|Continued harvest of the diverse African Animal Genetic Resources from the wild through domestication as a strategy for sustainable use: A case of the larger Grass cutter: Thryonomys swinderianus||| Print ||
G.A. Mensah1 and A.M. Okeyo2 (Received in 2005)
1. Dr. Ir., Institut National des Recherches Agricoles du Bénin, Centre de Recherche Agricole à vocation nationale basé à Agonkanmey, 0 1 BP 884 Recette Principale, Cotonou, Bénin,
2. International Livestock Research Institute, P.O. Box 30709, Nairobi 00100, Kenya.
Sustainable use of the diverse genetic resources and reduction of its further loss is currently a major concern. Such concerns have increasingly gained more recognition and momentum since the Convention on Biological Diversity that was held in Rio, Brazil, in 1992, and the subsequent follow-up activities (UNEP 1992; Rege 2000; UN 2002).
Genetic diversity, that is, the heritable variation within populations (species, breeds, strains etc.) is usually acted upon by selection, be it natural or artificial. Differential survival of individuals in a particular population in each generation due to selection process ultimately results in changes in gene frequencies, hence evolution of such populations. Genetic diversity (variability) therefore allows for evolution as well as artificial selective breeding to occur.
Animal genetic resources in Sub-Saharan Africa and indeed, elsewhere consist of both the domesticated and wild animal species, all of which are of present and future interests to humankind for economic, scientific and cultural reasons. However, due to various, but mostly human-related activities (Rege 2000), most of these genetic resources are currently threatened with extinction, to varying degrees depending on: 1) the species; 2) endemic region and 3) habitat specificity. The major threat to the survival of wild animal genetic resources arises from the ever-increasing human population and the consequent rise in demand for extra food resources, shelter, recreation space and facilities. This often results in increased encroachment into forest, river valleys and mountains, which were hither to the exclusive critical habitats of the wild animal and plants species. The wild flora and fauna eventually lose their habitats to the expanded modern arable and animal agricultural activities. Besides, increased threats to those wild species that provide food to humans such as the large grasscutter (Thryonomys swinderianus) from direct hunting further add to the extinction threat from increased pressure for food by an increasing human population (Hanotte and Mensah 2002).
The grasscutter1 is the second biggest wild rodent after porcupine in Africa. About 40,000 tons of grasscutter meat per year is consumed in West Africa of which only 0.2% is provided by domesticated grasscutters. Its meat, said to be similarly to that of piglets is greatly appreciated and highly favoured in West and Central Africa (Adjanohoun 1988). It's meat is preferred to the meat of any other kind of domestic animal or commercially available game. The prices of live-weight grasscutter and meat per kg in Benin (3 $US), Cote d'Ivoire (4 $US) and Gabon (9 $US) are 2 to 4 times higher than that of beef, small ruminants or poultry in the three respective countries (Codjia and Heymans 1988; Mensah 1991; Jori et al. 1995). The economic potential of grasscutter meat is high within the region and has an extensive market due to its high demand. However, it is this high demand for grasscutter's meat that currently poses the greatest threat to its very genetic survival, although the species is currently classified as unthreatened according to the FAO's world watch list (FAO 2000). The populations of wild grasscutters in West and Central African countries are declining due to over-hunting and destruction of their habitat. In order to ensure their sustainable existence and use, their domestication at this juncture is therefore most opportune, given the fact that some success in domestication has been achieved in this region (Mensah 1985).
This case study highlights the importance of domestication and adoption of sustainable modern genetic husbandry improvement programs for large grass cutter in Benin and other neighboring West and Central African countries. It also serves to illustrate how harvesting from the diverse pool of wild animal genetic resources through domestication can enhance sustenance of genetic diversity to benefit humankind provided that sustainable breeding programs are adopted.
