Animal feedis food given to domestic animals in the course of animal husbandry. There are two basic types: fodder and forage. Used alone, the word “feed” more often refers to fodder.
As long aslivestockremains an integral part of agricultural society, there will always be the demand for animal feed on a large scale. With a large variety of livestock, from cows to chickens to horses to ducks, there must also be a large variety of different feed to accommodate their individual needs.
Basics
The commercial sale and industrial production of animal feeds has a history dating back as far as the 1800s. It was during this time period that the significance of balanced diets and nutrients in the diets of humans and animals was beginning to make steam as a mainstream ideology. One of the first big feed producers, which was the first to manufacture corn gluten feed, was calledPurinaand was established in 1882. It expanded its operations near the beginning of the 20th century and still operates today. In modern times, there are three major types of feed used by farmers, each with their own uses and benefits.
1.Compound Feed
One of the most common types of feeds used by commercial farmers is compound feed. Also known asfeedstuffs, they are blends of various additives and raw materials that are formulated to specifically suit the intended animal. They are often produced as pellets or crumbles.
Like modern vitamins with humans, they can be used to either satisfy the complete nutritional requirements of their target animals or as a supplement to other staples of the animals’ diets. They are often complemented with extra vitamins and minerals. It is produced in astronomically large amounts, with over 600 million tons produced annually on a global scale.
Compound feed is fodder that is blended from various raw materials and additives. These blends are formulated according to the specific requirements of the target animal. They are manufactured by feed compounders as meal type, pellets or crumbles. The main ingredients used in commercially prepared feed are the feed grains, which includecorn, soybeans, sorghum, oats, and barley.
Compound feed may also includepremixes, which may also be sold separately. Premixes are composed of microingredients such as vitamins, minerals, chemical preservatives, antibiotics, fermentation products, and other essential ingredients that are purchased from premix companies, usually in sacked form, for blending into commercial rations. Because of the availability of these products, a farmer who uses his own grain can formulate his own rations and be assured his animals are getting the recommended levels of minerals and vitamins.
2.Fodder
“Fodder” refers particularly to foods orforagesgiven to the animals (including plants cut and carried to them), rather than that which they forage for themselves. It includes hay, straw, silage, compressed and pelleted feeds, oils and mixed rations, and sprouted grains andlegumes.Feed grainsare the most important source of animal feed globally. The amount of grain used to produce the same unit of meat varies substantially.
According to an estimate reported by the BBC in 2008, “Cows and sheep need 8kg of grain for every 1kg of meat they produce, pigs about 4kg. The most efficient poultry units need a mere 1.6kg of feed to produce 1kg of chicken.” Farmed fish can also be fed on grain, and use even less than poultry. The two most important feed grains are maize and soybean. Other feed grains include wheat, oats, barley, and rice, among many others.
Fodder, is used primarily to feed domesticated livestock such as goats, sheep, cattle, horses and pigs. It is typically composed of plant matter like hay, straw and grains. The term is used to describe these plants being given to the animals after the plants have been harvested, which contrasts with forage, as will be explained below. Meat and bone meal are occasionally mixed into fodder, which has been frequently blamed for the spread of mad cow disease and has been banned in many countries.
Hay is one type of fodder as animal feed
Traditional sources of animal feed include household food scraps and the by-products of food processing industries such as milling and brewing. Material remaining from milling oil crops like peanuts, soy, and corn are important sources of fodder. Scraps fed to pigs are calledslop, and those fed to chicken are calledchicken scratch.Brewer’s spent grainis a by-product of beer making that is widely used as animal feed.
Animal Feed -pelleted fodder
Forage
“Forage” is plant material (mainly plant leaves and stems) eaten by grazinglivestock. 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 as hay or silage.
Unlike fodder, which is harvested plant matter fed to animals in bunches or bales, forage is plant matter that is literally grown in a confined area with the intention of having it grazed upon by various livestock. It can be composed of legumes, grasses, corn, oats,alfalfaand other edible plants. The act of eating or grazing upon the plant matter is known as foraging.
Matterexists either as in form of an element, compound or a mixture. An element is the simplest form of a substance because is made up of one type of atoms. Elements can further be classified into metals and non-metals. Compounds are formed between two or more elements that have chemically combined. Many different substances out there do exist as compounds.
A mixture is a combination of two or more substances that have not chemically combined. This implies that they can easily be separated using physical means. Some common methods of separating mixtures are distillation, evaporation, filtration, chromatography, centrifugation, magnetization, crystallisation and decanting.
