Feed and Feeding Goats are animals known to convert low quality fibrous vegetation into useful products for man. These include meat, milk, skin and manure.
Goats prefer a varied diet and to be able to wander and browse a broad range of plants. In traditional systems they make good use of the available vegetation. Because of their browsing habit they are often able to exist in areas of low rainfall and poor growth, where cattle and even
sheep would not prosper. If their numbers do not become excessive, a good ecological balance can be maintained.
Goats, being inquisitive eaters, will eat all types of vegetation as well as articles which have little feed value, such as cardboard and human hairs.
However, given the opportunity, they seek good pasture where they can select the grasses they prefer. They will often reject the legume clover which is favoured by sheep and cattle. This means that combining sheep and goats to graze in a single flock does not necessarily lead to
competition between the two species. Where a wide range of plants is available it is possible to keep more animals on a given area of land because each species grazes on a different type of vegetation.
Goats are ruminants. This means they have four – stomach digestive system which comprises rumen, reticulum, omasum and abomasum in the adult goat with which they extract nutrients from fibrous materials using bacteria and protozoa that live in the rumen and reticulum. Feed is initially chewed in the mouth and mixed with saliva before it passes to rumen. This material is returned to mouth for further chewing so that the
particle size is reduced, speeding up subsequent digestion. This regurgitation is called chewing the cud. Like all ruminants goats can be seen chewing and re- chewing this material between grazing periods.
They chew the cud more at night than during the day. After thoroughly chewing cud the feed passes to rumen and reticulum, where micro organism break it into simple chemicals which are either absorbed into the body or are used by the micro –organism to reproduce.
The populations of micro-organisms break it into simple chemicals which are either absorbed into the body or are used by micro –organism found in the gut. Digestive microbes are specific to particular diets and gradually change in response to changes in the types of feed being eaten.
If a sudden change of diet occurs the system is upset because the micro organisms cannot digest the new feeds. It takes days for the appropriate micro-organism populations to build up to cope with the new diet. The sudden introduction of a new feed can lead to scouring and loss of condition or even death in severe cases. For goat keepers, this means that any change in diet must be very gradual. A new feed should be given in very small amounts at first, with the quantity being increased progressively over a period of days.
The liquid mixture of rumen and reticulum passes to the omasum, where most of the water removed, and then to the abomasums. This stomach is very acidic and any micro-organism reaching it is killed. Digestion from this point progresses with the addition of enzymes which are secreted from the gut wall. The digestive contents are now broken down into nutrients that are useful to the body. These are absorbed by the small intestine. This part of the gut is very long but is accommodated as a series of coils so it takes up as little room as possible. More of the water is removed in the large intestine before the very dry dung pellets are expelled from the rectum through the anus. Goats are able to extract almost all of the water from the contents of the digestive system, which means they can make very efficient use of whatever water is available.
This is one of the reasons why goats can survive in arid regions. It is considered a sign of good health if the dung is reasonable dry.
Feed intake
In the tropics, dairy goats will eat up to the equivalent of 4-5 per cent of their own body weight in dry matter daily. Meat goats will consume about three per cent. In cooler parts of the world dairy goats have been known to eat up to eight per cent. Goats have a much better capacity for forage than sheep of a similar size. How much a goat eats depends on its:
• Age
• Breed
• Production capacity, or
• Whether it is pregnant or lactating.
Younger goats eat more than older ones because they are growing.
Pregnant and lactating animals consume more than non-pregnant and non-lactating ones because they need more feed to produce milk and to enable the foetus to grow.
Goats with free access to feed will vary their intake depending on the energy available from the feed. One average bigger goats eat more than smaller ones. All goats will eat more if the feed is in a fine rather than coarse form. The goat keeper can influence how much goats eat by:
• How finely ground the feed is; and
• How much useful energy the feed has (measure in ME per kg DM)
If hay or straw is chopped, more will be eaten than if fed without chopping. Finely chopped straw is often fed as part of a concentrate ration. More feed is eaten if the feed has a high energy density. So if a
high-energy feed such as or molasses is mixed with a fibrous feed such as straw, goats will eat more.
Feed intake is generally measured in dry matter terms. Dry matter (DM) is the amount of feed remaining when all the water has been removed. It is used as a guide to how much fresh or moist feed can be fed.
Feeding example 30 kg goat
A 30 kg goat requires:
1. For maintenance 1.6% DM as % live weight = 0.5kg
2. For production 3.0% DM as % live weight = 0.9kg
1.4kg
If DM of feed is 25% four times as much is needed to achieve a set target figure, therefore:
• 1.4 x 4 = 6.4 kg fresh material daily
Nutrients
Much of the information used to calculate nutrient requirements for goats is based on research with sheep and cattle.
