Animal Forage Overview

Introduction

Definition

Animal forage is plant material eaten by grazing livestock. Forage is consumed by both beef and dairy cattle, sheep, goats, and horses raised as livestock and also by animals in the wild. The term traditionally means only plants eaten directly in the pasture, but it can also be used to describe plants that are cut, processed, and fed to the animals as fodder, such as hay and silage. By definition, separated grain from plants is not a part of forage and forage can also include crop residue left in the field after harvesting and whole immature cereal crops.

“Forage crop” is specific to annual or biennial crops that are grown to be utilized by grazing or harvesting as a whole crop. Browse refers to the leaf and twig growth of shrubs, woody vines, trees, cacti, and other non-herbaceous vegetation that can be consumed by animals. Mast is the fruit and seed portion of non-herbaceous vegetation. Herbage is the biomass of herbaceous plants (except for separated grain) that is generally the above ground portion but can also include edible roots and tubers.

The two primary plant types used for animal forage are grasses and legumes. Forage grasses can be annual or perennial, summer or winter growing, and tropical or temperate. Grasses have many long, slender leaves that are borne on a stem. Their fibrous roots help bind the soil together and reduce erosion. Some grasses have underground stems known as rhizomes that produce new shoots at each node. Grasses without rhizomes are known as bunch grasses. Common types of forage grass include Bermudagrass, bromegrass, orchardgrass, canarygrass, timothy, tall and meadow fescue, Kentucky bluegrass, annual and perennial ryegrass, and switchgrass.

Most forage legumes have taproots and large, compound leaves that are arranged alternately on the stem. New shoots originate from the crown of the plant and the growing point of each shoot is located at the top of the shoot. Common types of forage legumes include alfalfa, birdsfoot trefoil, crimson clover, red clover, sweet clover, white clover, and lespedeza. Both grass and legume forages can be processed into hay or silage.

There are many factors that influence the nutrient content of grass and legumes as well as advantages and disadvantages for each type. Plant species, soil composition, plant maturity, and weather all affect nutrient content. Harvesting and curing affect nutrient content of hay. Grasses have more structure to the plant while legumes have more leafiness. Because of this, grasses have more digestible fiber while legumes have more protein, energy, and micronutrients. Grasses are also easier to establish in pastures and are more abundant in most areas of the world. They also tend to have longer growing seasons, are better suited to grow in poor soil, help with erosion control, and respond well to fertilization when being made into silage.

However, legumes are generally seen as superior due to their nutrient density and tendency to improve the soils they are grown in. Nearly all legumes are able to convert atmospheric nitrogen into plant-available nitrogen through Rhizobium bacteria in root nodules. Nitrogen fixation by legumes is good for soil, lowers cost of fertilizer, and gives legumes high protein content.

Many types of livestock get their ideal nutritional content from a combination of forage types with additional supplemental grain feed, especially industrial livestock. The feed formulation process enables manufacturers and farmers to mix different types of feed and forage to best suit the nutritional needs of the animal. In the case of forage, proper field management is crucial for animals who feed purely from grazing and forage will continue to play a crucial role in the health of animals and the environment all over the world.

Market Analysis and Regulations

The forage feed market is projected to grow at a CAGR of 8.1% until 2025. The market is comprised of grasses, legumes, hay, silage, and extracted material from harvested crops that are used to provide nutrition for livestock. While forage is primarily used for ruminant animals like dairy cattle, beef cattle, horses, sheep, and goats, it can also be fed to poultry and swine.

Livestock is one of the fastest growing sectors in agriculture and the demand for forage feeds in developed countries is growing rapidly due to urbanization, increasing wealth, and population growth. Market segments can be divided by products, animal species, or region. Products include stored forage and fresh forage. Animal types include ruminants, poultry, and swine.

Europe and North America account for 66% of the forage market. Oregon is the primary forage grass producing state in the United States and also produces a large amount of legumes. Area of cultivation is substantially increasing around the world, especially in Europe. On a global scale, the Canadian forage grasses timothy and bromegrass are the most widely produced grass forage. Alfalfa legume is the most highly traded forage and accounts for 27% of the forage market value in the United States. Developing countries such as China and India are anticipating a significant rise in demand in livestock production, meat consumption, and greater production in dairy products, making Asia-Pacific the market expected to see the highest growth over the forecast period.