Results of etho-ecological, behavioral, husbandry and reproductive studies on Thryonomys swinderianus are presented and discussed, some of which would be greatly benefit similar conservation efforts and programs involving the highly endangered wild species such as Kouprey and Banteng of the South East Asia region, if their eminent extinction threats were to be thwarted.
The large grass cutter
Biology and distribution
The grasscutter2 belongs to the mammalian order and family of Rodentia and Tyronomyidae, respectively and is genetically more closely related to the porcupine than to the rat. African, grasscutters are present over a wide range of the continent but are absent or rare over much of South-West Africa, from the Sahara and from the arid Horn of Africa. They are distributed widely throughout Africa's semi-humid regions and are found in many forests and savannas. Grasscutters occur in grassland or in wooded savanna throughout the humid and sub humid areas of Africa south of the Sahara. They do not inhabit rainforest, dry scrub, or desert, but colonize the road borders in forest regions.
They are robust animals measuring up to 60 cm (head and body), weighing more than 9 kg, heavily built, with short stocky legs, a short rat-like tail, clothed with coarse, bristly and even spiny hairs, which look like short soft quills. General coat coloration is speckled brown or buffy above, paler on flanks and greyish or whitish below. They also may have yellow-brown bodies with whitish bellies. The fur is extremely coarse, firm, and bristly- reflecting the animal's kinship to the porcupine. They have thick, heavy claws and enormous orange incisors that can chew through even the toughest vegetation. Nevertheless, they do not bite when handled, although their claws sometimes cause injuries. Although many varieties have been described, they belong to two different species: (1) Smaller grasscutter (Thryonomys gregorianus), (Thomas 1894) which like the name suggests, is smaller in size, may reach 8 kg and a body length of 50 cm and has a shorter tail (Thomas 1922). They are found in savannas in Cameroon, Central African Republic, Zaire, Sudan, Ethiopia, Kenya, Uganda, Tanzania, Malawi, Zambia, Zimbabwe, Mozambique and southward to Rhodesia, and (2) Larger grasscutter (Thryonomys swinderianus) (Temminck 1827) which is of greater size, weighs 9 kg or more and has a head-body length up to 60 cm, a rather long tail and spread from Senegal to South Africa (all countries of west, east, and southern Africa).
Behavior in the wild
Grasscutters are more active during the night and at dawn, as compared to daytime. The grasscutter does not dig holes or burrows, nor does it live in tunnels. Depending on the ambient temperature, they rest either on top of or under a heap of dry grass. When in danger, however, they hide wherever they can find shelter. The grasscutter is an excellent swimmer, has good eyesight, a delicate ear and a sharp scent. It also has a good sense of orientation. Usually, they live in small groups of family colonies, comprising a buck, one or more does and their offspring. Only males live solitarily.
Grasscutters feed on vegetation, and are able to convert the highly cellulotic material into valuable animal protein. This is of particular importance with regard to supply of protein of animal origin for the poor, who may not afford sheep, goat or cattle. The animal meets its mineral requirements by eating soil. (Heymans and Mensah 1984; Mensah 1991).
Behavior in confinement
Grasscutters can be subdivided into 2 categories, the docile and indocile grasscutters. The docile grasscutter adapts well to life in confinement and becomes accustomed to man quickly, whereas the indocile grasscutter panics when people approach and tries to escape from its cage or pen. Grasscutters easily recognize their cage or pen and the individual who takes care of them. The animals communicate with each other and produce different sounds that indicate well-being, warnings as well as submission.
Phases of activity and rest in the animals alternate. Generally, they tend to rest during the hot hours of the day. If environmental temperatures fall below 18oC, grasscutter's activity is also severely decreased.
Irrespective of the kind of forage, grasscutters first eat stalks, the bark of twigs and finally some leaves. This eating habit causes wearing of the animal's teeth, and unfortunately leads to high forage wastage. The grasscutter does practise coprophagy. When it is hot, water intake is reduced, and when the outdoor temperature is low, the animal drinks much more. (Baptist and Mensah, 1986; Holzer 1986; Holzer et al. 1986; Adjanohoun 1988; Mensah et al. 1986; Mensah 2000). The reason for this rather unexpected behaviour is however not yet fully understood, and should be a subjected for further research.