For goats you need a balance of five basic components.
1. energy
2. protein
3. vitamins
4. minerals
5. water
All goats have a basic need (maintenance) for energy nutrients but some will also require additional (production) nutrients at particular times, for example, nannies in the final stages of pregnancy or when lactating or kids when they are growing.
The energy from feed is used by the goat for maintenance. Maintenance energy is that amount needed to maintain the animal in a stable body condition and provide enough energy for walking. Production is that required for growing and for producing milk or a foetus. It is required over and above the energy for maintenance. Not all energy in feed can
be used by the goat and so only the part that, the metabolisable energy (ME) part, is used to calculate how much energy is needed for a goat’s maintenance and production.
Energy is measure in Mega joules (MJ) or calories. (One calories = 4.2 joules). An average diet contains about 8.5 Mega joules (MJ) of Metabolisable Energy (ME) per kilogram of dry matter (DM). However,
the amount may range from 6 to 13 MJ/ME/kg DM.
To estimate the amount of ME in a feed it is necessary to undertake a feeding trail to find out the digestibility measures of that part of the feed which is absorbed from the digestive tract into the body. There is direct relationship with ME, shown as:
• ME = 0.15 X DOMD
ME is in mega joules per kilogram of dry matter (Mj/kg DM). DOMD is digestibility of organic matter in the dry matter.
Alternatively, small amounts of feed can be placed in an animal’s rumen in a small bag and the amount absorbed recorded over a period of time.
Very few of either of these measurements have been undertaken with goats in the tropics, so the amount of information specifically applicable to goats is limited. In consequence, calculations for nutrition often have and also often based on data from the temperate regions of the world
rather than the tropic.
Table below has been derived from experiments undertaken in the tropics and gives a guide to daily amounts of energy required by goats of different weights kept under different husbandry systems.
For pregnant or lactating females or growing kids energy is required over and above the amount needed to maintain body condition given in Table 9.3
For lactation the energy (ME) required relates to the energy content and composition of the milk produced. A typical energy requirement is shown below:
Pregnant goat requires sufficient energy to feed the growing foetus or fetuses. In the last part of pregnancy the female’s requirement rises substantially and particularly if she is carrying two or three kids. Other nutrients follow a similar demand curve. The quality of feed and its
energy density must rise in this part of the pregnancy if the kids are to be born at a reasonable weight. If the nanny receives too little energy she will become thin as her own body reserves are used to grow the kids.
She may develop pregnancy toxemia (ketosis) and die if the situation gets worse. Levels of energy intake are also required to achieve sexual maturity and for successful conception.
For growth the level of energy available to growing kids depends on the rate at which they grow. Research in East Africa suggests 0.035 MJ/ME is required per gram of growth. A 20 kg animal gaining 50g daily requires 1.75 MJ/ME for growth.
All goats should have a minimal level of crude protein each day. Crude protein (CP) is calculated from the nitrogen content of a feed.
1. CP = nitrogen x 6.25
(It is expressed as a percentage (%))
Protein can also be synthesized from non-protein nitrogen such as urea.
The crude protein content of a feed is calculated in the laboratory and, in temperate countries, tables are available showing values for many feeding materials. This is infuriately, not the case with most tropical feedstuffs. Much less is known about specific protein requirements for goats in the tropics. Figures that relate to sheep are commonly used instead (Table9.5).
So if a very high fibrous diet (e.g. straw) is fed it may be low in protein.
Additional crude protein, such as fish or oilseed meals, should then be added to the feed as a supplement.
A 35-40 kg doe requires about 30g/day DCP (Digestible crude protein) for maintenance. For pregnancy and lactation this rises to 70g/day. For growing kids the requirements vary with size of kid and daily rate of growth. A 10 kg kid gaining 100g/day would need some 30g DCP
whilst one at 30g would need 50g/day.
Vitamins
Little research has been done on the vitamin requirements of goats and on vitamin deficiencies in tropical diets. In many situations goats do not suffer from a lack of vitamins where they have access to pasture or rangeland. Most diets have sufficient vitamin A (carotene), Vitamins D and K if green vegetation is available. If vitamin B12 is deficient, as characterised by anemia, loss of appetite and poor growth goats should be given cobalt, which will assist intestinal micro flora to synthesis the vitamin. Vitamin C does not need to be added to the diet as the goat is
able to synthesize sufficient for its needs.