Elements, Compounds and Mixtures illustration
ELEMENTS
The simplest form of a substance is called an element. It cannot be split into other simpler substances by any chemical process. An element is made up of only one kind ofatom. There are 115 elements and 24 of them do not occur in nature. They form what we have as the periodic table. The elements are classified into metallic and non-metallic categories.
Metals often have high density, high melting points, highboiling points, malleable, ductile, shiny (lustrous), high thermal and electrical conductivity. Non-metallic elements have low values for the stated characteristics. Each element is given a special chemical symbol to characterize it, e.g. Carbon (C), Sulphur (S), Sodium (Na), Potassium (K), Chlorine (CL) and Lead (Pb).
Symbols consists of one or two letters of the alphabet, the first being capital letter- A, B, C. Several elements with the same initial letter, a second letter or subsequent letter is added e.g. C for carbon, calcium (Ca), Chlorine (Cl). Other use Latin names e.g. sodium (Na) from natrium, lead (Pb) from plumbum etc
Isotopes
The number of electrons in an atom is equal to the number of protons. The number of protons in an atom gives the atomic (proton) number for that atom. The number of neutrons for the same element is often equal. When atoms for an element have the same number of protons (same number of electrons), with the same chemical properties but the number of neutrons vary, one atom type is stable while the other atom is called an isotope for the stable atom. They however show different physical properties.
Some examples of elements with isotopes are Cl (35, 37), H (1, 2, 3), C (12, 13, 14), O (16, 17)
Allotropes
Some substances can crystallize in two or more forms. Some of these substances are unstable in one form and therefore change from one form to another under some circumstances. In situations where they change form due totemperature, the specific temperature under which they change is called the transition temperature. Some allotropes include
Calcium Carbonate (Calcite and aragonite)
Iodine mono-chloride (red, brown)
Sulphur (rhombic, monoclinic)
Phosphorous (red, white, black).
Carbon (amorphous, graphite, diamond).
Oxygen (02, Ozone)
“fin (grey, white)
Allotropes always exhibit different physical properties and at times they may have even different chemical properties. These properties make the allotropes be used for different purposes.
COMPOUNDS
Compounds are pure substances which are formed due to a chemical reaction between l wo or more elements. When a new substance is formed during the chemical reaction, chemical change takes place. This combining of elements can be represented by word equation:hydrogen + oxygen → water. Water molecules contain two atoms of hydrogen and one atom of oxygen and hence the chemical formulaH2O.
The formula of a compound is made up from the symbols of the elements present and the ratio in which the different atoms are present.Carbon dioxidehas the formula CO2. This shows that it contains one carbon atom for every two oxygen atoms. The 2 shows that there are 2 oxygen atoms present in each molecule of carbon dioxide.
Compounds are made up of fixed proportion of elements: They have a fixed proportion. Chemists call this the “Law of constant composition”. The forces that hold atoms together in compounds are called “Chemical bonds”. Reaction between elements and oxygen is called an oxidation reaction as the substance gains oxygen. Some examples
2Mg (S) + O2(g) → 2MgO(S
C(s) + O2(g)→ CO2(g)
When substances react such that there is a loss of oxygen, the process is called reduction. Some examples:
CuO (S) + H2(g)→Cu(S) + H20(g).
Fe2O3(S) + 3CO(g) → 2Fe(S) + 3CO2(g)
Look at theseREDOXreactions
This is an example of oxidation reaction
Carbon + Oxygen → Carbon dioxide
C(s) + O2(g) → CO2(g)
Oxidation reaction is gain of oxygen, loss of hydrogen or electrons.
This is an example of a reduction reaction
Copper Oxide + Hydrogen → Copper + Water
CuG(s)+ H2(g) → Cu (S) + H2O(g)
deduction reaction is loss of oxygen, gain of hydrogen or electron.
MOLECULES
The atoms are joined together in small groups. These small groups are called“molecules”.For example the atoms of Hydrogen, Iodine, Chlorine, Nitrogen, Oxygen, Fluorine and Bromine are each joined in pairs and are known as “diatomic”molecules, Phosphorus atoms are joined in four and sulphur in eight. In chemical shorthand the molecule of Chlorine is written s Cl2.
The gaseous element helium, neon, argon, krypton, Xenon and Radon are composed of separate and individual atoms. They are “monatomic”; they are shorthanded Ne, Ar, Kr, Xe and Rn respectively.