Short history of the development, promotion and description of the captive breeding and improvement programme for grasscutter in West Africa
The need to conserve and maintain the genetic variability of the grasscutter population was initiated in 1983 by the Grasscutter Breeding Promotion Project (PPEAu: Projet Promotion de l'Elevage d'Aulacodes) in Bénin, on realizing the high demand for its meat and hence high intensity with which it was being hunted in the wild. The PPEAu captured wild grasscutters from the natural habitat in Benin during a 3-year campaign (1983-1985). At the same time, partially domesticated animals were purchased from farmers. All the collected grasscutters were kept in confinement, then subjected to a breeding and selection scheme based on 3 levels: (1) the nucleus, (2) the multiplier and (3) the producer (Schrage et al., 1987; Schrage, 1990; Stier et al., 1991). The selection criteria based on the quantitative characters were:
In males, live-weight at the 4th month and the 8th month of age, and docility.In females, live-weight at the 4th month and the 8th month of age, and litter size.
In a series of preliminary studies Schrage (1990), observed that weight for age of the animals was slightly influenced by environment. With regards to docility, which is defined as the reaction of the animal to the presence of humans, it is observed between 4 and 8 months of age in males raised in individual cages, and in females that were raised in groups (Schrage et al. 1987; Schrage 1990; Stier et al. 1991). Young animals (less than 4 months old) tend to be less docile, whereas the older animals (8 months and older) are more docile (Yewadan 2000).
Table 1 shows the heritability estimates of some of the growth traits for the male, while Table 2 gives the same estimates for growth traits and litter size for female grasscutters. These estimates were generally high for growth traits (h2 > 40%), and low for the litter size.
Table 1: Heritability and standard error (in brackets) estimates for growth and fecundity traits in male grasscutters
Source: Yewadan (2000)
Table 2: Heritability and standard error (in brackets) estimates for growth and fecundity traits in the female grasscutters
Source: Yewadan (2000)
Tables 3 and 4 indicate the estimates of phenotypic and genetic correlations between the same traits for males and females. Genetic correlation estimates were found to be high and positive between growth traits. However, very low but favourable (-0.01 and lower) estimates were obtained between growth traits and docility in males, while low (<0.3), but surprisingly favourable (positive) genetic correlations exist between growth traits and litter size in females.
Table 3: Phenotypic (rP) (above diagnonal) and genetic (rG) (below diagonal) correlations between some of the growth traits and docility in male grasscutters.
Source: Yewadan (2000)
Table 4: Phenotypic (rP) (above diagonal) and genetic (rG) (below diagonal) correlations between some of the growth traits and litter size in female grasscutters.
Source: Yewadan (2000)
The selection criteria and breeding programme
During the first five years of the captive breeding and improvement program with wild grasscutters, an evaluation of the zootechnic performances was implemented. Two sub-populations of the successful individuals with regard to these parameters were established from 768 animals. Each sub-population consisted of 17 families, each comprising of couples (16 females, 6 males) ie 272 females and 102 males.
Based on the first three years of operating the selection scheme, a new scheme was developed and applied from 1991 (Stier et al. 1991). This scheme operated in a pyramid structure of 3 levels: the Nucleus, the Multipliers and the Producers. The breeding and selection program being followed is illustrated in Figure 1.
In the nucleus, intense selection is carried out. Although not closed, all male and most of the females replacements are obtained from within the nucleus. A pool 238 females (from within), plus 12 females that annually join as replacements from the lower tiers make a nucleus of 250 females and 102 males. The nucleus supplies some female replacements and all the male parents to the Multipliers.
