An animal feeding operation is defined by the United
States Environmental Protection Agency as a lot or facility
where:
Note that this is different from a EPA's definition of a confined animal feeding operation which is an animal feeding operation larger than a given size.
Asphyxiation is the deficiency of oxygen in the air, making it difficult or impossible to breathe.
Ensiling is a process by which fodder or feed is stored in a silo in order to be converted into ensilage, a more succulent feed for livestock. The silo air access to the structure to encourage fermentation. The lack of oxygen and acid conditions prevent spoilage and preserve the value of the stored feed for several months.
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Farrowing is the stage in swine operations during which the pigs are born, and kept until they are weaned from the sow.
Finishing stage in swine operations is the growth stage leading up to market. Pigs remain here until they reach market weight, typically 240 to 275 pounds.
Gastroenteritis is a disorder of the digestive tract that stems from the presence of bacteria consumed by the animal.
The growing stage in swine operations occurs after the piglets leave the nursery and before they enter the finishing unit.. Pigs are larger and better able to take care of themselves than in the nursery, so larger pens and a less controlled environment is often used. They are typically kept here until they reach 120 to 140 pounds. Many of today's swine operations have combined the growing and finishing stages into a single building with the pigs enterining from the nursery and leaving at market. Yet other farms have modified these buildings so that weaned pigs from farrowing enter this "wean-to-finish" unit and stay until market, literally from 3 weeks until about 25 weeks of age.
Deep narrow gutters were popular before slotted floors came into common use, in the early to mid 1960's. Few of these units remain today. Deep narrow gutters are basically self cleaning as pigs work the manure down a sloped floor with their foot traffic to the gutter. The gutter is fitted with a watertight plug that can be pulled as often as once a day to drain manure to an outside storage facility.
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In gravity drain gutters, liquid manure is allowed to build up in the gutters for a period of days or weeks. Periodically, a plug is pulled and the manure drains out by gravity to a storage tank or lagoon, or into a sump where it is pumped into storage. After drainage, 3-4 inches of fresh water is sometimes added to in the gutter to absorb ammonia from freshly added manure, and to keep the manure from drying. This system uses less water than flushing systems. In swine units, a modification of this is the "hairpin gutter" where a long 8' wide gutter is divided into two 4' wide units with a divider. Drains are placed on each side of the gutter on the closed end with the sides connected on the other by stopping the divider about 4 feet from the other end. One of the drains is opened on each side of the gutter every 3 days or so to send the manure to first one side of the hairpin (or horseshoe) and to the other the next time. This back and forth drainage action tends to prevent solids from building up in the gutter. The drains typically connect to an outside storage unit.
There are 2 types of gravity drain gutters:
Y gutter
The Y gutter is an adaptation of the deep narrow gutter and has normally used only for swine, whose purpose is to provide a cleaning action of the narrow gutter with some slotted flooring above the gutter to provide cleaner floors. Aconsistent problem has been poor cleaning of manure that falls on the sloping sidewalls and the resultant fly breeding and odor problems.
Rectangular gutter
The rectangular gutter is easier to construct than Y gutters. The gutter bottom is flat from end to end. In gutters less than about 40 feet, a drain is sometimes placed near the center of the length or at one end. In longer gutters several drains may be needed. In rectangular gutters wider than about 6 feet, a divider wall is sometimes placed down the center of the length extending to within 3-4 feet of the end furthest from the drain, forming a hairpin or horseshoe shape. Drains are then placed in both ends of the horseshoe and the plugs are pulled in alternating fashion every week or so.
Underslat gutters are used in beef buildings and swine farrowing, nursery, and gestation facilities where residue and disease transmission is a concern. The width of the gutter is determined by the amount of slotted floor necessary to keep the animals clean. Manure is either stored in the pit for several months or gutter or removed frequently by flushing, scraping or draining.
Wide open gutters are primarily used for 10 to 12 feet wide dairy free stall alleys. If the alley is flushed with water, the gutter usually has a slope of 3-5% and a flood depth of 4-6 inches.
Although similar to the deep-pit used for liquid manure storage beneath slotted floors, the high-rise is built entirely above ground. It is constructed with a concrete floor and masonry block or concrete side walls, with pens or cages built on slotted floors 8 or more feet above the pit floor. Foundation drains and external grading help to keep the manure dry.
The interface layer is a 3-4 inch layer of compacted manure next to the soil surface. This layer acts as a seal or anaerobic zone for denitrification, reducing liquid percolation down into the soil.
Liquid manure is usually less than 8.0% solids. Wash water, runoff, precipitation, and so forth are added to dilute the manure and lower the solids content, if needed, for proper agitation and removal. If placed in an anaerobic treatment lagoon, a significant amount of dilution water, depending on the local evaporation rate, in order to control odors and ensure adequate treatment.
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Methemoglobinemia is an illness caused by high levels of nitrate in drinking water. Infants and small animals are particularly susceptible to methemoglobinemia. Current safe drinking water standards call for nitrate levels below 10ppm nitrate-N.
The nursery building in swine operations is used for the piglets after they are weaned. Pigs are kept in small groups in this heated, well-insulated enclosure until they reach 8 to 12 weeks of age. A wire or other very porous floor is used to conditions of high sanitation. The nursery phase is sometimes broken up into two growth stages (or age ranges), called, respectively, a "hot" and "cold" nursery, reflecting the room temperatures used.