Minerals
Minerals are important in the diet to keep goats healthy. There are two groups of minerals. Macro mineral nutrients (major) are in relatively large amounts while micro minerals (minor) are needed in very small
quantities. The minerals needed in goat diets are given below:
soils suffer from mineral deficiencies or have minerals that are not available to plants and so are not ingested by goats. Copper, cobalt and selenium are good examples. If goats receive insufficient copper they grow slowly and kids may be born unable to walk on their back legs.
Giving copper to the nanny can prevent this condition, but care must be taken not to overdose, since this may lead to death from copper poisoning. The only exact way of knowing whether a goat is short of
copper is to take a blood sample and have it analyzed.
One method of giving copper is by an injection under the skin twice yearly. Alternatively, boluses can be given to the goat to swallow. These remain in the stomach and slowly release copper over a six-month easiest solution to most minor mineral deficiency problems is for goats
to have access to a composite mineral lick. These can be purchased from feed companies or sometimes local rocks or salt blocks are available. In intensive systems minerals can be added to the concentrates feed.
Selenium and cobalt can be added to the concentrates feed. Selenium and cobalt can be given as a liquid drench to counter any deficiency of these mineral.
Calcium (Ca) and phosphorus (P) are important minerals in milk production and a lack of calcium in the diet may lead to milk fever in newly-kidded nannies. This condition can be fatal. As a guide 0.9g of Ca and P should be available per 1kg of milk produced.
Mineral toxicity or deficiencies are less commonly seen in an acute form than a chronic one. Copper deficiency, when most severe, will produce swayback in kids. Where the deficiency or toxicity is less severs, more chronic symptoms include:
• scouring
• poor fertility
• hair loss
• Poor appetite and growth.
Because these are also normal indications of poor nutrition and parasite infestation, identifying mineral deficiencies is difficult and best confirmed by the analysis of blood samples.
Water
All animal require access to water to enable them to perform normal body functions. This should ideally be fresh and clean. The more continuous the access the better the animal’s metabolism performs and the higher its production. In practical terms, however, watering animals usually takes place once or twice daily or even very other day.
The amount of water needed by a goat depends upon:
• Amount of dry matter eaten
• Whether the goat is lactating
• Air temperature
• Drinking frequency
• Water temperature.
If goats eat succulent feeds, which have high moisture content, they
need to drink less than they do when fed on dry feed. In desert conditions they will lick the dew from the trees. If water is cool or available at all times goats will drink less. In hot conditions goats keep cool by seeking shade under trees or rocks and will pant and sit when the air temperature exceeds 390
c. Panting causes loss of heat by evaporations of water from the lungs. Indigenous goats have a reputation for being very tolerant to heat stress and having a reduced demand for water. Long or shiny coats are thought to help protect the skin from the sun’s heat. Exotic breeds, on the other hand, are less adaptable and tend to eat less in hotter conditions which leads to body weight losses.
Compared with sheep, goats pant less and lose less water in the faeces and urine.
To achieve maximum efficiency, goats need to drink 4kg of water for every 1kg of dry matter they consume.
Water is more critical for growing kids and pregnant or lactating nannies than it is for other goats. The smaller an animal is the more water it needs relative to its size. This is because it has a large body surface in relation to its body size which makes it susceptible to heat stress.
Goats tend to thrive better than sheep under difficult range conditions because they are able to tolerate brackish or salty water which is often found in high temperature areas or near the sea. For example, salt concentrations of 10,000 ppm (parts per million) in the water are well tolerated.
In arid regions or in the dry season the number of watering places declines and flocks may have to travel long distances to drink and then wait their turn behind herds of larger camels or cattle. This reduces time available for grazing as well as causing overgrazing around waterholes.
Supplementation
Most farmers in the tropics cannot afford to give their goats any feed over and above what the animals can graze. By being able to select particular plants, goats may be able to increase the quality of their diet, especially with regard to energy or protein levels. In practice, their diet consists almost entirely of low-valve roughages. In these situations feeding a supplement to the diet can have a dramatic effect on productivity especially during the dry season, during late pregnancy or where animals are still fed.
Supplement can be given as:
• Concentrates containing extra energy (molasses, cereals)
• Protein source (legumes)
• Non-protein nitrogen (urea)
• Minerals/vitamins (salt licks).
Supplementary feeding is a costly exercise and only worthwhile if the improvement in performance gained it greater than the cost. If feeding pregnant nannies in the final month of gestation gives larger kids that grow well and can be sold for higher prices then supplementation may be worth doing. This is especially so if the supplementation is cheap to obtain. Tree fodder is one example and agricultural by-products may be the other.