Consumers have shown a preference for organic animal feed and the use of the terms “grass-fed” and “pasture-raised” for livestock dairy and meat products are appealing to consumers. Demand for milk is increasing around the world, thus increasing the demand for dairy cattle and forage as well. The nutritional value and diet of dairy cattle has a very strong effect on the quality of the milk product from them. Forages are the base ingredient for fiber and roughage and cows that are fed high quality forages, silages, and hay will not only produce good quality milk but more of it. As demand for milk continues to increase, the forage market will experience growth as well.

As is the case with animal feed and pet food, animal forage is regulated by the Food and Drug Administration (FDA) as well as at the state level. Products must be manufactured, packaged, and stored under sanitary conditions. Adulterated products that are mislabeled, contain filthy or decomposed ingredients, or are in any way subject to unsanitary conditions must be recalled.

The FDA’s Center for Veterinary Medicine (CVM) is responsible for the regulation of animal feed and forage products. Per the Federal Food, Drug, and Cosmetic Act (FD&C Act), any substance added to or expected to become a component of animal food must be used in accordance with a food additive regulation unless it is generally recognized as safe for that intended use (GRAS). Forages, grains, and most minerals and vitamins fall under the GRAS standard. A list of approved food additives for animal food is found in 21 CFR 573 and a partial list of GRAS substances is found in parts 582 and 584. A petition for approval of a new additive must address human food safety, target animal safety, environmental impact, utility (intended physical, nutritional, or other technical effect), manufacturing chemistry, labeling, and proposed regulation.

Labeling requirements at the federal and state levels must include brand name if there is one, product name, purpose statement, guaranteed analysis, ingredient list, directions for use, warning or caution statements, manufacturer information, and quantity statement. Implied claims that the intended use of a product to cure, treat, prevent, or mitigate disease as well as affect the structure or function of the body in a manner other than food (such as aroma and taste) must be proven safe and effective or be subject to regulatory action as an adulterated drug.

Grasses and Legumes

Grasses

Farmers have a number of factors to consider when choosing a pasture grass or mixture of grasses. These include annual rainfall, available water rights, soil types, and weed pressure. Management questions include the ability to rotate animals as well as mowing and spraying the pasture. Different types of livestock are best suited to different grasses so the livestock that will utilize the pasture in the present and future must be considered as well.

All grasses have distinct advantages and disadvantages that need to match up with available resources and management style. Kentucky bluegrass is a cool season, sod forming grass that goes dormant in the hot, dry part of the summer and has its best productivity in the spring and fall. It has good forage quality, withstands heavy traffic from animals in the field well, and tolerates close grazing. However, it has a relatively low yield of about two tons per acre and a minimum moisture requirement of 20” annually. Kentucky bluegrass mixes well with a short legume, such as clover.

Ryegrass can be both annual and perennial and are cool season, bunch-type grasses. They are high quality, easy to establish, can tolerate close grazing, and have a good yield of about six tons per acre. The disadvantage of ryegrasses is that they are weather sensitive. They are not overly tolerant to drought, heat, and cold, have a high moisture requirement of at least 30” of rain annually, need well-drained soil, and have poor shade tolerance.

Timothy is a perennial bunchgrass that can grow two to five feet in the seed head stage. It is primarily a hay plant but can be used for pasture when part of a mixture. It grows very well with alfalfa and red clover. While the first cutting has large yields, subsequent cuttings can show little regrowth and quality is greatly reduced when cut late.

Smooth brome is a cool season grass that forms a dense sod by spreading rhizomes. While slow to establish, it is well-suited to drought, heat, and cold winter weather. The big disadvantage of brome grasses is that they are very sensitive to grazing when the stems are elongating. Grazing is best when the plants are in between four and six inches or after they reach ten inches. Grazing when the plant is less than four inches may damage the plant.

