Managed intensive grazing
Encyclopedia
Management Intensive Rotational Grazing (MIRG) is a system of grazing
in which ruminant
and non-ruminant herds are regularly and systematically moved to fresh pasture with the intent to maximize the quality and quantity of forage
growth. MIRG can be used with cattle, sheep, goats, pigs, chickens, ducks and other animals. The herds graze one portion of pasture, or a paddock, while allowing the others to recover. The length of time a paddock is grazed will depend on the size of the herd and the size of the paddock
. Resting grazed lands allows the vegetation to renew energy reserves, rebuild shoot systems, and deepen root systems, with the end result being long-term maximum biomass
production. MIRG is especially effective because grazers do better on the more tender younger plant stems. MIRG also leave parasites behind to die off minimizing or eliminating the need for de-wormers. Pasture systems alone can allow grazers to meet their energy requirements, and with the increased productivity of MIRG systems, the grazers obtain the majority of their nutritional needs without the supplemental feed sources that are required in continuous grazing systems.
or poultry
that if left untreated can lead to animal death. This problem occurs when foam producing compounds in plants are digested by cows, causing foam to form in the rumen of the animal and ultimately prohibiting animals from expelling gas. The risk of bloat can be mitigated by seeding non-bloating legumes with the grasses. Animals are especially susceptible to bloat if they are moved to new pasture sources when they are particularly hungry. It is therefore important to ensure that the herd is eating enough at the end of a rotation when forage will be more scarce, limiting the potential for animals to gorge themselves when turned onto new paddocks.
Several problems are related to shade in pasture
areas. Although shade provides relief from heat and reduces the risk of heat stress, animals tend to congregate in these areas which leads to nutrient loading, uneven grazing, and potential soil erosion. Taller shade trees move the shade area around as the day progresses minimizing this problem.
, which limits the potential for injuries and abrasion, and reduces the potential of exposure to high levels of harmful disease causing microorganism
s and insects.
A key step in managing weeds in any pasture system is identification. Once the undesired species in a pasture system are identified an integrated approach of management can be implemented to control weed populations. It is important to recognize that no single approach to weed management will result in weed free pastures; therefore, various cultural, mechanical, and chemical control methods can be combined in an integrated weed management plan. Cultural controls include avoiding spreading manure contaminated with weed seeds, cleaning equipment after working in weed infested areas, and managing weed problems in fencerows and other areas near pastures. Mechanical controls such as repeated mowing, clipping, and hand weeding can also be used to effectively manage weed infestations by weakening the plant. These methods should be implemented when weed flower buds are closed or just starting to open to prevent seed production. Although these methods for managing weeds greatly reduces reliance on herbicides, weeds problems may still persist in managed grazing systems and the use of herbicides may become necessary. Use of herbicides may restrict use of a pasture for some length of time, depending on the type and amount of the chemical used. Frequently weeds in pasture systems are patchy and therefore spot treatment of herbicides may be used as a least cost methods of chemical control.
Although grazers remove nutrient sources from the pasture system when they feed on forage sources, the majority of the nutrients consumed by the herd are returned to the pasture system through manure
. At a relatively high stocking rate, or high ration of animals per hectare
, manure will be evenly distributed across the pasture system. The nutrient content in these manure sources should be adequate to meet plant requirements, making commercial fertilization unnecessary. Management intensive rotational grazing systems are often associated with increased soil fertility which arises because manure is a rich source of organic matter
that increases the health of soil. In addition, these pasture system are less susceptible to erosion
because the land base has continuous ground cover throughout the year.
High levels of fertilizers entering waterways are a pertinent environmental concern associated with agricultural systems. However, management intensive rotational grazing systems effectively reduce the amount of nutrients that move off-farm and have the potential to cause environmental degradation. These systems are fertilized with on-farm sources, and are less prone to leaching as compared to commercial fertilizers. Additionally, the system is less prone to excess nutrient fertilization, so the majority of nutrients put into the system by manure sources are utilized for plant growth. Permanent pasture systems also have deeper, well established forage root systems which are more efficient at taking up nutrients from within the soil profile.
The main costs associated with transitioning to management intensive rotational grazing are purchasing fencing, fencers, and water supply materials. If a pasture was continuously grazed in the past, likely capital has already been invested in fencing and a fencer system. Cost savings to graziers can also be recognized when one considers that many of the costs associated with livestock operations are transmitted to the grazers. For example, the grazers actively harvest their own sources of food for the portion of the year where grazing is possible. This translates into lower costs for feed production and harvesting, which are fuel intensive endeavors. MIRG systems rely on the grazers to produce fertilizer sources via their excretion. There is also no need for collection, storage, transportation, and application of manure, which are also all fuel intensive. Additionally, external fertilizer use contributes to other costs such as labor, purchasing costs.
It can also be demonstrated that management intensive rotational grazing system also result in time savings because the majority of work which might otherwise require human labor is transmitted to the herd.
