Agriculture Reference
In-Depth Information
poor balance of amino acids, whereas fi shmeal and heat-
treated soybean meal provide a desirable mix of amino
acids in ruminally bypassed protein. Protein derived from
ruminants, and poultry litter (potentially contaminated with
ruminant derived protein) must not be fed to goats in the
U.S. even though animal protein sources like blood meal,
or meat and bone meal can be useful sources of high quality
protein. Because these materials may transfer prions (BSE)
and cause human health problems, their use is prohibited
in the U.S. The most common protein sources fed to goats
are the oilseed meals: cottonseed meal and soybean meal.
Urea is a nonprotein-nitrogen source hydrolyzed to
ammonia by rumen microorganisms. Ammonia can be
effi ciently used by microorganisms of the rumen during
fermentation for synthesis of microbial protein, provided
suffi cient energy is available for the microbes to grow.
When used correctly in goat feed, urea can provide an
excellent, cost-effective source of nitrogen. As a thumb
rule, the amount of urea to be fed should be no more
than 25% of the required protein in rations for milking
does. Because urea does not provide energy, it is useful
only when the supply of fermentable carbohydrates is
adequate. This means that its value and usefulness with
low quality forage will be nil unless sources of readily
available energy, such as molasses, are provided. Urea
should not be fed to young ruminants before the rumen is
fully functional. Ammonia toxicity can occur when a large
amount of urea is introduced abruptly into the ration or
intake is excessive due to diet formulation errors or
improper diet mixing. With adaptation to urea, rate of
ammonia production is reduced, so ruminants should be
adapted to diets containing high levels of urea over several
days or weeks.
Commercial protein supplements are available in many
forms: meals, pellets, liquid supplements, and liquid
blocks. Typically protein is the most expensive portion of
the diet purchased off the farm. Therefore, when supple-
menting protein, cost comparisons, the presence of other
dietary components, palatability of the product, ease of
handling, feeding facilities, labor cost/convenience, and
the need for uniform intake should be considered carefully.
Because goats are skilled at sorting feed components being
fed, diets should be formulated and feeding methods
should be employed to reduce or prevent sorting. Sorting
typically is most prevalent when (1) feed components
differ in particle size, (2) components differ in density, and
(3) a surplus of feed is provided. Therefore, protein supple-
ments selected should have a particle size and density
similar to other diet ingredients, and the supply of feed or
time of access to feed should be limited.
Manufactured Feeds and By - Products
Manufactured feeds are mixtures of feeds that often contain
agroindustrial by-products, urea, binders, and preserva-
tives that either are complete diets (providing all the
nutrients required) or supplements (providing nutrients
otherwise defi cient within the basal diet ingredients). The
products used and their proportions in manufactured feed
will differ with cost and availability of by-products at the
local level. Supplements that provide missing nutrients
generally will increase digestibility of low quality forage
and thereby will increase the rate of body weight gain. For
example, olive cake-based feed blocks enriched with
squeezed cactus fruits provide a cost-effective supplement
to a kermes oak-based diet in olive-producing areas of the
world. Such blocks substantially increase the nutritive
value of kermes oak-based diets by partially neutralizing
tannins (Ben Salem et al., 2003). Feed blocks are effi cient
carriers for macro- and micronutrients, tannin-neutralizing
reagents (for example, polyethylene glycol), and anthel-
mintic products for small ruminants. Grain-based com-
mercial supplements may not prove economical for
growing and fi nishing meat goats if not properly formu-
lated for goats. Many high-starch supplements tradition-
ally fed to cattle when fed to goats may reduce ruminal pH
and fi ber digestibility. Typically, diets for growing and
fi nishing goats and sheep contain considerably higher
amounts of roughage than diets fed to cattle.
Certain by-product feeds contain fi ber that is quite
digestible. Such fi ber sources should provide adequate
rates of gain without causing the digestive problems asso-
ciated with high-starch (high-grain) diets. Such feeds
would include soy hulls, corn gluten feed, and wheat mid-
dlings (Moore et al., 2002). Ensiled green tea waste also
has potential as a protein supplement (Kondo et al., 2004).
Dehydrated citrus pulp can replace corn up to 40% in the
diet and can maintain high performance of goats (Bueno
et al., 2002). Mustard seeds contain about 30-35% oil and
34-39% protein. The oil-extracted mustard seed, mustard
cake has a good balance of essential amino acids and a
relatively high methionine content, and it can replace
peanut cake completely with no adverse effect on perfor-
mance (Anil Kumar et al., 2002). Olive leaves traditionally
have been used in Mediterranean countries as a source of
nutrients for small ruminants during periods of scarce feed
supplies. Because olive leaves contain condensed tannins,
they should be supplemented with barley, faba beans
(Yanez et al., 2004), or PEG for optimum utilization.
Condensed tannins will form complexes with dietary pro-
teins, carbohydrates, and microbial enzymes and decrease
protein availability. Good palatability and high-energy