Types of wheatgrasses include intermediate, tall, and crested. Intermediate wheatgrass is a cool season, sod-forming, and drought tolerant grass. Tall wheatgrass is a tall and vigorous bunch grass that is well adapted to saline and alkaline soil conditions. It grows best with 14” or more of annual moisture. Tall wheatgrass is non-aggressive and should be used in seed mixes with one or two other species. Crested wheatgrass is very drought tolerant, handles cold and shade well, and grows well at high elevations. It is a medium height bunch grass that requires only 8” of annual moisture. Established stands of crested wheatgrass can last up to thirty years.

Orchardgrass is a cool season bunch grass that works well with a range of soils with adequate moisture. It establishes easily but does not have good tolerance to drought, heat, and winter cold. Orchardgrass matures early and can be interseeded into existing pasture by either no-till or frost seeding. It should be grazed frequently to maintain quality but grazing below four inches may damage the plant.

Hard fescues are cool season bunch grasses that are drought tolerance and have decent shade tolerance as well. They grow in clump formations and are salt tolerant. They can tolerate medium acid soils, making them better adapted to forest and foothill regions than open prairies. They will not grow well in saline or alkaline soils. While slow to develop, they do have good seedling vigor.

Sheep fescue is the most drought tolerant bunch of this group and forms a tough, persistent cover after it is established. Tall fescue is a cool season bunch grass that spreads from short rhizomes. It is very shade tolerant as well as to drought and flooding, but does not handle cold weather well. Tall fescue is well suited for interseeding into existing pasture by no-till or frost seeding and grows longer into the summer than other cool season grasses but has a low yield of less than two tons per acre.

Selection of the proper species or mix is a crucial step in pasture management. It is not only important to choose properly according to the environment, but also to choose to best suit the grazing animals’ nutritional needs. Proper testing of forage grasses for nutritional composition is very important, especially when considering the variation that can exist in natural products due to environmental factors. As demand for forage grasses continues to increase, there will be a need for new and innovative testing methods to determine parameters of interest.

Legumes

Along with grasses, legumes make up a substantial portion of animal forage species. While generally considered more nutritious than grasses, they can also be more difficult to grow and less tolerant to environmental and weather conditions. However, legumes do offer the advantage of converting atmospheric nitrogen into plant-available nitrogen through Rhizobium bacteria in the root nodules, increasing both protein content in the plant and nitrogen in the soil.

Alfalfa is the most frequently grown forage legume and is the highest-yielding perennial forage crop in many countries. It can be grown alone or in combination with different grass species. Alfalfa produces more protein per unit area than other forage legumes and can persist for three or more years in a well-managed pasture. Protein and energy levels are determined by stage of growth at the time of cutting and under normal conditions it can be cut multiple times during growing season. It requires well-drained and fertile soils, a pH above 6.1, and adequate fertility for optimum growth. There is a critical six week harvest window that must be observed to avoid winterkill.

Birdsfoot trefoil is a short-lived perennial legume that is tolerant of low fertility and pH. It is non-bloating, well adapted to soils with low drainage, and best suited for permanent pasture situations. Plants can be subject to crown rot and must be allowed to reseed each year to persist.

Red clover is a cool season, perennial legume with hairy stems. It is an erect, leafy plant that can grow two to three feet tall and stands can last two to three years. Yields are good the year after establishment but can be reduced in subsequent years. Red clover is typically grown in fields that are too wet or too acidic for alfalfa. It establishes strongly and can suppress the establishment of other legumes in a mixture. When used as a feed crop, it is much better suited for silage than hay because it is difficult to dry and can result in dusty or moldy hay.

White clover is a short-lived perennial that can reseed itself in pastures. All types of white clover have stolons, which are stems that creep on the ground. The roots are shallow and fibrous and develop from the nodes of the stolons. The plants are leafy and grow from eight to twelve inches tall. They work well when frost seeded or no-tilled into existing pastures to improve forage quality and yield. White clover is tolerant of a wide range of climatic conditions, especially cool and wet weather as well as being suited to frequent grazing. It grows poorly during the summer, has a low yield, and is not well-suited for hay.

Sweet clover is an upright, coarse-stemmed, biennial cool season legume that can grow from four to eight feet tall. It is primarily used as a cover crop for wildlife and if used as a feed crop, it must be managed carefully because sweet clover contains coumarin, which can reduce palatability and cause hemorrhaging in livestock. Lespedeza can be both annual and perennial.