Grazing
Grazing generally describes a type of feeding, in which a herbivore feeds on plants , and also on other multicellular autotrophs...
in which ruminant
Ruminant
A ruminant is a mammal of the order Artiodactyla that digests plant-based food by initially softening it within the animal's first compartment of the stomach, principally through bacterial actions, then regurgitating the semi-digested mass, now known as cud, and chewing it again...
and non-ruminant herds are regularly and systematically moved to fresh pasture with the intent to maximize the quality and quantity of forage
Forage
Forage is plant material eaten by grazing livestock.Historically the term forage has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used more loosely to include similar plants cut for fodder and carried to the animals, especially...
growth. MIRG can be used with cattle, sheep, goats, pigs, chickens, ducks and other animals. The herds graze one portion of pasture, or a paddock, while allowing the others to recover. The length of time a paddock is grazed will depend on the size of the herd and the size of the paddock
Field (agriculture)
In agriculture, the word field refers generally to an area of land enclosed or otherwise and used for agricultural purposes such as:* Cultivating crops* Usage as a paddock or, generally, an enclosure of livestock...
. Resting grazed lands allows the vegetation to renew energy reserves, rebuild shoot systems, and deepen root systems, with the end result being long-term maximum biomass
Biomass
Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....
production. MIRG is especially effective because grazers do better on the more tender younger plant stems. MIRG also leave parasites behind to die off minimizing or eliminating the need for de-wormers. Pasture systems alone can allow grazers to meet their energy requirements, and with the increased productivity of MIRG systems, the grazers obtain the majority of their nutritional needs without the supplemental feed sources that are required in continuous grazing systems.
Animal health risks
Bloat is a common problem in grazing systems for ruminants although not for pigsPIGS
PIGS is a four letter acronym that can stand for:* PIGS , Phosphatidylinositol glycan anchor biosynthesis, class S, a human gene* PIGS , the economies of Portugal, Italy , Greece and Spain...
or poultry
Poultry
Poultry are domesticated birds kept by humans for the purpose of producing eggs, meat, and/or feathers. These most typically are members of the superorder Galloanserae , especially the order Galliformes and the family Anatidae , commonly known as "waterfowl"...
that if left untreated can lead to animal death. This problem occurs when foam producing compounds in plants are digested by cows, causing foam to form in the rumen of the animal and ultimately prohibiting animals from expelling gas. The risk of bloat can be mitigated by seeding non-bloating legumes with the grasses. Animals are especially susceptible to bloat if they are moved to new pasture sources when they are particularly hungry. It is therefore important to ensure that the herd is eating enough at the end of a rotation when forage will be more scarce, limiting the potential for animals to gorge themselves when turned onto new paddocks.
Several problems are related to shade in pasture
Pasture
Pasture is land used for grazing. Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, cattle, sheep or swine. The vegetation of tended pasture, forage, consists mainly of grasses, with an interspersion of legumes and other forbs...
areas. Although shade provides relief from heat and reduces the risk of heat stress, animals tend to congregate in these areas which leads to nutrient loading, uneven grazing, and potential soil erosion. Taller shade trees move the shade area around as the day progresses minimizing this problem.
Animal health benefits and animal welfare
Herd health benefits arise from animals having access to both space and fresh air. Freedom of movement within a paddock results in increased physical fitnessPhysical fitness
Physical fitness comprises two related concepts: general fitness , and specific fitness...
, which limits the potential for injuries and abrasion, and reduces the potential of exposure to high levels of harmful disease causing microorganism
Microorganism
A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...
s and insects.
Weed control
In general, well managed rotational grazing system have rather low pasture weed establishment because the majority of niches are already filled with established forage species, making it hard for competing weeds to emerge and become established. The use of multiple species in the co-grazing helps to minimize weeds. The technique of rotational grazing was developed by Larry Robertson of Vanleer, TN. He also is famous for the development that led to huge yields in tobacco production (the famous cultipacking technique). He is known as the savior to British implant folk on Bell Hollow Rd. in Cumberland Furnace, TN. Established forage plants in rotational grazing pasture systems are healthy and unstressed due to the "rest" period, enhancing the competitive advantage of the forage. Additionally, in comparison to cash grain crop production, plants which would be considered weeds are not problematic in row crops. Many of these plants are actually nutritious to grazers and control of these plants is therefore not necessary in management intensive rotational systems. However, certain species such as thistles and various other weeds, are indigestible and possibly poisonous to grazers. These plant species will not be grazed by the herd and can be recognized for their prevalence in pasture systems.A key step in managing weeds in any pasture system is identification. Once the undesired species in a pasture system are identified an integrated approach of management can be implemented to control weed populations. It is important to recognize that no single approach to weed management will result in weed free pastures; therefore, various cultural, mechanical, and chemical control methods can be combined in an integrated weed management plan. Cultural controls include avoiding spreading manure contaminated with weed seeds, cleaning equipment after working in weed infested areas, and managing weed problems in fencerows and other areas near pastures. Mechanical controls such as repeated mowing, clipping, and hand weeding can also be used to effectively manage weed infestations by weakening the plant. These methods should be implemented when weed flower buds are closed or just starting to open to prevent seed production. Although these methods for managing weeds greatly reduces reliance on herbicides, weeds problems may still persist in managed grazing systems and the use of herbicides may become necessary. Use of herbicides may restrict use of a pasture for some length of time, depending on the type and amount of the chemical used. Frequently weeds in pasture systems are patchy and therefore spot treatment of herbicides may be used as a least cost methods of chemical control.
