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Silage () is a type of
fodder Fodder (), also called provender (), is any agricultural foodstuff used specifically to feed domesticated livestock, such as cattle, rabbits, sheep, horses, chickens and pigs. "Fodder" refers particularly to food given to the animals (includin ...
made from green foliage crops which have been preserved by
fermentation Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food p ...
to the point of acidification. It can be fed to
cattle Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Adult females are referred to as cows and adult ...
,
sheep Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus ''Ovis'', in everyday usage it almost always refers to domesticated ...
and other such
ruminant Ruminants ( suborder Ruminantia) are hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. The ...
s (
cud Cud is a portion of food that returns from a ruminant's stomach to the mouth to be chewed for the second time. More precisely, it is a bolus of semi-degraded food regurgitated from the reticulorumen of a ruminant. Cud is produced during the phy ...
-chewing animals). The fermentation and storage process is called ''ensilage'', ''ensiling'' or ''silaging''. Silage is usually made from
grass crops Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns a ...
, including
maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn ( North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. T ...
,
sorghum ''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family ( Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species is grown for grain, while many oth ...
or other
cereal A cereal is any grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, germ, and bran. Cereal grain crops are grown in greater quantities and provide more food e ...
s, using the entire green plant (not just the grain). Silage can be made from many field crops, and special terms may be used depending on type: ''oatlage'' for oats, ''haylage'' for
alfalfa Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, and silage, as ...
(''haylage'' may also refer to high dry matter silage made from
hay Hay is grass, legumes, or other herbaceous plants that have been cut and dried to be stored for use as animal fodder, either for large grazing animals raised as livestock, such as cattle, horses, goats, and sheep, or for smaller domesticated ...
). Silage can be made using several methods, largely dependent on available technology, local tradition or prevailing climate.


Production

The crops most often used for ensilage are the ordinary grasses,
clover Clover or trefoil are common names for plants of the genus ''Trifolium'' (from Latin ''tres'' 'three' + ''folium'' 'leaf'), consisting of about 300 species of flowering plants in the legume or pea family Fabaceae originating in Europe. The genus ...
s,
alfalfa Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, and silage, as ...
,
vetch ''Vicia'' is a genus of over 240 species of flowering plants that are part of the legume family (Fabaceae), and which are commonly known as vetches. Member species are native to Europe, North America, South America, Asia and Africa. Some other ...
es, oats, rye and
maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn ( North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. T ...
. Many crops have ensilaging potential, including
potato The potato is a starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial in the nightshade family Solanaceae. Wild potato species can be found from the southern United ...
es and various
weed A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...
s, notably spurrey such as '' Spergula arvensis''. Silage must be made from plant material with a suitable moisture content: about 50% to 60% depending on the means of storage, the degree of compression, and the amount of water that will be lost in storage, but not exceeding 75%. Weather during harvest need not be as fair and dry as when harvesting for drying. For corn, harvest begins when the whole-plant moisture is at a suitable level, ideally a few days before it is ripe. For pasture-type crops, the grass is mown and allowed to wilt for a day or so until the moisture content drops to a suitable level. Ideally the crop is mowed when in full
flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanism ...
, and deposited in the silo on the day of its cutting. After harvesting, crops are shredded to pieces about long. The material is spread in uniform layers over the floor of the silo, and closely packed. When the silo is filled or the stack built, a layer of
straw Straw is an agricultural byproduct consisting of the dry stalks of cereal plants after the grain and chaff have been removed. It makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has a number ...
or some other dry porous substance may be spread over the surface. In the silo, the pressure of the material, when
chaff Chaff (; ) is the dry, scaly protective casing of the seeds of cereal grains or similar fine, dry, scaly plant material (such as scaly parts of flowers or finely chopped straw). Chaff is indigestible by humans, but livestock can eat it. In agri ...
ed, excludes air from all but the top layer; in the case of the stack, extra
pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and ...
is applied by weights to prevent excessive heating.


