Items in cart [0]
| [ Top of Page ] [ Home ] [ Contact Us ] [ Help ] [ The National Academies Home ] | ||
Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 233
19
Grasscutter
The grasscutter~ (Thryonomys swinderianus and
Thryonomys gregorianus) is found in many forests and
savannas of Africa. Its meat, said to resemble suckling
pig, often sells for more per kilogram than chicken,
beef, pork, or lamb. It is the preferred, and perhaps
most expensive, meat in West Africa. Indeed, in Ivory
Coast it sells for about $9 per kg. With prices like that, grasscutter is
a culinary luxury that only the wealthy can afford.
If domestication of this wild species were successful in providing
meat at a price similar to that of poultry (the second most popular
meat), markets would be unlimited.2 However, as production costs
are high, long-term research will be required before grasscutter pro-
duction can be profitable to the small farmer. This research should
now be undertaken.
In an effort to capitalize on the markets for this delicacy, agricultural
extension services of Cameroon, Ghana, Ivory Coast, Nigeria, Togo,
and particularly Benin are already encouraging farmers to rear grass-
cutters as backyard livestock. They furnish breeding stock and infor-
mation, and maintain central offices for records. In addition, a bilateral
cooperation project in Benin has started experimental work on im-
proved breeding methods combined with the study of animal responses
under domestication.3
In future, this vegetarian animal might become the African equivalent
of South America's guinea pig, playing an important role in reducing
Africa's chronic protein shortage.
' Also referred to as the cutting-grass or cane rat; in French-speaking African countries,
the grasscutter is referred to as agouti, which simply means an animal from the bush.
It is not the true agouti (see page 198).
2 Baptist and Mensah, 1986.
3 Baptist and Mensah, 1986.
233
OCR for page 234
MICROLIVESTOCK
Natal, South Afnca. This young grasscutter, only a few months old, already weighs
1 kg. The rounded nose and ears, the spiny fur on the back, and the very shalt tail all
distinguish it from true rats. The handlike forepaws are adept at holding and manipulating
grass stalks. (A.J. Alexander)
AREA OF POTENTIAL USE
Humid and subhumid Africa south of the Sahara.
APPEARANCE AND SIZE
Grasscutters are robust animals with short tails, small ears, and
stocky bodies. Taxonomically, they are more closely related to por-
cupines than to common rats or mice.
Although many varieties have been described, there are probably
only two species. The larger (Thryonomys swinderianus) weighs 9 kg
or more and has a head-and-body length of up to 60 cm. The smaller
species (Thryonomys gregorianus) may occasionally reach 8 kg and a
body length of 50 cm.
Both species have yellow-brown to gray-brown bodies, with whitish
bellies. The fur is extremely coarse, firm, and bristly reflecting the
animal's kinship to the porcupine. The tail is scaly and has short,
sparse hairs.
OCR for page 235
GRAS S C UTTER
235
Both species have thick, heavy claws and enormous orange incisors
that can chew through even the toughest vegetation. (Grasscutters
have been known to tear holes in corrugated iron fences.) Nevertheless,
they do not bite when handled, although their claws sometimes cause
. . · A
nJurles.~
DISTRIBUTION
Grasscutters occur in grassland or in wooded savanna throughout
the humid and subhumid areas of Africa south of the Sahara. They
often live in forest-savanna habitats where grass is present. They do
not inhabit rainforest, dry scrub, or desert, but they have colonized
the road borders in forest regions. Distribution is determined by
availability of adequate or preferred grass species for food. Specifically,
Thryonomys swinderianus occurs in virtually all countries of west,
east, and southern Africa. Thryonomys gregorianus occurs in savannas
in Cameroon, Central African Republic, Zaire, Sudan, Ethiopia, Kenya,
Uganda, Tanzania, Malawi, Zambia, Zimbabwe, and Mozambique.
STATUS
Despite heavy hunting, these animals are not threatened with
extinction. Nonetheless, many individual populations are well below
carrying capacity, or are extinct because of local overexploitation.
HABITAT AND ENVIRONMENT
The larger grasscutter (T. swinderianus) generally lives in swampy,
low-lying areas, especially along river banks and the borders of lakes
and streams. Occasionally, it is found on higher ground among bushes
and rocks, living where savanna grasses are dense and tangled enough
to afford good cover. In Ivory Coast and southern Guinea, for instance,
grasscutters are found (and hunted) throughout the savanna zones.
And they can occur in close proximity to farmlands and people (for
example, in southwest Nigeria).
BIOLOGY
Although the precise diet in the wild has not been determined,
4 Information from W. Schroder and S. von Korn.
OCR for page 236
236
MICROLIVESTOCK
Thryonomys swinderianus \_,
Thryonomys gregorianus
o
Grasscutters occur across tropical Africa and through the grasslands of East Africa, as
far south as the eastern Cape. Throughout this region, where other meat is often
expensive and scarce, a grasscutter makes a welcome meal.
grasscutters are vegetarian. They consume nuts, bark, and the soft
parts of grasses and shrubs. They particularly favor elephant grass
and sweet potatoes. They commonly "raid" cassava and yam plan-
tations, and are considered local pests.
