By Terrell Spencer, NCAT Agriculture Specialist

This publication explores the important role that forages play in pastured poultry production for either meat or egg production. Research on the effects of raising poultry on pasture has increased greatly in recent times, with an ever-growing body of scientific work. This publication pays special attention to the nutritional benefits of poultry foraging on pasture: regarding both the birds’ health and the impact that forages have on the nutritional and flavor qualities of the meat and eggs.

Laying hens, both commercial and heritage breeds, are enthusiastic foragers on pasture. Photo NCAT

Contents

Introduction
Advantages of Forage Consumption by Poultry
Forage Impacts on Poultry Meat and Egg Quality
Factors Affecting Forage Consumption
Insects and Other Animals as Forages
Utilizing Native Pastures
Establishing Poultry Pastures
Protecting Pasture from Poultry
References
Appendix 1: Sprouted Oats

Introduction: Forage’s Historical Role in Poultry Rations

Raising poultry on pasture is a time-established method of farming quality chickens, turkeys, waterfowl, and other poultry. Historically, before the maturation of poultry
nutritional science and the widespread availability of balanced rations, forages were an important component of poultry diets. Access to vegetation was a way of providing a multitude of critical vitamins and minerals, many unknown until the middle of the 20th century, to meet a flock’s nutritional needs. The importance of the vegetation that poultry consumed while on pasture can be seen in the following excerpt from a 1930 poultry-production textbook:

“At all times of the year, an abundance of green feed is necessary. A lack of it is often a cause of ill health and low production. It acts as a tonic in functioning properly, securing for the bird a larger utilization of the feed consumed. The principal value, therefore, is in maintenance of health. The importance of abundance, as well as a variety, of green feed is seldom fully realized.” (Rice and Botsford, 1930)

For hundreds of years, small farm flocks were allowed to roam and scavenge most of their diet from a farm’s pastures, barnyards, orchards, and fields, with occasional supplementation from scratch grains and table and garden scraps. The leaves and seeds the birds ingested, as well as the insects that were quickly gobbled up (often full of freshly consumed plant matter), helped balance out any of the unknown deficiencies in the feed ration. Indeed, before the middle of the 20th century, forages were the only reliable source for necessary nutrients like vitamin A, critical in preventing devastating diseases.

As poultry farms grew larger as the 20th century progressed, the ways that farmers incorporated greens into the diets of their birds were as varied as the farmers themselves. Many farmers would let their flocks freely graze around the colony houses/coops where the hens lived and laid their eggs. Where climate, space, and economics allowed, other farmers would plant grains such as barley, oats, or winter wheat for the birds to graze while the grains were young and still appetizing. This
practice was especially helpful in the winter, when few other forages were present. Similarly, some farmers managed poultry-friendly pastures— filled with ryegrass, clovers, or other highly palatable forages—for laying flocks. By midsummer, when the flocks had consumed most of the available forages and the invertebrate populations become scarce, greens or fodder crops would be supplied from a truck patch or even garden pickings. On many farms, greens—primarily kale — were grown specifically to harvest as poultry food. Reviewing old poultry accounts, one variety of kale is frequently referenced: 1,000-headed kale. This kale was prized by many poultry farmers over other greens due to its prolific and hardy nature. Plants could easily approach six feet tall, and the large leaves were harvested as needed in a “cut and come again” fashion.

Lavelle Donovan, who grew up on a poultry farm in California in the 1920s, recalls:

“Chicken greens were kale or a low vine called rape which was cut with a scythe. I can still see my father in the kale patch. He’d pick a kale leaf and tuck it under his arm until he collected a bunch. Then he’d put the bunch in a burlap bag he dragged along tied to his waist. Then he chopped up the leaves with the kale cutter in the barn.” (Lowry, 1993)

The larger and more confinement-based the farm, the more greens were needed. The largest farms grew at least a couple of acres of kale and other greens, usually transplanted by hand, for their poultry rations.