Annual lespedeza is fine-stemmed and leafy with shallow taproots. It is a prolific seed producer that is especially productive during summer months, grows from one to two feet tall, and is tolerant of low fertility and acidic soils. However, the growing season is short, quality is greatly reduced after a frost or if the plant matures, and yield can be low. While annual lespedezas do reseed themselves, they may fail to reseed if they are overgrazed, the autumn season is dry, or if early frost occurs.

Perennial lespedezas are warm-season, deep rooted plants that grow from eighteen to forty inches tall. They are tolerant of drought, soil acidity, and low fertility. Many varieties have a high tannin content that can reduce digestibility and animal acceptance, but there are some low tannin varieties. They become stemmy and quality is reduced when fully matured and are not well-suited for hay production as leaf loss is high when raking and baling.

Selection of the proper species or mix is a crucial step in pasture management. It is not only important to choose properly according to the environment, but also to choose to best suit the grazing animals’ nutritional needs. Proper testing of forage legumes for nutritional composition is very important, especially when considering the variation that can exist in natural products due to environmental factors. As demand for forage legumes continues to increase, there will be a need for new and innovative testing methods to determine parameters of interest.

Hay and Silage

Hay

Hay is grass, legumes, or other herbaceous plants that have been cut and dried to be stored for use as animal feed. It is typically fed to large grazing ruminant livestock such as beef cattle, dairy cattle, horses, goats, and sheep but can also be fed to smaller domesticated animals like rabbits and guinea pigs. Swine can be fed hay but do not digest it as well as ruminant animals. Hay is used as animal fodder when there is not enough pasture for animal grazing, when weather conditions are too poor for grazing especially during winter months, or when lush pasture by itself is not suited for the health of the animal.

Increasing industrial livestock production has led to higher demand for hay that can be fed to animals in a stable or barn. It is very versatile for a number of reasons. A large number of crops can be made into hay and it can be stored for long periods of time with little loss of nutrients if properly transported and protected from weather. Hay can supply most nutrients needed by livestock and can be both fed and produced on a large or small scale. It can be harvested, stored, and fed by hand or produced and fed mechanically on an industrial scale.

There are a number of important factors that affect the quality of hay. The ultimate test of hay quality is the performance and output of the animals that consume it and their products. Quality hay must be palatable and consumable in adequate quantities by the animals as well as free of toxic components. After consumption of hay, it must be digestible with good nutrient content for the health of the animals.

The stage of maturity when hay is harvested is the most important factor in hay quality. As grasses and legumes advance from the vegetative to reproductive stage, they become higher in fiber and lignin content and lower in protein content, digestibility, and acceptability to livestock. Studies on both fescue and alfalfa hay have shown that an early hay cut results in much higher protein content and percent digestibility, increased intake, and also permits aftermath growth to begin at a time when the temperature and soil moisture are optimum for plant growth. After cutting and mowing, poor weather and handling conditions can lower quality. Rain can cause leaf loss and reduce nutrient content. Excessive sunlight can bleach hay and lower vitamin content.

Conditioning and drying are performed to reduce moisture to 20% before baling. Conditioners such as potassium carbonate or sodium carbonate can be sprayed to reduce drying time. Ideally, raking when hay is at about 40% moisture and baling before moisture is below 15% will produce good quality hay. It is important to apply effective preservatives at baling to prevent excessive heating and mold growth, usually buffered propionic acid. Hay can be safely baled at greater than 20% moisture for small bales and at 18% moisture for large packages.

Other crucial factors in hay production include soil fertility, plant species and varieties, and seedling rates and dates. High yields of hay can remove large amounts of nutrients from the soil. While legume plants are capable of fertilizing the soil from fixed atmospheric nitrogen, grass stands require added nitrogen after harvesting. Mixtures containing more than 25% legumes that produce nitrogen typically do not need added fertilization. Legume species and varieties normally are higher than grasses in total digestibility, rate of digestion, protein, minerals, and vitamins but grasses offer advantages as well, such as faster drying rates.