Equipment

Forage harvester A forage harvesteralso known as a silage harvester, forager or chopperis a farm implement that harvests forage plants to make silage. Silage is grass, corn or hay, which has been chopped into small pieces, and compacted together in a storage sil ...
s collect and chop the plant material, and deposit it in trucks or wagons. These forage harvesters can be either
tractor A tractor is an engineering vehicle specifically designed to deliver a high tractive effort (or torque) at slow speeds, for the purposes of hauling a Trailer (vehicle), trailer or machinery such as that used in agriculture, mining or construc ...
-drawn or self-propelled. Harvesters blow the chaff into the wagon through a chute at the rear or side of the machine. Chaff may also be emptied into a bagger, which puts the silage into a large plastic bag that is laid out on the ground. In North America, Australia, northwestern Europe, and New Zealand it is common for silage to be placed in large heaps on the ground, rolled by tractor to push out the air, then covered with plastic sheets that are held down by used tires or tire ring walls. In New Zealand and Northern Europe, 'clamps' made of concrete or old wooden railway ties (sleepers) and built into the side of a bank are sometimes used. The chopped grass can then be dumped in at the top, to be drawn from the bottom in winter. This requires considerable effort to compress the stack in the silo to cure it properly. Again, the pit is covered with plastic sheet and weighed down with tires. In an alternative method, the cut vegetation is formed into bales using a
baler A baler or hay baler is a piece of farm machinery used to compress a cut and raked crop (such as hay, cotton, flax straw, salt marsh hay, or silage) into compact bales that are easy to handle, transport, and store. Often, bales are configure ...
, making ''balage'' (North America) or ''silage bales'' (UK, Australia, New Zealand). The grass or other forage is cut and partly dried until it contains 30–40% moisture (much drier than bulk silage, but too damp to be stored as dry hay). It is then made into large bales which are wrapped tightly in plastic to exclude air. The plastic may wrap the whole of each cylindrical or cuboid bale, or be wrapped around only the curved sides of a cylindrical bale, leaving the ends uncovered. In this case, the bales are placed tightly end to end on the ground, making a long continuous "sausage" of silage, often at the side of a field. The wrapping may be performed by a bale wrapper, while the baled silage is handled using a bale handler or a
front-loader A loader is a Heavy equipment (construction), heavy equipment machine used in construction to move or load materials such as soil, Rock (geology), rock, sand, demolition debris, etc. into or onto another type of machinery (such as a dump truck ...
, either impaling the bale on a flap, or by using a special grab. The flaps do not hole the bales. In the UK, baled silage is most often made in round bales about , individually wrapped with four to six layers of "bale wrap plastic" (black, white or green 25-micrometre stretch film). The percentage of dry matter can vary from about 20% dry matter upwards. The continuous "sausage" referred to above is made with a special machine which wraps the bales as they are pushed through a rotating hoop which applies the bale wrap to the outside of the bales (round or square) in a continuous wrap. The machine places the bales on the ground after wrapping by moving forward slowly during the wrapping process.


Haylage

''Haylage'' sometimes refers to high dry matter silage of around 40% to 60%, typically made from
hay Hay is grass, legumes, or other herbaceous plants that have been cut and dried to be stored for use as animal fodder, either for large grazing animals raised as livestock, such as cattle, horses, goats, and sheep, or for smaller domesticated ...
. Horse haylage is usually 60% to 70% dry matter, made in small bales or larger bales. Handling of wrapped bales is most often with some type of gripper that squeezes the plastic-covered bale between two metal parts to avoid puncturing the plastic. Simple fixed versions are available for round bales which are made of two shaped pipes or tubes spaced apart to slide under the sides of the bale, but when lifted will not let it slip through. Often used on the tractor rear three-point linkage, they incorporate a trip tipping mechanism which can flip the bales over on to the flat side or end for storage on the thickest plastic layers.