The multiplier tier has a wider base and is partially accommodated on station (476 females put in reproduction on a cyclic basis). Within this tier, some female replacements are produced from within, and all male and female breeding animals are provided to the producer tier, which is at the base of the pyramid. With this new scheme using imbricated generations, particularly with regards to the males, the reproductive cycle at the nucleus, now varies between 8 and 13 months, compared to 15 months in the earlier scheme.
In 2001 about 800 grasscutter breeding farms existed in Benin (Mensah et al. 2001). Currently, grasscutters are being raised by farmers in a total of 12 African countries: Benin, Burkina-Faso, Cameroon, Congo Democratic Republic, Congo Republic, Cote d'Ivoire, Equatorial Guinea, Gabon, Ghana, Guinea, Nigeria, Senegal and Togo, all of whom obtain their breeding stock through the above scheme. Some wild strains and crosses between the wild and domesticated strains are also kept.
In the absence of genetic parameters, the index of selection had been calculated from weighted averages. Generally speaking, the individuals that were retained (selected) for breeding were those whose performances were superior to the average of the population of interest. But with the availability of the genetic parameters, index method is being adopted, hence allowing for improved selection. Only the best breeders are practicing this method.
After weaning of the young animals at 6 weeks age, they are raised in groups of 8 head per pen for 4 months of pre-selection period. At the end of the pre-selection period, they are selected on the basis of their individual performance and that of their collaterals according to the following index:
I = 17.65 W + 12.35 WB + 35.85 HB; where
I = the index value, W = the live weight at the 4th month of the candidate,
WB = averages of live weight at the 4th month of full brothers of the candidate and
HB = averages of live weight at the 4th month of half brothers of the candidate.
At the end of the pre-selection period, the young males are raised individually in cages and their live weight and docility ratings are taken until they attain 8 months age. At 8 months of age, selection is done on the basis of an index (I) that combines live weight and docility as follow:
I = 0.578(W8 - ECW8) + 16.647 (Doc - ECDoc); where,
W8 = the average live weight (kg) of the candidate at 8 months of age,
ECW8 = the average weight (kg) at 8 months of age of the population from which individuals are to be selected,
Doc = the docility value of the candidate and
ECDoc = the average docility value of the population.
Docility is measured on a scale from 1 to 4. To do this, the animal keeper tries to touch and to stroke the grasscutter and finally assigns the docility values as follows: docility value 1 is assigned if the animal is quiet and accepts strokes; 2, if it moves but without any panic; 3, if the animal is excited and agitated and 4, if it is in complete panic.
The young females are weaned and raised in the same conditions as their male contemporaries. In the 4th month, they are preselected on the basis of the live weight at the 4th month. Final selection of females is based on the litter size of primiparous females or the average of the litter size of two or more consecutive parities for multiparous females.
Trials are currently being conducted to continuously select strains that adapt and produce well under captivity. The nucleus, research or multiplication station in Benin also aims at developing breeding techniques for the production of grasscutter meat at prices that are competitive to poultry meat, the latter being the second most popular meat and to propagate domesticated 93breeds94 or strains for the small farmer in BE9nin and in many other West and Central African countries. Detailed results of several studies that have been carried out on captured wild grasscutter (etho-ecology, behavior, biology, breeding, pathology, husbandry, reproduction, feeding, extension strategy, etc.) are carried out on captivity have been reported elsewhere by Baptist and Mensah (1986) and Mensah (2000).
Results of the 6-year's study form the background for developing grasscutter husbandry in the center of PPEAu. PPEAu undertook extension of grasscutter husbandry in rural areas of BE9nin during the period between 1989 and 1992. From 1993, PPEAu initiated extension services to promote grasscutter husbandry in rural areas of BE9nin. Introduction and further expansion of domesticated grasscutter production in rural areas using imported domesticated 93breeds94 from BE9nin began in 1993, 1994, 1995, 1996, 1997, 1998 and 2000 in Togo, Gabon, CF4te d'Ivoire, Ghana and Nigeria, Equatorial Guinea, Cameroon and Burkina-Faso and SE9nE9gal in that order (Mensah 2000).