Often, the ideal diet for a hay consuming animal contains a mixture of both grass and legume hay. The most practical way to determine the nutrient content of hay is through forage nutritive analysis. Testing results can be used to assess quality and to determine the amount and type of supplementation needed for the desired level of animal production. The use of an instrument to obtain a core sample of hay has been one of the most reliable methods of getting a representative sample for nutritional analysis. However, large variation can exist even within the same batches of hay and standard testing methods are ill-suited for large-scale testing.

As the demand for livestock and hay increase, there will be a need for new and innovative testing methods that are suited to determine parameters of interest on a large scale.

Silage

Silage is a type of fodder that is made from green foliage crops which have been preserved by fermentation to the point of acidification. While similar to hay in that both are comprised of grass or legumes that are preserved for the purpose of feeding livestock, there are several distinctions.

Hay is dried and always has a moisture content lower than 20% while the moisture content of silage is between 40% and 60%. The higher moisture content allows silage to retain a higher percentage of nutrients than dry storage. The goal of silage production is to minimize biological degradation and conserve digestible nutrients. In order to accomplish this, oxygen must be eliminated and silage acidity must increase rapidly for lactic acid bacteria to grow and stabilize or “pickle” the silage.

There are four stages to silage production. The aerobic phase eliminates as much oxygen as possible from the crop. Crops are chopped and packed in silos. The amount of oxygen left is dependent on moisture content, silo filling time and packing, and the fineness of the chopped silage. Bacteria use up oxygen and convert it to carbon dioxide. The aerobic phase typically lasts a day but can be as short as a few hours. Poorly sealed and packed silos will result in higher silage fiber and lower energy.

The second phase is the lag phase. After the oxygen is used up in the aerobic phase, plant cells are broken down and used as food by bacteria. Enzymes break down complex carbohydrates into simpler sugars and plant proteins as well, making the proteins more soluble. Acidity increases and pH drops from around 6.5 to 6.7 at ensiling to between 5.5 and 5.7.

The third stage is the fermentation phase which begins two to three days after ensiling. At this stage, oxygen has been eliminated and the pH is low enough for lactic acid bacteria to grow. As lactic acid bacteria grow and multiply, homofermentative bacteria produce almost exclusively lactic acid which is desirable, while heterofermentative bacteria produce lactic acid, acetic acid, ethanol, and carbon dioxide. Homofermentative bacteria are desirable because they work faster. In well-preserved silage, at least 70% of the total acid should be lactic acid (or 3% to 6% on a dry matter basis). Different types of forage crops have varying suitability for silage production. For example, alfalfa silage is more difficult to ferment because it has a lower sugar content and higher acid buffering capacity, which is a measurement of the ability to resist a pH drop. Corn silage is easier to ensile for the opposite reasons as it contains more sugars and has a lower acid-buffering capacity.

The fourth stage is the stable phase which begins about two weeks after the beginning of the fermentation phase. Silage should reach a final low pH of between 4.3 to 4.5 for legumes and 3.8 to 4.0 for corn. Bacteria have stopped growing and the silage is preserved. It is important to prevent heating in silage before feeding to livestock. Bunk life is the term used to describe the period of time before silage begins to heat after exposure to oxygen from yeast, molds, and aerobic bacteria. It can range to less than an hour to as long as several days. Poor packing and sealing before transport will increase the aerobic bacteria in silage, shortening bunk life. Silage that had a good fermentation with a low pH will have a longer bunk life.

Proper testing of silage for nutritional composition is very important, especially when considering the variation that can exist in natural products due to environmental factors. As demand for silage continues to increase, there will be a need for new and innovative testing methods to determine parameters of interest.

Pasture Management

The goal of pasture management is to match the feeding requirements of grazing livestock to the amount of forage growing in the pasture where they are feeding. It is a complicated process but has a number of substantial benefits. Proper pasture management can improve forage yields, lower feed costs, and the quality of livestock products.

Pasture rotation is a key part of pasture management. Livestock should be rotated through a system of pastures rather than grazing continuously on one large pasture, resulting in more forage, less overgrazing, and reduced soil compaction. Dividing a large pasture into four to seven pastures is usually sufficient and this is best done in the spring after grass has reached a height of at least six inches.