Practical feeding
In practical terms the following period are important ones to consider when feeding goats:
• Bucks and nannies 1 month before mating
• Nannies for the 3 weeks after mating
• Nannies the final month before kidding
• First 2 months of lactation
• Growing kids, especially post weaning.
Only in selected situations are concentrates likely to be either available
or given as a supplement. More likely supplements are legumes or crop residues. These might include leucaena, stylos, pigeon peas, sweet potato stems/leaves, groundnut haulm and cassava leaves.
When not being used for mating, bucks do not normally need supplementary feed. A small quantity of concentrate in the 3-4 week period before breeding will help build up body condition of bucks. This is important if the males have many nannies to mate or if climatic conditions are harsh. Bucks can lose a great deal of weight during the mating period.
Feeding nannies immediately before and for three weeks after mating keeps them in good condition and will help the implantation of fertilized eggs in the uterus.
By far the most critical period during which correct feeding is important for the nanny is the last month of pregnancy when the foetuses are growing very rapidly and causing a severe strain on the mother’s body reserves. Reducing the ration immediately after kidding and then
building it up again for the first three weeks of the lactation until weaning, will encourage good milk production.
If nannies are in very poor condition at weaning, supplementary feeding will enable them to regain body condition and to be in a good state for mating and conception. It is hard to justify the cost of feeding kids concentrates. Supplementary feeding of kids after weaning will stop
them losing weight that often occurs when the nannies’ milk is no longer available to them.
3.5 Feeding and Grazing Behaviour of Goats
Many parts of the tropics have long periods when little or no rain falls
consequently vegetations dies back and surface water disappears.
The quantity of the vegetation also declines, with the best being eaten first.
The longer the dry period lasts the poorer the quality of the roughage becomes (Fig 3.2). Goats will then eat less of this material. If the nutrients in the feed are less than required for an animal’s maintenance it will begin to lose weight as body reserves are depleted.
As this happens the females will become anoestrus and so not breed.
Nannies that are already pregnant will produce very weak kids. In very long dry seasons animals will die, with the youngest, weakest and oldest dying first.
Goat keepers may counter these adverse effects by feeding goats on tree leaves or legumes. This practice can lead to deforestation problems when many animals are kept. This has happened in some areas of the third world such as Nepal and the Sahel region of Africa.
Goats are selective and agile feeders. They will walk long way searching for feed and are happier having a range of vegetation available to them including trees, shrubs and grasses. Shoots and leaves are preferred to stem. In intensive unit, if not managed effectively, goats will refuse and spoil a high percentage of forage offered.
When goats are first let out on to pastures in the mornings they will initially graze unselectively but then start to wander and become increasingly selective. Unlike sheep, goats will scatter and graze and
browse individually, climbing trees or standing on their hind legs to browse at higher levels. They will stop grazing if disturbed, for example, by rain. In hot conditions goats favour grazing in the early morning and evening. In Arabia they will graze at night if allowed, preferring to seek out comfortable shade during the heat of the day.
Where goat keepers can control their animals under extensive system they may be able to use range better if they allow sheep and goats to graze together. These two species are complementary in habit which means more animals may be kept in a set area. The sheep will graze the lower grasses whilst the goats will browse shrubs and trees.
Good goat keepers will know the browsing habits and movement patterns of the flock and their favourite watering and sheltering spots.
They will allow natural resting times in the middle of a day and know when to move the flock. Goats are much more difficult to move during cold, wet or windy periods.
Goats change their feeding habit between seasons. In the dry season they will eat bushes and trees which in wetter periods they would ignore, preferring in this season grasses and legumes. They can distinguish bitter, sweet, salty and sour tastes and show tolerance to bitter and salty tastes.
Although goats do not flock together in the way that sheep do, they do have a good herd instinct and if handled frequently become used to being moved or herded in large groups. Calling to animals in specific sound or tonation when feeding, will teach them to move together for handling.
Identifying the dominant females and males whom others will follow can also be useful.
Agro-industry by-products Industries that process agricultural produce often leave residues by products that can be fed to animals. The feeding value of such by
products varies considerable. Some examples are listed in Table 9.7 but the same product’s feeding value will change with different samples feeding a product to a small number of goats to observe the effect is one solution to this problem. Some by-products, such as molasses and
cassava, are high in energy but low in protein whilst others, such as linseed meal or desiccated cotton seek cake, have good levels of both protein and energy.
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