Nutrient availability and soil fertility
If pasture systems are seeded with more than 40% legumes, commercial nitrogen fertilization is unnecessary for adequate plant growth. Legumes are able to fix atmospheric nitrogen, thus providing nitrogen for themselves and surrounding plants.Although grazers remove nutrient sources from the pasture system when they feed on forage sources, the majority of the nutrients consumed by the herd are returned to the pasture system through manure
Manure
Manure is organic matter used as organic fertilizer in agriculture. Manures contribute to the fertility of the soil by adding organic matter and nutrients, such as nitrogen, that are trapped by bacteria in the soil...
. At a relatively high stocking rate, or high ration of animals per hectare
Hectare
The hectare is a metric unit of area defined as 10,000 square metres , and primarily used in the measurement of land. In 1795, when the metric system was introduced, the are was defined as being 100 square metres and the hectare was thus 100 ares or 1/100 km2...
, manure will be evenly distributed across the pasture system. The nutrient content in these manure sources should be adequate to meet plant requirements, making commercial fertilization unnecessary. Management intensive rotational grazing systems are often associated with increased soil fertility which arises because manure is a rich source of organic matter
Organic matter
Organic matter is matter that has come from a once-living organism; is capable of decay, or the product of decay; or is composed of organic compounds...
that increases the health of soil. In addition, these pasture system are less susceptible to erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
because the land base has continuous ground cover throughout the year.
High levels of fertilizers entering waterways are a pertinent environmental concern associated with agricultural systems. However, management intensive rotational grazing systems effectively reduce the amount of nutrients that move off-farm and have the potential to cause environmental degradation. These systems are fertilized with on-farm sources, and are less prone to leaching as compared to commercial fertilizers. Additionally, the system is less prone to excess nutrient fertilization, so the majority of nutrients put into the system by manure sources are utilized for plant growth. Permanent pasture systems also have deeper, well established forage root systems which are more efficient at taking up nutrients from within the soil profile.
Socio-cultural-economic considerations
Although milk yields are often lower in MIRG systems, net farm income per cow is often greater as compared to confinement operations. This is due to the additional costs associated with herd health and purchased feeds are greatly reduced in management intensive rotational grazing systems. Additionally, a transition to management intensive rotational grazing is associated with low start-up and maintenance costs.The main costs associated with transitioning to management intensive rotational grazing are purchasing fencing, fencers, and water supply materials. If a pasture was continuously grazed in the past, likely capital has already been invested in fencing and a fencer system. Cost savings to graziers can also be recognized when one considers that many of the costs associated with livestock operations are transmitted to the grazers. For example, the grazers actively harvest their own sources of food for the portion of the year where grazing is possible. This translates into lower costs for feed production and harvesting, which are fuel intensive endeavors. MIRG systems rely on the grazers to produce fertilizer sources via their excretion. There is also no need for collection, storage, transportation, and application of manure, which are also all fuel intensive. Additionally, external fertilizer use contributes to other costs such as labor, purchasing costs.
It can also be demonstrated that management intensive rotational grazing system also result in time savings because the majority of work which might otherwise require human labor is transmitted to the herd.
Environmental considerations
Pastures undergoing MIRG are less susceptible to soil erosion and associated with higher soil fertility than continuously grazed pastures. As a result, the system requires fewer commercial inputs, which have been associated with negative environmental impacts. In addition, because these systems tend to be more resilient and stable they are more capable of responding to changing environmental conditions and perturbations while not compromising productivity.See also
- YardingYardingIn poultry keeping, yarding is the practice of providing the poultry with a fenced yard in addition to a poultry house. Movable yarding is a form of managed intensive grazing.Yarding is often confused with free range...
- Pastured poultryPastured poultryPastured poultry is a sustainable agriculture technique that calls for the raising of laying chickens, meat chickens , and/or turkeys on pasture, as opposed to indoor confinement...
- Free rangeFree rangethumb|250px|Free-range chickens being fed outdoors.Free range is a term which outside of the United States denotes a method of farming husbandry where the animals are allowed to roam freely instead of being contained in any manner. In the United States, USDA regulations apply only to poultry and...
- AgroecologyAgroecologyAgroecology is the application of ecological principles to the production of food, fuel, fiber, and pharmaceuticals. The term encompasses a broad range of approaches, and is considered "a science, a movement, [and] a practice."...
- Organic agriculture
- Electric fenceElectric fenceAn electric fence is a barrier that uses electric shocks to deter animals or people from crossing a boundary. The voltage of the shock may have effects ranging from uncomfortable, to painful or even lethal...
- Soil conservationSoil conservationSoil conservation is a set of management strategies for prevention of soil being eroded from the Earth’s surface or becoming chemically altered by overuse, acidification, salinization or other chemical soil contamination...
- NRCS