Molecules are not always formed by atoms of the same type joining together. For example, water exists as molecule containing Oxygen and hydrogen atoms.
MIXTURES
Mixtures contain more than one substance (element or compound). The substances of the mixture have their specific physical properties. Our world is very complex, owing to the vast range of pure substances available, and to the variety of ways in which these pure substances can mix with each other. In everyday life we do not ‘handle’ pure substances very often.
The air we breathe is not a single, pure substance – and we could not live in it if it were! Water would be rather tasteless if we drank it distilled – indeed, some companies do market distilled water that has had salts added back to it.
It is therefore possible to separate these substances provided there are suitable differences in their physical properties. If the mixture is made to undergo a chemical reaction, then separation thereafter becomes more complicated.
Types of mixtures
Mixtures may be Homogeneous or Heterogeneous
Ahomogeneous mixture hasthe same composition of elements/or compounds throughout – evenly distributed. It is also called solution. An example of such a mixture is copper II sulphate solution.
Aheterogeneoushas different regions or areas with different compositions and properties – not evenly distributed. An example of such a mixture is concrete.
Each mixture must be made from at least two parts, or phases, which may be solid, liquid or gas.
Element, Compound and Mixtures – Cooling curve
The temperature stays constant while the gas condenses, and while the liquid freezes. A cooling mixture of ice and salt could be used to lower the temperature below 0 °C.T
There are a number of different ways in which the three states can be combined. In some, the states are completely mixed to become one single state or phase – ‘you cannot see the join’. This is ahomogeneous mixture. Technically, the term ‘solution’ is used for this type of mixture. Solid salt dissolves in liquid water to produce a liquid mixture – a salt solution. In other types of mixture, the states remain separate (aheterogeneous mixture). One phase is broken up into small particles, droplets, or bubbles, within the main phase.
Solutions and homogeneous mixtures
Table 2.3 shows us some of the ways in which substances in different states can combine. Perhaps the most important idea here is that of one substance dissolving in another – the idea of asolution. We most often think of a solution as being made of a solid dissolved in a liquid. Two- thirds of the Earth’s surface is covered by a solution of various salts in water. The salts are totally dispersed into the water and cannot be seen. However, other substances that are not normally solid are dissolved in sea water. For example, the dissolved gases, oxygen and carbon dioxide, are important for life to continue in the oceans.
Less obvious perhaps, but quite common, are solutions of one liquid in another. Alcohol mixes (dissolves) completely with water. Beer, wine and whisky do not separate out into layers of alcohol and water (even when the alcohol content is quite high). Alcohol and water are completelymiscible: they make a solution.
Particle arrangement in a pure liquidParticle arrangement in a mixture of two miscible liquids
+
When a solute dissolves in a solvent, the solute particles are completely dispersed in the liquid.
Table 2.3 Important examples of different types of mixture
Type of mixture
Mixture
Description
Examples
Homogeneous mixtures (solutions)
Solution * of solid in liquid
transparent solution of solid dissolved in liquid
sea water, sugar in water, salt solutions
Solution of two miscible liquids
single layer of transparent liquid
vodka (alcohol and water), two- stroke motor oil (petrol and oil)
Solution of gas in liquid
transparent solution of gas dissolved in a liquid
mineral and soda waters, champagne, ‘fizzy’ soft drinks
Mixture of gas in gas
transparent mixture of two or more gases
air
Alloy of two solid metals
solid, evenly spread mixture of two metals
brass, bronze
Heterogeneous mixtures
Suspension of solid in liquid
cloudy mixture of solid particles suspended in a liquid
river water carrying mud and silt, flour in water, kaolin indigestion medicine
Gel
jelly-like mixture of solid and liquid, liquid trapped in the solid
fruit jelly, agar gel
Emulsion of two immiscible liquids
cloudy mixture of tiny drops of one liquid suspended in another liquid
skin cream, milk, salad dressing, mayonnaise
Aerosol of either a liquid or solid in a gas
small droplets of liquid, or particles of solid, dispersed in a gas
liquid-in-gas: mist, clouds, paint spray
solid-in-gas: smoke, dusty air
Foam of gas in liquid
many small bubbles of gas trapped in liquid
washing lather, froth or ‘head’ on beer, shaving foam
Solid foam of gas in solid
many small bubbles of gas trapped in a solid
polystyrene foam, foam rubber, bread, sponge cake
These solutions are particularly important in chemistry.
