Rotational grazing

In agriculture, rotational grazing, as opposed to continuous grazing, describes many systems of pasturing, whereby livestock are moved to portions of the pasture, called paddocks, while the other portions rest. Each paddock must provide all the needs of the livestock, such as food, water and sometimes shade and shelter. The approach often produces lower outputs than more intensive animal farming operations, but requires lower inputs, and therefore sometimes produces higher net farm income per animal.

Approach

In rotational grazing livestock are moved to portions of the pasture, called paddocks, while the other portions rest. The intent is to allow the pasture plants and soil time to recover. Healing native rangeland may require a combination of burning and rotational grazing. Rotational grazing can be used with ruminants such as cattle, sheep or goats; non-ruminants such as pigs can also be used. 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 and local environmental factors. Resting grazed lands allows the vegetation to regrow. Rotational grazing is especially effective because grazers do better on the more tender younger plant stems. These systems may or may not leave parasites behind to die off, minimizing or eliminating the need for de-wormers, depending if the rotational time is smaller or larger than the parasitic life cycle.

Benefits Herd health benefits arise from animals having access to both space and fresh air. Freedom of movement within a paddock results in increased physical fitness, which limits the potential for injuries and abrasion, and sometimes depending on the system reduces the potential of exposure to high levels of harmful disease-causing microorganisms and insects. In a concentrated animal feeding operation it is normal for a large number of animals to continuously occupy a small area. By comparison, with managed grazing, the animals are able to live in a more natural environment. The animals experience less disease and fewer foot ailments, depending on the rotational system being used. Managed rotational grazing is a key component of a regenerative agriculture system, as it functions as a constant feedback loop. Rotational grazing has been said to be more environmentally friendly in certain cases. Many pastures undergoing certain types of rotational grazing are less susceptible to soil erosion. Paddocks might require fewer inputs. These grazing regimes are sometimes said to be more resilient and more capable of responding to changing environmental conditions. Rotational grazing may reduce greenhouse gas emissions such as carbon dioxide, nitrous oxides, and methane. One study looking at finishing stages suggested that adaptive multi-paddock grazing could result in a net carbon sink. However, the study's authors have cautioned that the results are limited in scope as they are only looking at one stage of an experimental system. Other studies have also found some land may sequester just as much or more without any grazing.

Problems A key element of this style of animal husbandry is that either each grazed area must contain all elements needed for the animals (water source, for instance) or the feed or water source must be moved each time the animals are moved. Having fixed feeding or watering stations can defeat the rotational aspect, leading to degradation of the ground around the water supply or feed supply if additional feed is provided to the animals. Special care must be taken to ensure that high use areas do not become areas where mud, parasites or diseases are spread or communicated. 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. Ruminal tympany, also known as bloat, is a common serious problem when ruminants graze on fresh, young pasture, and if left untreated can be fatal. This problem occurs when foam producing compounds in plants are digested by cows, causing foam to form in the rumen of the animal and not allowing animals to properly belch gas. Animals are especially susceptible to bloat if they are moved to new pasture sources when they are particularly hungry and especially on young, fresh and wet legumes. 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 out onto new paddocks. The risk of bloat can be mitigated by careful management of rotations, seeding the non-bloating European legume species Lotus corniculatus in pasturelands, reducing the amount of legumes/increasing grasses, providing sufficient supplemental feeding and extra fodder when turning out on new paddocks, reducing the size of the paddock when livestock is first turned out, and daily rations of the anti-foaming agent poloxalene mixed well into the fodder.

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