In many areas of Africa including Nigeria, goats are produced and managed under extensive management system where they are allowed to move round the village areas feeding on browse plants, domestic wastes, shrubs and grasses (Ewuola 1990). But due to the incessant face–off between crop and goat farmers, intensive management system had been advocated (Larbi et al., 1993).
The
importance of small ruminants in the tropics in general is well recognized (Williamson
and payer 1978). Goats are reared mainly for four functions, namely: meat,
milk, skin and wool, according to order of importance. According to the FAO
(1982) tropical – Africa has about one sixth and about a third of the total world
flock of sheep and goats, respectively.
Goat
production systems throughout the developing countries are divided into there
categories as follows:
1. Extensive
system
2. Systems
using biomass from:
By-produce
of arable cropping
Road
side, communal and arable tethered or grazing systems.
Cut
and carry feeding.
3. Systems integrated with the crops, such
as coconuts or oil palm.
Amongst these,
extensive systems predominate in which goats and sheep are constantly on the
move in search of food.
Management
of Goats
Goat production in Africa is not
developed. The fact that holdings are small seems not to give owners incentives
for improved husbandry practices. In wetter areas, where arable cropping is the
practice, small stocks are tethered during the season in an attempt to prevent
crop damage (Okello and Obwolo, 1985; Adua and Ngere, 1979).
In
Northern Nigeria, Adu and Ngere (1979) described a compound system practiced by
Hausas who are settled and therefore keep their small stock tethered in their compound
and feed them foilage in the rainy season.
Otchere
et al., (1985) reported that goats
are tethered under shelter, while allowing cattle to graze. Similar management
systems have been described by Wilson (1985). The general consensus is that,
after crops have been harvested, small stocks are let loose to feed on crop
residues and fend for themselves.
When
a newly purchased goat is introduced in the farm, it is worthwhile for the
animal to be quarantined for at least a period of 30 days.
Helminithiasis
and ectoparasitosis are widespread in tropical Africa and both seriously affect
the productivity of goats. Helminithiasis which is a serious problem towards
the end of the rainy season and ectoparasitosis which inflicts heavy damage
during the rainy to early dry season, can be controlled by dipping the animal
in solution like gammatex once per week. Vlaenderen (1985) reported that
deworming of adult goat in Togo did not have any effect on weight gain or
mortality. In kids, however, deworming reduced mortality by 50% but growth was
not affected. In ILCA studies in south west Nigeria, Opasina (1984) reported
that ectoparasitic control in goats appeared not to result in higher growth
rates.
In
West African and in Nigeria to be precise, peste, de petit ruminants (PPR) is
endemic. Studies by ILCA scientist in south west Nigeria (Mack, 1982) showed that
dipping with gammatox against ectoparasites and animal vaccination against PPR
very dramatically reduced mortality and increased small stock numbers in
village flocks.
It was observed
that mortality among goats in the ILCA studies decreased by 75%. While death
rate was reduced, off take rate did not increase and therefore flock
inventories rose. Cost benefit analysis demonstrated that animal vaccination
against PPR was viable under south west Nigeria conditions.
An efficient,
well–planned animal health services is a pre-requisite for increasing small
ruminant production in tropical Africa. It must be stressed, however, that any
improvement in animal health services must go hand in hand with an adequate
improvement in the provision of feed.
Nutrient Requirements of Goat
The nutrient requirements
of goats vary according to the size of the animal (age), sex, species and physiological
state of the animal. Weanling goats, lactating does and yearlings require a
high quality diet than adult bucks and dry does.
In order to meet
these needs, does during their last month of gestation and high lactating doe should
be grouped and fed separately from the rest of the herd having lower
nutritional needs. In a grazing situation, animals having the highest requirements
should have access to lush, leafy forage or high quality browse.
Energy
Efficient utilization
of nutrients depends on an adequate supply of energy, which is of paramount importance
in determining the productivity of goats. Energy deficiency retards kid growth
delays puberty, reduces fertility, and depresses milk production (Singh and Sengar,
1987; Sachdeva et al., 1993). With
continued deficiency the animals show a concurrent reduction in resistance to
infectious diseases and parasites. The problem may be further complicated by
deficiencies of protein, minerals and vitamins.
Energy limitations
may result from inadequate feed intake or from the low quality of the diet. Low
energy intake that results from either feed restriction or low diet component digestibility
prevents goats from meeting their requirements and from attaining their genetic
potential. High water content of forages may also become a limiting factor.
Energy
requirements are affected by age, body size, growth, pregnancy, and lactation,
which have been treated as separate items in presenting requirements. Energy requirements
are also affected by the environment, hair growth, muscular activity, and
relationships with other nutrients in the diet which, for best results, need to
be supplied in adequate amounts. Temperature, humidity, sunshine, and wind
velocity may increase or decrease energy needs depending upon the region. Stress
of any kind may increase energy requirements.
Good quality
roughages furnish about 2 Kcal/metabolizable energy (ME) per kg dry matter
(DM). Roughage-concentrate mixed rations are sometimes necessary to increase
the energy content of the diet to 2.5 or 3.0 Kcal ME/Kg DM when feeding early
weaned kids or high producing dairy goats. The efficiency with which energy is
utilized for weight gain, pregnancy, and lactation usually increases with
increasing levels of ME concentration in diet.
