement of feed conversion, decreased wastage, and improved palatability in studies.

Feed formulation is used to determine the proper ratio of feed components in different life stages and include carbohydrates, fats, proteins, minerals, and vitamins. As with swine, corn and soybean meal are typically used for energy and protein sources. Carbohydrates come from grains like corn, wheat, and barley. Proteins provide essential amino acids for development of body tissues and come from soybean, canola, and corn gluten. Fats are required for fatty acids that enable membrane integrity and hormone synthesis. Mineral supplements are usually required in poultry feed as chickens require large amounts of calcium, phosphorus, chlorine, magnesium, potassium, and sodium. Vitamins are typically needed in lower dosages but supplements may still be required.

Other components that can be used in poultry feed include fish and meat meals, salt, supplemental lipids, and various non-nutritive additives. Meals are a good source of protein and amino acids and also contain bone, which adds calcium and potassium. Salt is typically added at 0.2% to 0.5% weight. Supplemental lipids can help increase energy utilization. Non-nutritive additives can include antibiotics to stimulate growth and control disease as well as antiparasitic, antioxidative, and antifungal compounds.

The pellet manufacturing process begins with the screening of raw materials and removal of impurities. Meal is fed into a hammer mill and crushed into fine powder. Material that does not need to be crushed can be fed directly into the mixer with the meal. After mixing, the material is fed evenly and continuously into a pellet machine which discharges hot and soft pellets onto a belt conveyor. Pellets are cooled in a cooling machine and packaged. This process is conducted to make specific recipes for poultry feed composed using feed formulation. Feed is designed for good nutrition, minimization of resources and raw materials, high quality, and ultimately to make a product that meets nutritional requirements with the highest economic benefits.

Typical poultry diets include starter diets, broiler diets, and growing and finishing diets. Starter diets are fed in the first two to three weeks to chickens and the first two to four weeks to turkeys. They typically have higher energy content and higher doses of antibiotics to reduce mortality and stimulate growth. Broiler diets have higher vitamin supplementation, added fat, and adjusted protein content to maintain an optimum protein to calorie ratio. Growing and finishing diets have a varying crude protein content based on age range.

As advances continue in poultry feed formulation and manufacturing, more innovative testing methods will be required to properly make high quality products.

Livestock Feed

Livestock feed is feed fed to beef cattle, dairy cattle, horses, goats, sheep, and llamas. Nutritional requirements of livestock feed vary greatly based on the species, age, sex, breed, and environment of the animal. Basic nutritional requirements consist of protein, carbohydrates, vitamins, and minerals.

Unlike swine, fish, and poultry, livestock are ruminant species and digestive requirements dictate that a proportion of food consumed by them is forages. Pure grain diets cannot be properly digested by ruminant species. It is recommended that a minimum of 50% of a horse’s diet be some type of forage. While many livestock are raised on farms where they can purely consume forage in the field, there has been a marked shift towards industrial livestock production in recent years which has raised demand for livestock feed. In theory, a mix of fine and coarse particles in feed is ideal as finer particles are easier to digest in the rumen while coarse particles can increase the amount of starch entering the small intestine, increasing energetic efficiency.

The output of livestock animal products is directly proportional to nutritional intake, especially in the case of dairy cows. There are terms for the ways cows are fed and much debate over whether cows should be fed purely with grass or with supplements of grain and other foods. Cattle raised on primarily forage are labeled “grass-fed” or “pasture-raised” and similar terms exist for their dairy and meat products. “Free range” indicates the cattle reside in a field or pasture, but has nothing to do with their diet and this is often confusing to consumers.

Dairy cattle typically need more energy in their feed than beef cattle. Carbohydrate sources for dairy cattle include non-fiber carbohydrates (NFC) such as fermentable feeds and neutral detergent fiber (NDF) such as forage plants. High NDF content is good for digestive health but provides less energy than NFC sources. Fats can be added to livestock feed to increase energy concentration, especially when NFC content is high. Nutritionists use feed formulation to carefully plan the correct proportions of protein, fiber, carbohydrates, vitamins, and minerals. Up to one hundred pounds of rations can be consumed by a dairy cow per day. Corn and soybean meal are used for protein. Forage is used for fiber. Cattle require some salt and plenty of both calcium and phosphorus, often obtained from limestone and steamed bone meal. Rations are adjusted on the basis of the cow’s age and the stage of the breeding/milking cycle.

Livestock feed pellets are made using a process similar to other animal feed manufacturing processes. Raw materials are crushed and separated using a sieve. Materials are mixed in a feed mixer. Fatty ingredients are added to the material per the feed formulation requirements and the feed obtained from the mixer is often blended with molasses. Pellets are formed in a pellet mill, dried and cooled, and packaged for shipment.

The demand for meat products is expected to surge in coming years, which will only increase the need for industrial livestock production and subsequently, manufactured animal feed. There will be a need for new and innovative testing methods of parameters of interest in livestock feed as demand increases for products.

Animal Feed and NIR Spectroscopy

NIR spectroscopy has emerged as a fast, non-invasive testing method for parameters of interest in animal feed quality control. It offers the advantages of little to no sample preparation, the ability to be used for large-scale testing, and is able to determine multiple parameters with a single measurement.

The use of NIR spectroscopy has evolved from research and development studies in the animal feed industry to being used extensively by many large companies in the animal feed, animal forage, and pet food industries. Examples of macronutrients and energy components that can be determined using NIR spectroscopy include dry matter, crude protein, fiber, crude fat, carbohydrates, ash, metabolizable energy, and gross energy.

NIR spectroscopy can be used for analysis from the beginning to the end of the animal feed manufacturing process. It is used for raw material ID and component analysis as well as a tool for checking variation and shipment within batches. It is used as a real-time process control tool in the feed mill. NIR spectroscopy is also an aid for feed formulation by both determining variation in materials and giving manufacturers the ability to make mixing adjustments on the fly. When products are finished, NIR spectroscopy can be used for the final quality control check.

While the principles of NIR spectroscopy have been well-known for many years, recent technological advances have enabled its advancement as a practical tool in industry. Handheld and portable instruments have enabled analysis in the field. NIR spectroscopy requires the creation of calibration models to correlate NIR spectra to parameters of interest. Companies have created pre-built calibration models for parameters of interest, reducing both the labor and costs required to implement NIR spectroscopy. Third-party programs have enabled the use of web-based technology that supports database management, quality control, and trend analysis to optimize processes and protocols for animal feed analysis.

Research and development for new technologies and products is ongoing. As the worldwide demand for food continues to increase in coming years, NIR spectroscopy will play an essential role in many segments of the food industry, including animal feed.