Fermentation

Silage undergoes anaerobic fermentation, which starts about 48 hours after the silo is filled, and converts sugars to acids. Fermentation is essentially complete after about two weeks. Before anaerobic fermentation starts, there is an aerobic phase in which the trapped
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...
is consumed. How closely the fodder is packed determines the nature of the resulting silage by regulating the
chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breakin ...
s that occur in the stack. When closely packed, the supply of oxygen is limited, and the attendant acid
fermentation Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food p ...
brings about decomposition of the
carbohydrate In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or ma ...
s present into acetic, butyric and lactic acids. This product is named sour silage. If the fodder is unchaffed and loosely packed, or the silo is built gradually,
oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...
proceeds more rapidly and the temperature rises; if the mass is compressed when the temperature is , the action ceases and sweet silage results. The
nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at sevent ...
ous ingredients of the fodder also change: in making sour silage, as much as one-third of the albuminoids may be converted into
amino In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent such ...
and
ammonium The ammonium cation is a positively-charged polyatomic ion with the chemical formula or . It is formed by the protonation of ammonia (). Ammonium is also a general name for positively charged or protonated substituted amines and quaternary ...
compounds; in making sweet silage, a smaller proportion is changed, but they become less
digestible Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma. In certain organisms, these smaller substances are absorbed through the small intest ...
. If the fermentation process is poorly managed, sour silage acquires an unpleasant odour due to excess production of ammonia or butyric acid (the latter is responsible for the smell of rancid butter). In the past, the fermentation was conducted by indigenous microorganisms, but, today, some bulk silage is inoculated with specific microorganisms to speed fermentation or improve the resulting silage. Silage inoculants contain one or more strains of
lactic acid bacteria Lactobacillales are an order of gram-positive, low-GC, acid-tolerant, generally nonsporulating, nonrespiring, either rod-shaped (bacilli) or spherical ( cocci) bacteria that share common metabolic and physiological characteristics. These bacte ...
, and the most common is ''
Lactobacillus plantarum ''Lactiplantibacillus plantarum'' (formerly ''Lactobacillus arabinosus'' and ''Lactobacillus plantarum'') is a widespread member of the genus ''Lactiplantibacillus'' and commonly found in many fermented food products as well as anaerobic plant ma ...
''. Other bacteria used include '' Lactobacillus buchneri'', ''
Enterococcus faecium ''Enterococcus faecium'' is a Gram-positive, gamma-hemolytic or non-hemolytic bacterium in the genus ''Enterococcus''. It can be commensal (innocuous, coexisting organism) in the gastrointestinal tract of humans and animals, but it may also be ...
'' and ''
Pediococcus ''Pediococcus'' is a genus of gram-positive lactic acid bacteria, placed within the family of Lactobacillaceae. They usually occur in pairs or tetrads, and divide along two planes of symmetry, as do the other lactic acid cocci genera ''Aerococcu ...
'' species. Ryegrasses have high sugars and respond to nitrogen fertiliser better than any other grass species. These two qualities have made ryegrass the most popular grass for silage-making for the last sixty years. There are three ryegrasses in seed form and commonly used: Italian, Perennial and Hybrid.


Pollution and waste

The fermentation process of silo or pit silage releases liquid. Silo effluent is corrosive. It can also contaminate water sources unless collected and treated. The high nutrient content can lead to
eutrophication Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phytoplan ...
(hypertrophication), the growth of bacterial or
alga Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mi ...
l blooms. Plastic sheeting used for sealing pit or baled silage needs proper disposal, and some areas have recycling schemes for it. Traditionally, farms have burned silage plastics; however odor and smoke concerns have led certain communities to restrict that practice.


Storing silage

Silage must be firmly packed to minimize the oxygen content, lest it spoil. Silage goes through four major stages in a silo: *Presealing, which, after the first few days after filling a silo, enables some respiration and some dry matter (DM) loss, but stops. *Fermentation, which occurs over a few weeks. pH drops, and there is more DM loss, but hemicellulose is broken down; aerobic respiration stops. *Infiltration, which enables some oxygen infiltration, allowing for limited microbial respiration. Available carbohydrates (CHOs) are lost as heat and gas. *Emptying, which exposes surface, causing additional loss; rate of loss increases.