Other farmers used different strategies to get greens into their flocks when forages became scarce. Supplementing rations with green additions like alfalfa or grass meal (a strategy still well-advised today) was considered essential to provide sources of unidentified nutrients (Blair, 2008). Sprouted grains such as oats or wheat (see Appendix 1 – Oat Sprouter), or vegetables like kale and cabbage, were also fed to the flock at regular intervals. Feeding rootstocks like mangels (a type of large beet for livestock) or carrots during the winter, along with winter-hardy greens, was a routine practice, providing a nutritional boost and also helping to reduce excessive pecking in flocks during the winter by keeping the hens preoccupied.

Advantages of Forage Consumption by Poultry

Feed Savings 

Forages can provide a significant amount of poultry nutrition, reducing the amount of feed that a poultry farmer feeds a flock. Although poultry are NOT ruminants (they’re omnivores), a good pasture is still a valuable resource for the flock. Jeff Mattocks, a livestock nutritionist with decades of experience in pasture-based and sustainable/organic farming, estimates that after “gathering data from year to year and producer to producer, I have come to the conclusion that pastured poultry eat 5-20% (of their diet) from pasture, depending on type and age of poultry, and the quality of forage growth” (2002).

In many areas, feed savings are typically greatest in the late spring and early fall, when lush pasture provides plenty of high-quality forages to offset a significant amount of the cost of feeding poultry. Additionally, insect and other invertebrate populations (poultry favorites) in the pasture are booming at the same time. The amount of plant forages consumed by the flock, or even an individual bird, depends on a variety of factors that will be further explored below.

Nutrition Source

The primary benefit of forage consumption is that plant matter is typically high in both vitamins and minerals. Besides the vitamins and minerals, forages also contain components such as fiber, protein, energy (calories), and other compounds like carentoids and Omega-3 fatty acids that are important for metabolic functions in all animals, especially humans. The specific benefits that poultry gain from forages are explored below for each nutritional group.

Vitamins

Vitamins are complex organic compounds required by animals for normal growth. Many of the vitamins added to modern-day poultry rations can lose their potency over time because they are not as shelf-stable as other components of the poultry ration. Pasture intake by poultry acts as a form of nutritional insurance, as the living forages provide a back-up “bank” of nutrition to prevent any vitamin deficiencies of the feed from affecting the birds.

Vitamins are classified as either water soluble or fat soluble. Fat-soluble vitamins dissolve in body fat and when excess vitamins are consumed, they are able to be stored in the liver and fatty tissues. The fat-soluble vitamins are vitamins A, D, E, and K. Forages are high in all the fat-soluble vitamins except D and are an important natural source of these nutrients for poultry. In confinement production, vitamin D must be added to the poultry ration to prevent the nutritional disease rickets. For pastured poultry production, however, vitamin D deficiency is not a problem because pastured poultry are exposed to ample amounts of sunshine and readily synthesize vitamin D in their skin. With access to plenty of forage and sunlight, poultry on pasture should not have problems with fat-soluble vitamin deficiencies.

Water-soluble vitamins are not able to be stored in the body and need to be consumed regularly. The water-soluble vitamins include several important vitamins grouped together and collectively called the vitamin B complex, as well as vitamin C. Poultry can synthesize vitamin C in their own bodies, and generally don’t need to supplement with dietary intake. The B vitamins consist of vitamins like riboflavin, folic acid, and B6, which are found in ample amounts in pasture vegetation. Vitamins such as niacin, thiamine, and B12 are found in animals (think insects) that poultry eagerly hunt on pasture. Some of the water-soluble vitamins are also produced by bacteria in a healthy poultry gut. Forage consumption plays a significant role in poultry gut health, as will be discussed in the “Fiber” section on page 5.

