Agriculture Reference
In-Depth Information
INTRODUCTION
The single greatest cost in any livestock enterprise is the
cost of supplying feeding. With intensive feeding systems,
feed cost averages 64% of the variable cost of an operation
(excluding labor) or some 45% of the variable cost of an
operation including labor. Management practices that
reduce the cost of feed and feeding will improve profi t-
ability of a livestock enterprise. The major points in the
feeding management of goats will be discussed to help
readers understand differences among feeds and feeding
practices that are humane, promote good health, and
encourage strong immune function of goats with emphasis
on effi cient and economical production of meat, milk, and
fi ber.
fi ber (ADF), cellulose plus lignin, usually is proportional
to digestibility of a feed because lignin is indigestible and
cellulose is fermented slowly. A general scheme outlining
chemical composition for typical feedstuffs is illustrated
in Figure 10.1 .
Feeds for goats can be divided into two groups: forage/
roughage and concentrates. The ideal proportion of forage
to concentrate in the diet depends on an animal's physio-
logical stage and the desired level of performance. Goats
managed for milk production have higher nutritional
requirements and usually are fed higher amounts of
grain to maintain milk production for 9-10 months when
compared to goats managed for meat production (only
3-4 months of milk production for the kids).
Goats consume a wider spectrum of plants than other
ruminants. As selective browsers, this grazing behavior
facilitates the ability of goats to survive under harsher,
semiarid conditions than either sheep or cattle. Goats
selectively consume and digest a wide variety of shrubs,
woody plants, weeds, and briers.
FEEDS
Specifi c feeds are not required. Instead, the nutrients from
feeds, for example, protein, energy, minerals, and vita-
mins, are required and must be provided by feed ingredi-
ents provided in the diet. Feed ingredients include those
provided by humans as well as feed components gleaned
by animals from available forage or browse. First, protein
is needed. Protein may come partly from nonprotein nitro-
gen sources like urea. Next, energy is required; that
typically is obtained from dietary carbohydrates (sugars,
starches, and fi ber), fats, and to a lesser degree, excess
protein. Accurate feed management is a three-step process.
First, nutrient requirements of the animal must be esti-
mated; second, the composition of available feeds must be
assessed; and third, one seeks to provide appropriate
amounts of nutrients from specifi c feeds to meet the nutri-
ent requirements. Nutrient requirements of goats for main-
tenance, growth, pregnancy, and production of meat, milk,
and fi ber are published in the NRC (2007). For practical
purposes, selected nutrient requirement tables are provided
in Appendix B .
Feed analysis is usually based on chemical analysis of
a representative sample of forage, supplements, or concen-
trate feeds. Preferably, feeds should be analyzed individu-
ally. Feed analysis laboratories use specifi c chemical
procedures to assay feeds. Typical measurements include
dry matter (100 minus moisture), nitrogen, ether extract,
and ash, all of which are determined by “proximate analy-
sis.” The carbohydrate portion of feeds often is assayed by
detergent fi ber analysis (Van Soest et al., 1991) where cell
contents are separated from cell wall constituents. Cell
wall constituents, also called neutral detergent fi ber (NDF),
include cellulose, hemicellulose, and lignin. Because of
their bulkiness and slow rate of digestion, feed intake will
be reduced when diets rich in NDF are fed. Acid detergent
Forage/Roughage
Forage/roughage generally is rich in fi ber (18% crude fi ber
or more) and low in energy, adds bulk to the goat's diet
and thus enhances passage, and increases the butterfat
content of the goat 's milk. Most forage/roughage consists
of the green vegetative parts of the plants though some are
by-products (straw, hulls). Forage feeding often is eco-
nomical and in such cases should be maximized in practi-
cal goat-feeding operations. Forage/roughage includes
both wet forage/roughage (pastures, green chop, trees,
shrubs, and silages) and dry forage/roughage (hay, pelleted
forage, and some by - products).
Fresh forage may be grazed or fed to goats in stalls in
a zero grazing system. Goats consume large amounts of
forage when grazing, but intake may be even greater when
fed forage in a cut-and-carry feeding system. Goats select
long hay over chopped hay and leaves over stem portions
of forage. Fresh forage often is preferred, followed
next by hay, and fi nally by silages. When goats graze
pasture or browse, they typically choose a higher quality
diet than that offered in the trough. When given a choice,
per unit body weight (BW), goats consume more legumes
than grasses, more alfalfa than clover, and more Italian
ryegrass or corn and sorghum than orchardgrass and
fescue. Within each plant species, voluntary intake will
vary with stage of plant growth. Intake is maximum 1-2
weeks before grain production with grasses and 1 week
before budding with legumes. The relationship between
the nutritive value of forage and its voluntary intake is well