An open lot is an outdoor fenced animal area used for feeding, handling, and resting and may be paved or unpaved. Open lots often require two manure handling methods. Solid or semi-solid manure from bedded buildings or lots is removed manually with mechanical scrapers and front-end loaders for storage and land application. Rainfall runoff that has come in contact with manure must also be stored and applied to cropland.
The deep pit solid manure system, or high-rise building, has a concrete floor and masonry or concrete side walls and is typically constructed 2-6 feet below the ground. Pens or cages are then built on slotted flooring 8 feet or more above the pit floor. Because the pit is often built below ground level, care must be taken to insure that surface and ground water are not contaminated. Foundation drains and external grading to direct surface water away help to keep manure dry, so that natural composting might occur. High rates of air movement from mechanical fans located in the pit help to keep the manure relatively dry. A benefit of the deep pit system is that manure can be stored for several months before removal. This type of unit is typically used for sheep and poultry because that manure tends to be nearly solid as it is produced. It has also been used for swine manure where bedding such as chopped corn stalks is placed over the pit floor before animals are placed in the barn.
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The shallow- pit, usually covered with a slotted floor is a very common way to handle manure from poultry production. The 4-8 inches deep concrete pit is located 3-6 feet below the cages. The manure is mechanically scraped or flushed with water to a storage area, or directly loaded into a spreader for field application.
Pullets are young female poultry.
Ruminant animals are four-stomached animals with even-toed hooves. Farm animals such as cattle, sheep, and goats are ruminants; swine and poultry are not.
There are several systems of screening and filtration that may be used to separate manure solids from liquids. They include:
Stationary Screen
Stationary Screen: solids move across the face of an inclined screen to a storage unit while liquids pass through and drain to a liquid storage.
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Vibrating Screen
Vibrating Screen: the screen vibrates rapidly to assist with the movement of solids across the screen, allowing the liquid to fall through to one storage, with the separated solids sent to another storage..
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Rotating Screen
Rotating Screen: solids pass between a series of cylindrical screens and press rollers to remove the liquids and into a storage unit while the liquids drain away through the screens to a liquid storage unit.
Porous Belt
Porous Belt: liquids are pressed through a porous belt by rollers while the solids are carried along on top of the belt.
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In regions where evaporation exceeds rainfall, evaporation ponds may be used to dry livestock manure. The pond should be large enough to hold all the manure during the wet season, plus runoff from the any storms expected over the storage time.
Dehydrators usually have a large rotating drum with a sizable electrical power demand. Fresh manure usually does not work well in the dryer. Manureentering the dryer should have a moisture content between 40% and 60%. Dehydrators can remove nearly all moisture from manure, but they are require too much energy to be economical for a livestock operation:
Semi-solid manure has little bedding and usually no extra water added. In most cases, little drying occurs before handling. During wet weather the manure scraped from open lots can also be semi-solid in nature.
Settling basins should be placed between the lot and a holding pond or infiltration area to remove large manure solids that float or settle from the runoff. Paved shallow basins or channels provide for easy cleaning after runoff occurs. Settling basins in use on farms are of two types: one that is rectangular and solids are periodically pumped from the tank and a unit that is porous at one end so that liquid slowly drains from the tank. The latter is "dewatered" by gravity and requires a 10-12% sloping ramp to allow solids removal with front-end loaders.
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A settling channel is a shallow, flat-bottomed waterway with a slight slope to maintain low velocities of runoff so that solids settle and dry naturally. The channel has a bottom width of 10 feet or more and is usually tractor scraped annually or as needed to remove solids. Settling channels should only be cleaned when solids are dry enough to handle with a scraper and loader.
Settling tanks work well to control feedlot runoff. They are usually made of concrete and are designed to provide adequate settling time for some design storm, depending on state regulations. Solids are removed from this type of unit by thorough agitation and pumping followed by land agitation. Additional dilution is sometimes needed to remove all solids..
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Aluminum slotted flooring provides easy cleaning and the reduction of animal foot and knee abrasions compared to some other floors. It can be noisy as animals walk on it if not well-supported. Deterioration can be a problem, so steel waterers, feeders, and fencing must be insulated from aluminum to prevent electrolytic corrosion.
Concrete slotted flooring is the most durable of all the slotted flooring materials and is used for larger animals such as mature swine and cattle. It can be pre-cast or cast in place, and requires load-bearing reinforcing steel in the slat to provide strength over the span. Providing a smooth edge on the slats helps prevent foot injuries, and improves cleaning.
Plastic slotted floors work very well for young animals and are often giberglass reinforced and fabricated with a textured surface.
Steel is used to make slotted floors
for small animals such as young pigs, calves, and sheep. Epoxy paint or a porcelain
or plastic coating helps to resist corrosion.
Galvanized steel is a type of steel that is treated with a zinc coating
to protect against water and its corrosive forces.
Stainless steel lasts longer than galvanized steel and is best suited for swine farrowing and nursery buildings. It is also used to make grates used to cover gutters behind dairy cow stalls.
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Slotted floors made of wood are limited to smaller animals such as veal calves, and sheep. Construction has a low initial cost but also a short life span of 2-4 years. Oak is the best wood to use for the slats although hickory or hard maple are also possibilities. Wood tends to be porous and is more difficult to sanitize between animal groups than steel, plastic or concrete.
Solid manure is a combination of urine, bedding, and feces with little or no extra water added. It is usually found in loafing barns, calving pens, and open lots with good drainage.
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