It is probable
that under certain condition goats require a minimum of fats in their diets (Fehr
and Delage, 1983; Morand-Fehr and Sauvane, 1989), but more studies are needed
to better define these requirements. Energy requirements for the various
categories of goats have been expressed as digestible energy (DE), ME, and net
energy (NE) for maintenance, gain, pregnancy, lactation, and fiber production.
Protein
Proteins are the
principal constituents of the animal body and are continuously needed in the
feed for cell repair and synthetic processes. The transformation of feed
protein into body protein is an important process of nutrition and metabolism.
Proteins consist of amino acids and are the building blocks of all body cells.
Secretions such as enzymes, hormones, mucin, and milk have additional amino
acid requirements. Proteins are, therefore, vital for animal maintenance, growth,
reproduction, and milk production. However, non protein nitrogen (NPN) can
substitute for parts of the required protein for these functions (Harmeyer and
Martens, 1980).
Protein deficiencies in the diet deplete
stores in the blood, liver and muscles, and predispose animals to a variety of
serious and even fatal ailments. Below a minimum level of 6 percent crude
protein (CP) in the diet, feed intake will be reduced, which leads to a
combined deficiency of energy and protein (Perkins, 1983; Platt et al., 1986). This deficiency further
reduces rumen function and lowers the efficiency of feed utilization. Long-term
protein deficiencies retard fetal development, lead to low birth weights, affect
kid growth, and depress milk production (Singh and Sengar, 1987).
Protein
requirements have been presented in terms of total protein (TP) and digestible protein
(DP). The former has been recommended as the most accurate guide for converting
proteins from feed composition tables to quantities required (Broster, 1992,
Preston, 1992; Satter and Roffler, 1995), but DP values are also used widely
around the world.
Protein
requirement for maintenance have been reported: 2.66g (Haenlein, 1980); 2.50g
(Majumdar, 1985b); 2.85% (Singh and Sengar 1987): 3.19g (Winter and Goersch, 1987);
2.12g (Itoh et al.,1990);3.05g (Rajpoot, 1992) and 3.40g (Sengar, 1993); the
mean value is 2.82g DP or 4.15g TP / Wkg0.75, with an average digestibility
of 68 percent for total protein. This compares closely with 4.73g TP (NRC, 1995)
for sheep and 7.09g TP/Wkg 0.75 (NRC 1998) for dairy cattle.
Except for the
minimum maintenance requirements for protein, no other biologically determined values
for body functions exist. The requirements of protein for weight gains have
been derived from following values, 6.274 (Devendra, 1999b) and 0.139
(Akinsoyinu 2000) the mean is 0.195g DP or 0.284g TP/g gain.
Minerals
Requirements of
minerals have not been established definitively for goats at either maintenance
or production levels. However, some classical studies in mineral metabolism have
been conducted with goats as experimental subjects. Hart et al., (1982) and Henderson and McGee (1984) reported data on
calcium metabolism in goats, which led to the discovery of the role of vitamin
D in calcium absorption and metabolism. Lintzel and Radeff (1993) reported important
work on iron nutrition in goats. In general, these and more recent studies support
assumptions that some mineral requirements in goat are similar to those in
other ruminant species; therefore, mineral requirement rely for the time being
on values recommend for sheep (NRC, 1995) and dairy cattle (NRC, 1998). The literature
on mineral nutrition in goats was recently reviewed.
In addition to
the elements in organic matter (oxygen, nitrogen, carbon, and hydrogen), seven
major and nine minor minerals are considered dietary essentials for livestock.
The major minerals that must be fed in relatively large amounts are calcium,
phosphorus, sodium, chlorine, magnesium, potassium, and sulfur. Minor or trace
minerals, required in small amounts, include iron, iodine, copper, molybdenum, zinc,
manganese, cobalt, selenium, and fluorine. Others which are possibly essential at
extremely low levels are chromium, nickel, vanadium, silicon, tin and arsenic.
Most of these essential or possibly essential elements occur naturally in
feedstuffs at levels that do not constitute problems in nutrition. However,
situations often exist when one or more minerals, especially the major ones,
are sufficiently low to reduce productivity. Trace minerals in particular can
be present in toxic amounts. Proper balance of minerals and bio-availability
from supplements are often more important than actual levels (Miller 2004).
VITAMINS
They are needed in small
quantities by the body. The most likely deficient vitamins in the diet are
vitamin A and D. Vitamins B and K are
formed by the rumen bacteria of goats. Vitamin C is synthesized in the body
tissue in adequate quantity to meet the need of the animals. Vitamin A is not
contained in forage but carotene found in green leafy forage is converted to
vitamin A and stored in the liver and fat of the goats when the intake exceeds
normal.
Goats
consuming weathered forage or forage that have undergone long term storage
should be fed a mineral mix containing vitamin A or should receive vitamin A
injection. Vitamin D may become deficient in animals raised in confinement
barns. Animals should have frequent access to sunlight because it causes
vitamin D to be synthesized under the skin of goats.
Good
quality sun cured hays are excellent sources of vitamin D. Deficiency of
vitamin D results to poor calcium absorption leading to rickets, a condition
where the bones of young animals and joints grow abnormally.