Poultry feed can often be deficient in vitamins A, D, riboflavin, and B12 due to the perishable nature of these vitamin sources in the feed. As mentioned above, pasturing poultry and giving them access to high-quality forages will help in balancing out any deficiencies. Forages are rich in vitamin A and riboflavin; when exposed to sunshine, a bird’s body manufactures all the vitamin D the bird needs; and vitamin B12 can be supplemented by grasshoppers, crickets, worms, and other invertebrates (and the occasional vertebrate) that are commonplace in healthy pastures.

Minerals

Minerals are inorganic compounds, typically found as salts, that are critical for bone and eggshell formation in poultry, as well as important in many biochemical processes like hormone production and fluid balance in the bird’s body. Many of the minerals needed by poultry can be supplemented by forages.

By far, the most common mineral deficiency is calcium, especially for laying hens. Calcium plays a critical role in poultry health, comprising approximately 70% of the mineral content in a bird. Calcium works hand-in-hand with phosphorous inside of the bird to build strong bones and eggshells. The calcium content of grains is very low, and typically sources like oyster shells, limestone, or calcium salts are added to feed. Forages can provide supplemental minerals, and the calcium found in plants like alfalfa is highly bioavailable. A bird’s digestive system is able to utilize calcium from forages as efficiently as calcium from more common sources like limestone or oyster shell (Blair, 2008). Although pasture can supply around 25% (Horsted, 2006) of the calcium required by layers, it cannot serve as the long-term sole source of calcium. Good pasture with access to supplemental limestone or oyster shell, however, will provide all the calcium the flock needs.

Proteins

Proteins are used by animals to build muscles, organs, and all other tissues. Crude protein is a basic measure of what percentage of a particular feed item is protein. Proteins are comprised of amino acids, of which there are over a dozen types. An easy way to understand protein nutrition is to imagine crude protein as a completed wall made up of individual amino-acid bricks. Each type of amino acid is like a different type of brick, and each animal requires a completed wall (crude protein) with a certain pattern of amino acid bricks (i.e., particular types and numbers of amino acids). When looking at the crude protein of a food, it is important to understand that not all proteins are the same, and that different animals have different levels of amino acid requirements.

Of particular importance in raising poultry, there is one amino acid that can often be limiting: methionine. In grains, methionine is found only in relatively low levels, and the best natural source for methionine is animal proteins – typically fish (fed as a meal), or insects and other animals found while ranging. In the modern poultry industry (including organic), most methionine is supplied in poultry diets by synthetically produced protein powders (the only way that so-called vegetarian poultry diets are possible).

Chickens and turkeys especially crave methionine. One sign of methionine deficiency is an increase in feather pecking or even cannibalism in the flock. One of the major advantages of allowing poultry to forage on pasture is that it allows the birds to hunt and eat insects and other invertebrates that they find while ranging, thus satisfying the bird’s craving for animal protein. Indeed, research has demonstrated that even commercial Cornish Cross broilers are able to make up for some methionine deficiencies by consuming vegetation and insects on pasture (Mortiz et al., 2005; Horsted, 2006).

For decades, poultry farmers have noted that hens given access to pastures full of alfalfa and clover need less protein than hens raised in confinement. Experience has shown that hens purposefully fed protein-deficient diets increased their consumption of pasture forages compared to flocks fed a ration with adequate protein levels (Horsted, 2006). The same behavior was exhibited by broilers fed a protein-deficient diet (Eriksson, 2010). Horsted (2006) reported a 50% increase in forage consumption in hens fed a restricted diet of wheat and oyster shell compared to hens with access to a balanced layer ration. Similarly, poultry scientists have found that consumption of forages is inversely tied to protein levels – i.e., a higher protein content (methionine) in the feed ration can result in a lower amount of plant matter consumed on pasture (Heuser, 1955; Mortiz et al., 2005). A study in 2007 demonstrated that poultry are able to utilize the majority of the amino acids that they consume in forages, finding that the amount of methionine and lysine digested was 88% and 79% of the respective amount consumed (Buchanan et al., 2007;). Rivera-Ferre et al. found that broilers on pasture were able to meet around 7% of their protein needs from foraging (2007). For more information about methionine in poultry, consult the ATTRA publication Organic Poultry Production: Providing Adequate Methionine.