Once grass is grazed down to four inches, livestock should be moved to a different pasture. If a pasture has a mixture of grasses and legumes, livestock should be monitored to ensure that they do not overeat the same plant over and over again. Ten to twenty-five day rotations are typical in the spring while rotations can be lengthened to twenty-five to thirty days in the late summer.

Overgrazing will destroy root systems and grass will be unable to replenish. This can occur when there are too many animals on too few acres or when animals are allowed to pasture all winter. Typically, forage growth is reduced from November to March and during these months animals should be confined to a holding area.

The bare spots resulting from overgrazing not only destroy forage plants, but they can encourage weed growth, soil erosion, and runoff of nutrients. Soils can also become compacted, reducing growing capacity and limiting the amount of water that can filter into the soil. Ideally, a minimum of three inches of growth should always be left on pasture forage for healthy replenishment and to allow vigorous plants to better compete with weed plants.

Other good techniques for proper pasture management include mowing and clipping, soil testing, aerating, and proper reseeding. Mowing and clipping pastures after grazing is beneficial if not all plants were consumed to the desired harvest height. It helps maintain plants in the vegetative growth stage where they are the most productive and nutritious and also helps prevent weed growth. Soil testing helps determine if pH is out of balance or if the soil is low on nutrients and is highly recommended in poorer pastures before reseeding.

Reseeding varieties should be chosen on the basis of maturity speed. An early maturing variety is desired for a pasture where animals can be moved on to in the early spring. If a pasture is too wet during the spring, a later maturing seed is desired. It is best to keep animals off pastures in wet winter months but if soil is already compacted, aeration is desired in the spring or early summer when grasses are actively growing and will fill in rapidly.

Ultimately, the goal of forage farming and proper pasture management is to provide the necessary nutrition to livestock to maximize both the output of products and the highest possible quality. In order to achieve this, proper testing must be conducted for nutritional and energy parameters of interest in forage products. Current testing methods are often impractical for large-scale testing and ill-suited for determining variation in natural agricultural products.

As the demand for forage products continues to increase, there will be a need for new and innovative testing methods to determine parameters of interest.

Animal Forage and NIR Spectroscopy

NIR spectroscopy has emerged as a fast, non-invasive testing method for parameters of interest in animal forage 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 light measurement. Numerous studies have been conducted examining the feasibility and benefits of NIR spectroscopy as a tool for forage analysis and pasture management. It is a proven method for measuring both nutritional and energy parameters in forage, such as dry matter, protein, carbohydrates, ash, acid detergent fiber, neutral detergent fiber, and digestibility parameters.

Using NIR spectroscopy as an alternative to expensive, time-consuming, and laborious wet chemical tests for measuring parameters of interest is not only beneficial, but expands the horizons of what forage analysis can be used for and thus the scope of benefits in such analysis.

One such example is using NIR spectroscopy for real-time pasture management as a tool to determine seasonal variations. A study was conducted in England that used NIR spectroscopy to determine seasonal changes in nutrient concentrations of different pasture types (permanent and temporary) used for grazing and silage production. The study also correlated pasture height and herbage cover to the nutritional composition of the pasture, as well as the monitored nutrients to each other. Such analysis would be very difficult and time-consuming if performed on the necessary scale by wet chemistry tests.

The determination of variation in nutritional and energy composition in forage analysis has been elusive using traditional methods and the benefits of using NIR spectroscopy for this cannot be understated. The process of feed formulation to determine the ideal nutritional composition for animal diets is proven to work and the output of animal products is directly proportional to the nutritional intake of the animal, especially in the case of dairy cows. A problem is that large variation in nutrient composition can exist within forage in different fields on the same farm, within the same field, and even within the same batches packaged for sale. Such variation not only impacts the quality of animal products but also the margin of profits from a livestock operation.

NIR spectroscopy has been used to determine variation in both feed and forage on the farm with subsequent economic analysis based on the actual nutrient cost saved or spent determined from the difference between estimated nutrient content and actual calculated value. The Return of Investment (ROI) benefits of using such analysis are enormous, especially when determining variation in protein content of feed and forage.

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 support database management, quality control, and trend analysis to optimize processes and protocols for animal forage analysis.

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