Safety

Silos are potentially hazardous: deaths may occur in the process of filling and maintaining them, and several safety precautions are necessary. There is a risk of injury by machinery or from falls. When a silo is filled, fine dust particles in the air can become explosive because of their large aggregate surface area. Also, fermentation presents respiratory hazards. The ensiling process produces "silo gas" during the early stages of the fermentation process. Silage gas contains
nitric oxide Nitric oxide (nitrogen oxide or nitrogen monoxide) is a colorless gas with the formula . It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its ch ...
(NO), which will react with oxygen (O2) in the air to form
nitrogen dioxide Nitrogen dioxide is a chemical compound with the formula . It is one of several nitrogen oxides. is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year for use primarily in the producti ...
(NO2), which is toxic. Lack of oxygen inside the silo can cause asphyxiation. Molds that grow when air reaches cured silage can cause organic dust toxic syndrome. Collapsing silage from large bunker silos has caused deaths. Silage itself poses no special danger.


Nutrition

Ensilage can be substituted for root crops. Bulk silage is commonly fed to
dairy cattle Dairy cattle (also called dairy cows) are cattle bred for the ability to produce large quantities of milk, from which dairy products are made. Dairy cattle generally are of the species ''Bos taurus''. Historically, little distinction was mad ...
, while baled silage tends to be used for
beef cattle Beef cattle are cattle raised for meat production (as distinguished from dairy cattle, used for milk production). The meat of mature or almost mature cattle is mostly known as beef. In beef production there are three main stages: cow-calf operat ...
,
sheep Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus ''Ovis'', in everyday usage it almost always refers to domesticated ...
and
horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million ...
s. The advantages of silage as animal feed are several: *During fermentation, the silage bacteria act on the cellulose and carbohydrates in the forage to produce
volatile fatty acids Short-chain fatty acids (SCFAs) are fatty acids with fewer than six carbon atoms. Derived from intestinal microbial fermentation of indigestible foods, SCFAs are the main energy source of colonocytes, making them crucial to gastrointestinal health. ...
(VFAs), such as acetic, propionic, lactic, and butyric acids. By lowering pH, these produce a hostile environment for competing bacteria that might cause spoilage. The VFAs thus act as natural preservatives, in the same way that the lactic acid in yogurt and cheese increases the preservability of what began as milk, or vinegar (dilute acetic acid) preserves pickled vegetables. This preservative action is particularly important during winter in temperate regions, when green forage is unavailable. *When silage is prepared under optimal conditions, the modest acidity also has the effect of improving palatability and provides a dietary contrast for the animal. (However, excessive production of acetic and butyric acids can reduce palatability: the mix of bacteria is ideally chosen so as to maximize lactic acid production.) *Several of the fermenting organisms produce vitamins: for example, lactobacillus species produce
folic acid Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing and ...
and
vitamin B12 Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. It is one of eight B vitamins. It is required by animals, which use it as a cofactor in DNA synthesis, in both fatty acid and amino acid metabolism. I ...
. *The fermentation process that produces VFA also yields energy that the bacteria use: some of the energy is released as heat. Silage is thus modestly lower in caloric content than the original forage, in the same way that yogurt has modestly fewer calories than milk. However, this loss of energy is offset by the preservation characteristics and improved digestibility of silage.