Grasscutters reproduce year-round, although the births seem to peak
at certain times of the year, correlated with weather conditions.5
Probably one male takes several females, and the family group possibly
has more than one generation of young. The gestation is about 152
days. Apparently, litters normally contain between 2 and 4 young, but
in Benin and Togo some litters of up to 11 or 12 are reported.6
Newborns are fully developed, their eyes are open, they weigh
approximately 80 g, have thick fur, and quickly become accomplished
runners.
BEHAVIOR
Although they commonly forage in groups, grasscutters are generally
solitary. They are nocturnal, and they travel at night through trails in
s Information from W. Schroder and S. von Korn.
6 Information from G. Mensah and from W. Schroder and S. von Korn.
OCR for page 237
GRASSCUTTER
237
reeds and grass, often to water. Most specimens seen in markets are
males, possibly because males lead the groups and are thus most prone
to being trapped.
When alarmed, these animals stamp their hind feet and give a strange
booming grunt. When fleeing, they can run very fast and, given a
chance, will take to water. They swim with ease.
For shelter, grasscutters usually weave nests of matted vegetation
or scoop out shallow burrows.
USES
In a broad geographic band across sub-Saharan Africa, cattle raising
is severely limited by trypanosomiasis. There, other sources of animal
protein, including rodents, are traditionally used. Thus, grasscutter
meat constitutes an important food for many Africans. The animals
are mostly caught and eaten by families for their own use, but some
are sold in markets and especially in roadside stalls. Many families
depend exclusively on selling bushmeat, particularly that of grasscut-
ters. In Accra, Ghana, during one year, 73 tons of grasscutter meat
were sold in the local market. This represented more than 15,000
animals. In southern Africa, too, people find that these rodents make
tasty food, although they may cut off the tail to make the carcass look
less catlike.
The meat is usually eaten smoked, and is so much in demand that
grasscutters are hunted in organized drives with spears, dogs, and
sometimes fire. It is considered excellent, especially when cooked in
soups and stews or barbecued.7 It has been described as resembling
venison in flavor, but it is dark like the meat of wild duck.
HUSBANDRY
In the savanna area of West Africa, people have traditionally captured
wild grasscutters and raised them at home. As an extension of this,
organized grasscutter husbandry has been initiated in West Africa.
The animals are provided with marshy, tightly fenced areas with plenty
of plant cover. The young are harvested from these areas and raised
separately.
Ghanaian researcher Emanuel Asibey, a pioneer of this research,
reports success at getting such captive stocks to reproduce. To this
end, farmers are provided with breeding boxes and foundation grass
7 Information from E.S. Ayensu.
OCR for page 238
238
MICRO LIVE STOC K
cutter colonies. They are taught how to rear and feed the animals for
home consumption or for cash income. Basically, the farmers make
available large sheds where the animals can move freely. To prevent
escape, the walls may be reinforced with cement plaster. The farmers
also provide piles of grass, sugarcane, and other foods. A grasscutter
reportedly takes about a month to adjust to such confinement. High
mortality can occur in this period. The average weight of a mature,
home-raised grasscutter is =7 kg. The average killing-out (dressed
carcass) is 64 percent.8
The Wildlife Domestication Unit of Ibadan University in Nigeria,
another pioneer of rodent domestication, has also reported the potential
of domesticated grasscutter colonies.9
Research on grasscutter breeding, husbandry, and feeding is similarly
being implemented by the Ministry for Rural Development in Benin
and at the Lacena in Ivory Coast (see Research Contacts).
ADVANTAGES
The demand for grasscutter meat is so large that it is not being met.
Markets for it already exist over much of Africa.
LIMITATIONS
Grasscutters can devastate such crops as rice, sugarcane, soybeans,
peanuts, yams, cassava, sweet potatoes, oil-palm seedlings, maize,
young rubber, sorghum, and wheat. Therefore, as with most rodents,
they should be reared only in areas where they already exist.
In past years, captive animals in Benin have suffered fatal Clostridium
infections during September and October. In 1986, a broad-spectrum
antibiotic was given with outstanding results. During this season, the
animals also suffered from ascarid worms, which were also successfully
treated with standard drugs.~°
RESEARCH AND CONSERVATION NEEDS
Research is needed in the following areas:
· Digestive physiology, feeding habits, feed preferences, feed con-
version and growth rate;
~ Information from E.O.A. Asibey.
9 Tewe, Ajayi, and Faturoti, 1984.
'I Information from W. Schroder and S. von Korn.
OCR for page 239
GRASSCUTTER
239
· Diseases (pathogens and parasites);
· Captive breeding and management (growth rates, space require-
ments, feed needs, etc);
· Performance under different environments;
· Productivity; and
· Basic biology (for example, chromosome type, reproductive phys-
iology, and social behavior both in its wild state and under controlled
conditions).
Moreover, specimens should be gathered from different regions for
comparative evaluation. A particular need is to select and breed docile
specimens because today, even after several generations in captivity,
the animal must still be handled with caution.
Although domestication of the grasscutter is encouraged, wild
populations might also be managed to maximize and sustain production
through habitat manipulation.
OCR for page 240
I: - ~:
'r ,'V'~4
~ ,~P;~. ''`;
,.~,~g
·
:
.... . ....
,: ~
. .',.' ~*4
..
.,.
,.
Of
.,
., ;.
:,,
: a'
i
i,,.'
.:"~"-'
Representative terms from entire chapter:
von korn