The recording and selection programs
The grasscutter breeding program has the following outlined objectives.
1. Ex situ conservation of grasscutter through progressive domestication,
2. Identification of traits of economic importance and development of effective selection and mating schemes,
3. Effective extension strategy of grasscutter husbandry by initiating and strengthening breeder associations and
4. Marketing of improved grasscutter breeding stock strains and meat.
Besides the above, economic, socio-cultural and environmental objectives of grasscutter breeding program include the following:
1. Development of local alternative protein sources through cos-effective grasscutter husbandry in peri-urban and rural area as a complementary income source for the families,
2. Documentation of the indigenous knowledge on and cultural role of grasscutter for incorporation and use in conservation programs and
3. To reduce bush fire and the negative impacts of poachers and hunters.
The basic elements and type of livestock recording-schemes and data processing for the domesticated grasscutter breeding program include: (1) Pedigree and performance recording, (2) Computerized capturing, processing and analyses of records, (3) Feed-back to the farmers with value added information e.g. ranking of individual animals within herd, (4) Regional/national statistics to characterize actual domesticated grasscutter performance and (5) Information sharing and extension service.
Positive market trends and price incentives (increasing demands for, and prices of grasscutter meat), increased awareness by farmers following the 20 years or so of domesticated grassccutter breeding and 10 years of extension program in Bénin and 12 other West and Central African countries, as well as the challenge to increase food production in these countries, has prompted the initiation of a regional husbandry program on domesticated grasscutter breeds in Bénin.
The breeding and selection scheme of domesticated grasscutter is based on and nucleus, multiplier and producer system (see Figure 1) and involves the followings activities:
Reproductive, growth and feed consumption characteristics
A summary of some of the biology and physiological parameters obtained on grasscutter husbandry from various past studies are presented in Table 5.
Pre-pubertal sexual behavior of the male and female grasscutter is accompanied by mounting trials without coital movement. At puberty, this behavior disappears in the young grasscutter doeling. Sexual behavior of the adult female is characterized by 2 consecutive periods, with usually unequal durations. The first period consists of an apparent sexual repose lasting some days to several months. The second period is characterized by a strikingly noisy sexual activity and may last some days up to several months and always comprises 2 consecutive phases (Adjanohoun 1988; 1992): (i) a highly active phase lasts several days and during which the male courts the reluctant and rather frightened female assiduously. This phase may end either by mounting and copulation or in the beginning of a new sexual phase of repose and (ii) a calming down phase from 24 to 48 hours during which the male reposes and evidently shows little interest in the female. On the other hand, the male (buck's) libido is present at all times. However, the male usually shows no interest in the pregnant female until after birth of the offspring.
The newborn suckle their mother and any other nursing grasscutter doe. At maturity, young grasscutter bucks cease to tolerate each other. They fight and can even kill one another. Fights between young dwellings can be observed only when reproduction groups are being formed. Grasscutters have been observed to show cannibalism. Nevertheless, they have no biting reflex and, when caught, surely try to run away, defending themselves by fighting. If the environment changes, noise or a foreign odor is perceived, the grasscutter becomes alarmed and may even panic. However, any animal in panic calms down if it succeeds in hiding its head, even if the rest of the body is visible. (Mensah et al. 1986; Schroder and Mensah 1986; Adjanohoun 1988).
Table 5: Summary of performance characteristics of grasscutter (T. swinderianus)
The nutrient requirement for an adult grasscutter is presented in Table 6. Grasscutters are vegetarian but in captivity are fed with green or dry forages (see Picture 1) and concentrates (see Picture 2). They show a high preference for grass and particularly favor Pennisetum purpureum (elephant grass) and Panicum maximum. They consume nuts, bark, and the soft parts of grasses and shrubs, but also roots and tubers.