History

Using the same technique as the process for making
sauerkraut Sauerkraut (; , "sour cabbage") is finely cut raw cabbage that has been fermented by various lactic acid bacteria. It has a long shelf life and a distinctive sour flavor, both of which result from the lactic acid formed when the bacteria f ...
, green fodder was preserved for animals in parts of Germany since the start of the 19th century. This gained the attention of French agriculturist Auguste Goffart of
Sologne Sologne (; ) is a natural region in Centre-Val de Loire, France, extending over portions of the departements of Loiret, Loir-et-Cher and Cher. Its area is about . To its north is the river Loire, to its south the river Cher, while the districts ...
, near
Orléans Orléans (;"Orleans"
(US) and
dairy farm Dairy farming is a class of agriculture for long-term production of milk, which is processed (either on the farm or at a dairy plant, either of which may be called a dairy) for eventual sale of a dairy product. Dairy farming has a history tha ...
ing in the United States suited the ensiling of green
corn Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The ...
fodder, and was soon adopted by
New England New England is a region comprising six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York to the west and by the Canadian provinces o ...
farmers. Francis Morris of Maryland prepared the first silage produced in America in 1876. The favourable results obtained in the US led to the introduction of the system in the United Kingdom, where Thomas Kirby first introduced the process for British dairy herds. The modern silage preserved with acid and by preventing contact with air was invented by Finnish academic and professor of chemistry Artturi Ilmari Virtanen. Virtanen was awarded the 1945 Nobel prize in chemistry "for his research and inventions in agricultural and nutrition chemistry, especially for his fodder preservation method", practically inventing modern silage. Early silos were made of stone or concrete either above or below ground, but it is recognized that air may be sufficiently excluded in a tightly pressed stack, though in this case a few inches of the fodder round the sides is generally useless owing to
mildew Mildew is a form of fungus. It is distinguished from its closely related counterpart, mould, largely by its colour: moulds appear in shades of black, blue, red, and green, whereas mildew is white. It appears as a thin, superficial growth consi ...
. In the US, structures were typically constructed of wooden cylinders to 35 or 40 ft. in depth. In the early days of mechanized agriculture (late 1800s), stalks were cut and collected manually using a knife and horsedrawn wagon, and fed into a stationary machine called a "silo filler" that chopped the stalks and blew them up a narrow tube to the top of a tower silo.


Anaerobic digestion

Silage may be used for anaerobic digestion.


Fish silage

Fish silage is a method used for conserving
by-product A by-product or byproduct is a secondary product derived from a production process, manufacturing process or chemical reaction; it is not the primary product or service being produced. A by-product can be useful and marketable or it can be consi ...
s from fishing for later use as feed in
fish farming upright=1.3, Salmon farming in the sea (mariculture) at Loch Ainort, Isle of Skye">mariculture.html" ;"title="Salmon farming in the sea (mariculture">Salmon farming in the sea (mariculture) at Loch Ainort, Isle of Skye, Scotland Fish farming or ...
. This way, the parts of the fish that are not used as human food such as fish guts (entrails), fish heads and trimmings are utilized as ingredients in feed pellets. The silage is performed by first grinding the remains and mixing it with
formic acid Formic acid (), systematically named methanoic acid, is the simplest carboxylic acid, and has the chemical formula HCOOH and structure . It is an important intermediate in chemical synthesis and occurs naturally, most notably in some ants. Es ...
, and then storing it in a tank. The acid helps with preservation as well as further dissolving the residues. Process tanks for fish silage can be aboard ships or on land.


See also

* Artturi Ilmari Virtanen *
Grain crimping Grain crimping or moist grain crimping is an agricultural technology, an organic way to preserve feed grain into livestock fodder by fermentation. Crimped grain brings health benefits to the animals and economic benefits such as cost savings an ...
* Mycoestrogen *''
Trifolium pratense ''Trifolium pratense'', the red clover, is a herbaceous species of flowering plant in the bean family Fabaceae, native to Europe, Western Asia, and northwest Africa, but planted and naturalized in many other regions. Description Red clove ...
'' *
Xenoestrogen Xenoestrogens are a type of xenohormone that imitates estrogen. They can be either synthetic or natural chemical compounds. Synthetic xenoestrogens include some widely used industrial compounds, such as PCBs, BPA, and phthalates, which have estr ...


References


Sources

*''Making and Feeding Silage'', John Murdoch, B.Sc, Ph.D. Published by Dairy Farmer (Books) Limited, Lloyd's Chambers, Ipswich, UK 1961)
Feeding baleage to horses – the ultimate guide – Horsetalk.co.nz
* "The Owner-Built Homestead" by Barbara and Ken Kern, New York: Scribner, 1977.


Further reading

* Zhou, Yiqin. ''Compar son ofFresh or Ensiled Fodders (e.g., Grass, Legume, Corn) on the Production of Greenhouse Gases Following Enteric Fermentation in Beef Cattle''. Rouyn-Noranda, Qué.: Université du Québec en Abitibi-Témiscamingue, 2011. ''N.B''.: Research report. {{Authority control Anaerobic digestion Fodder