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Goats
offer an opportunity to more effectively convert pasture nutrients
to animal products such as milk, meat, and fiber which are currently
marketable and in demand by a growing segment of the US population.
In addition, goats selectively graze unwanted vegetation in pastures
and forests, thus providing biological control which will reduce
dependence on certain chemicals.
Goats consume only the most nutritious parts of a wide range of
grasses, legumes, and browse plants. Browse plants include brambles,
shrubs, trees, and vines with woody stems. The quality of feed on
offer will depend on many things, but is usually most directly
related to the age or stage of growth at the time of grazing. The
nutrient composition for several common feed types is shown in Table
One.
Grazing Behavior
Goats are very active foragers, able to cover a wide area in search
of scarce plant materials. Their small mouths and split upper lips
enable them to pick small leaves, flowers, fruits, and other plant
parts, thus choosing only the most nutritious available feed.
The ability to utilize browse species, which often have thorns and
an upright growth habit with small leaves tucked among woody stems,
is a unique characteristic of the goat compared to heavier, less
agile ruminants. Goats have been observed to stand on their hind
legs and stretch up to browse tree leaves or throw their bodies
against saplings to bring the tops within reach.
The feeding strategy of goats appears to be to select grasses when
the protein content and digestibility are high, but to switch to
browse when the latter overall nutritive value may be higher. This
ability is best utilized under conditions where there is a broad
range in the digestibility of the available feeds, giving an
advantage to an animal which is able to select highly digestible
parts and reject materials which are low in quality.
Grazing goats have been observed to:
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select grass over clover
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prefer browsing over grazing pastures
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graze along fence lines before grazing the center of a pasture
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graze the top of pasture canopy fairly uniformly before grazing
close to the soil level.
Because of their inquisitive nature and tolerance of “bitter” or
high tannin material, goats may eat unpalatable weeds and wild
shrubs that may be poisonous, such as cherry and milkweed. The
absence of the severity of poisoning is related to the quantity of
the material consumed, the portion and age of the plant eaten, the
season of the year, the age and size of the animal, and other
factors. In addition, several ornamental plants that are grown
outdoors or indoors are highly toxic. For example, goats should not
have access to, or be fed clippings from yew, azaleas, delphinium,
lily-of-the-valley, and larkspur.
In a pasture situation, goats are “top down” grazers. This behavior
results in uniform grazing and favors a first-grazer-last grazer
system. This might consist of using a goat herd as the first group
and cattle as the last group. This management is most appropriate
with lactating does or growing kids. Goats
naturally seek shelter when it is available. Goats seem less
tolerant of wet cold conditions than seep and cattle because of a
thinner subcutaneous fat layer. A wet goat can easily become sick.
Therefore, it is advisable to provide artificial shelters, such as
open sheds.
Nutrient Requirements
The goat is not able to digest the cell walls of plants as well as
the cow because feed stays in their gastrointestinal tract for a
shorter time period. A distinction as to what is meant by “poor
quality roughage” is necessary in order to make decisions concerning
which animal can best utilize a particular forage. Trees and shrubs,
which represent poor quality roughage sources for cattle, because of
their highly lignified stems and bitter taste, may be adequate in
quality for goats. Goats will avoid eating the stems, but don't mind
the taste and will benefit from the relatively high levels of
protein and cell solubles in the leaves of these plants. On the
other hand, straw, which is of poor quality due to high cell wall
and low protein, can be used by cattle but will not provide
maintenance needs for goats because goats utilize the cell wall even
less than cattle.
Goats must consume a more concentrated diet than cattle because
their digestive tract is smaller relative to their maintenance
energy needs. When the density of high quality forage is low and the
stocking rate is low, goats will still perform well because of their
grazing behavior, even though their nutrient requirements exceed
those of most domesticated ruminant species. Total digestible
nutrients (TDN) and protein requirements are given in Table Two.
Comparing the nutrient requirements to the chemical composition of
feeds shown in Table One should give producers an idea of how to
match needs to appropriate forages. For comparison, low quality
forages have 40 to 55 percent TDN, good quality forages have from 55
to 70 percent TDN, and concentrates have from 70 to 90 percent TDN.
High quality forage and/or browse should be available to does during
the last month of gestation and to lactating does, to
developing/breeding bucks, and to weanlings and yearlings. Female
kids needed for reproduction should be grazed with their mothers
during as much of the milk feeding period as possible and not weaned
early. When the quality of available forage and/or browse is limited
or of low quality, a concentrate supplement may be considered to
maintained desired body condition, depending on the cost benefit.
Whole cottonseed makes an excellent supplement for goats when fed at
no more than 0.5 lb/head/day. Dry does and non-breeding mature bucks
will meet their nutritional requirements of low to medium quality
forage (10 - 12 percent protein and 50 - 60 percent TDN).
Providing free choice a complete goat mineral or a 50:50 mix of
trace mineralized salt and dicalcium phosphate is advisable under
most situations. Selenium is marginal to deficient in all areas of
North Carolina. Therefore, a trace mineral mix containing selenium
should always be provided to the goat herd year round. It is
sometimes advisable to provide a mineral mix that contains 20 - 25
percent magnesium oxide to reduce the risk of grass tetany when
heavy milking goats are grazing lush small grain or grass/legume
pastures early in lactation. Cooper requirements for goats have not
been definitively established. Growing and adult goats are less
susceptible to copper toxicity than sheep, however, but their
tolerance level is not well known. Young nursing kids are generally
more sensitive to copper toxicity than mature goats, and cattle milk
replacers should not be feed to nursing kids. Mineral mixes and
sweet feed should contain copper carbonate or copper sulfate because
these forms of copper are better utilized by the goat than copper
oxide.
The entire article can be viewed at the following URL:
http://www.cals.ncsu.edu/an_sci/extension/animal/meatgoat/pdf_factsheets/ANS%2000%20604MG.pdf
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