Among plants, the legume family is the king of protein production. Legumes are unique in the plant world because they house a group of bacteria called Rhizobia in their roots that are able to pull atmospheric nitrogen (which composes roughly 70% of the air we breathe) and are able to convert it as a nitrogen fertilizer source for the legumes. In return, the Rhizobia are able to get shelter, water, and sugars from the cells in the legumes’ roots. The abundant nitrogen production of legumes leads to elevated levels of valuable nitrogen-rich protein in these plants. Legumes important in poultry production are soybeans and various field peas, as well as pasture forages like alfalfa, lespedeza, clovers, and vetches.

Energy

As mentioned previously, forages are poor sources of energy, but they still contribute some calories to fuel the bird’s need for energy. Buchanan et al. (2007) reported that a chicken gains anywhere from 129 to 246 calories for each pound of forages consumed (or 285 to 542 kcal/kg) and Rivera-Ferre et al. reported that broilers raised on pasture got only 3% of their energy need from forages (2007). Yellow dent corn, the main supplier of energy in poultry rations, by comparison, supplies around 1,632 calories per pound (3,596 kcal/kg). While grains are obviously one of the most important sources of energy in poultry rations (along with oils), even the small amounts of energy supplied by forages are important when feed prices soar. Forages can play a small but key role in reducing the feed bill in a pastured poultry operation.

Fiber

Although fiber is often overlooked, research is increasingly showing that it is an important component of poultry diets. Fiber generally falls into two categories: digestible and indigestible. Both types have roles in maintaining a healthy poultry digestive system.

Digestible fiber is fiber that gets broken down by the bacteria in the bird’s digestive tract. Digestible fiber is an excellent food source for beneficial bacteria like Lactobacillus sp and Bifidobacteria. Additionally, lactic acid and other beneficial compounds are produced as these beneficial bacteria ferment digestible fiber, stimulating gut health. The competitive presence of populations of these beneficial bacteria, as well as the lower pH resulting from the fermentation of the fiber, creates a difficult environment for the establishment of Salmonella and other pathogenic populations (Nurmi and Ratala, 1973; Esmail, 2012).

Indigestible fiber does not get broken down as it moves through the bird’s gut. This type of fiber does, however, slow things down considerably by bulking up the food and helping the gut “grip” the feed. Indigestible fiber typically is very water-absorbent, and allows water more time to be absorbed by the digestive system, especially in the large intestines.

When evaluating the nutrition of a particular feed item, it is helpful to understand a few terms that involve fiber:

Crude Fiber (CF) – CF expresses the percentage of the feed item that is made of fiber, both digestible and indigestible.

Total Digestible Nutrients (TDN) – this term refers to the sum of all the digestible parts of a feed item, including fiber, fats, proteins, and carbohydrates. Expressed as a percentage, it represents what can be digested by the animal; the remainder is indigestible.

Acid Detergent Fiber (ADF) – refers to the indigestible plant parts, including cellulose and lignin, that make up the outer walls of individual plant cells and, on a larger scale, the walls of leaves and stalks.

When building poultry rations, the greatest concern associated with fiber is having too much in the diet, which can cause a drastic drop in poultry performance and health. It is advisable to stick with a ration recipe formulated by a poultry nutritionist, especially in confinement situations. Poultry have the ability to at least partially regulate fiber intake, as birds in confinement have been observed supplementing their fiber intake by eating wood shavings from the litter when fed a fiber-limited diet. With access to pasture, poultry are able to round out any fiber deficiencies on their own, especially if given a wide variety of forages to choose from. Grasses are more fibrous than legumes, and grasses often have two or three times the fiber concentration of legumes in similar growth stages (Buxton and Redfearn, 1997)