Technically the air itself could be described as a solution of several gases in nitrogen, though this would be an unusual everyday use of the term. However, it is interesting to note that different gases always mix completely with each other. Likewise, alloys are homogeneous mixtures of metals, though we do not usually call them solutions. They are made by mixing the liquid metals together (dissolving one metal in the other) before solidifying the alloy.
Suspensions and heterogeneous mixtures
There are a great number of combinations of substances that do not mix: solids that do not dissolve in water; liquids that do not mix with each other (they areimmiscible). Flour does not dissolve in water but forms aslurryorsuspension. The particles of solid are simply dispersed (spread) throughout the water and will eventually settle out if left to stand. Sand does not dissolve in water either. The ocean tides shift and deposit it on beaches and sandbars throughout the world. The great estuaries such as the Nile or Mississippi deltas are silted up by suspended soil deposited from the river.
Oil and water do not mix. Salad dressing made from olive oil and vinegar (a mixture of ethanoic acid and water) will settle out into two layers. When shaken, it forms anemulsionwith droplets of oil suspended throughout the vinegar. Unlike pure liquids, emulsions are cloudy (opaque) so you cannot see through them. To stop an emulsion, such as mayonnaise, separating out into layers, anemulsifieris added.
This prevents the small droplets of oil coming together to form larger droplets and then a separate layer. In traditional mayonnaise the emulsifier is egg yolk, which contains lecithin. Other food products contain other emulsifiers. In the European system for labelling food additives, emulsifiers are given E numbers from E322 to E494. E322 is lecithin.
The world of cosmetics is full of examples of emulsions. Skin moisturising creams are emulsions of oils in water; the oils prevent the skin from drying out. It is possible to switch the balance of the two phases in a cosmetic preparation. Cold cream and cleansing cream are emulsions of water in oils. They have an oilier‘feel’or texture than hand or face creams.
There are two ways in which mixtures can be formed between different substances:
homogeneous mixtures,where the substances are totally mixed together and are indistinguishable – examples include solutions of salts and sugars in water.
heterogeneous mixtures,where the substances remain separate and one substance is spread throughout the other as small particles, droplets, or bubbles – examples include suspensions of insoluble solids in water.
Differences between Mixtures and Compounds
Mixture
Compound
The constituent substances can be separated from one another by physical methods
The constituent elements cannot be separated by physical method, chemical reaction is necessary.
Mixture may vary widely in composition
Compounds are fixed in their compositions by mass of the elements present
Mixing is not usually accompanied by external effects such as explosion, evolution of heat or volume change for gases
Chemical change is usually accompanied by one or more of these effects
The properties of the mixture are the sum of the properties of the constituents of the mixture.
The properties of a compound are peculiar to it and are usually very different from the properties of the constituent elements.
Colloids and suspensions
The heterogeneous mixtures listed in table 2.3 can be divided into two types – suspensions and colloids. The difference depends on the size of the particles suspended, or dispersed, in the surrounding medium.
Suspensionscontain relatively large particles (over l000nm, where 1 nm = 10-9m) of an insoluble solid, or droplets of an insoluble liquid. In time, the particles or droplets settle out.
Colloidscontain smaller particles (1-1000nm) and take various forms. Emulsions, sols, gels, aerosols and foams are all examples of colloids. The particles of a colloid are too small to be seen by eye, but they do scatter light.
Colloids fill an important place in our lives. Our blood contains proteins spread throughout a watery medium; milk is a complex colloid containing fat droplets and proteins dispersed in water. We also manufacture a large number of colloids to serve a wide range of purposes. ‘Emulsion’ paint is an example of a colloidal system.
In white ‘emulsion’ paint, the dispersed particles are solid (for example titanium(iv) oxide particles), mixed up in water but not dissolved in it. A true emulsion is made from one liquid dispersed in another. ‘Emulsion’ paint is not in fact a true emulsion. Nor is the photographic ‘emulsion’ coated on films. The light-sensitive layer of a film consists of fine crystals of silver bromide trapped in a gelatine gel.
Every colloid has at least two parts :
thedispersed phaseis split into very small particles – for example the fat in milk or the water droplets in mist.
thecontinuous phasecontains the dispersed phase spread throughout it – for example the water in milk or the air in mist.
Table 2.4 The dispersed and continuous phases of different types of colloid