Table 6: Nutrient requirement of an adult grasscutter
Source: Mensah (1993; 1995)
Special practical experiences in raising newly captured grasscutter
At first, all animals are put into quarantine stable for at least 3 weeks in cages without floor management. The quarantine stable is dimly lit. Cage keeping quickens the adaptation to confinement and taming process. Reducing the time the personnel stays in the stable and prohibiting any visits by strangers to the grasscutter breeding locations help to minimize stress on the animals.
In order to avoid injuries caused by attempts to escape, the transportation and stable cages must be darkened as far as possible. In the course of 6 weeks at the most, this darkening should be progressively lifted. A cage without protection and litter forces the grasscutter to accept its new environment and to become accustomed to it. A transition period of 8 weeks for feed adaptation should be given. If animals continue to panic, talk softly in a low voice to them or knock gently on the top and side of their cages or pens. If panic continues, it is advisable to leave the stable (Mensah et al. 1992a; 1992b).
When catching grasscutters with your hands, keep the following in mind:
National programs on promotion of grasscutter breeding and a national grasscutter husbandry centers have been successfully established in BE9nin, CF4te d'Ivoire and Gabon, which provide domesticated grasscutter breeding stock to the farmers. To ensure sustainability, several grasscutter breeders associations in these 3 countries have also been formed. The associations organize training of the new farmers on grasscutter husbandry, and help in pedigree and performance recording and marketing of both breeding and slaughter stock. This model can be used for other species that are currently threatened in the wild, but which have potential for being domesticated.
Grasscutter domestication and breeding being a relatively new initiative and undertaking, there are areas that need research attention in order to provide answers to several questions. These include:
1. How to would one best organise grasscutter breeding programme at regional level?
2. Docility is measured only in the male grasscutters, how would one best correct for it and include it in a selection index?
Adjanohoun E. 1988. Contribution au développement de l'élevage de l'aulacode (Thryonomys swinderianus TEMMINCK, 1927) et à l'étude de sa reproduction.. Thèse, Ecole Nationale Vétérinaire d'Alfort, France. N° 111, 198 pp.
Adjanohoun E. 1992. Le cycle sexuel et la reproduction de l'aulacode (Thryonomys swinderianus TEMMINCK, 1927). Mammalia 56:109-119.
Baptist R. and Mensah G.A. 1986. The cane rat. Farm animal of the future. World Animal Review 60:2-6.
Codjia J.T.C. et Heymans J.C. 1988. Problématique liée à l'utilisation du gibier et écoéthologie de quelques rongeurs consommés au Bénin. Revue Nature et Faune 4(4): 4-16.
FAO (Food and Agriculture Organization of the United Nations). 2000. World Watch List for domestic animal diversity. 716pp.
Hanotte O. and Mensah G.A. 2002. Biodiversity and domestication of "non-conventional" species: A worldwide perspective. 7th WCGALP, Montpellier, France.
Heymans J.C. et Mensah G.A. 1984. Sur l'exploitation rationnelle de l'aulacode - Rongeur Thryonymyadae en R.P. Bénin. Données préliminaires. Tropicultura 2:56-59.
Holzer R. 1986. Untersuchungen Zum Verhalten und zur Verdauungsphysiologie der Rohrrate (Thryonomys swinderianus). Mémoire de fin d'études, Université de Hohenheim, 64pp.
Holzer R., Mensah G.A. et Baptist R. 1986. Aspects pratiques en élevage d'aulacodes (Thryonomys swinderianus). III. Comportement de coprophagie. Revue d'élevage et de médecine vétérinaire en pays tropicaux 39:247-252.
Jori F., Mensah G.A. and Adjanohoun E. 1995. Grasscuter production: an example of rational exploitation of wildlife. Biodiversity and conservation 4:257:265.
Mensah G.A. 1985. Rapport final des études préliminaires sur l'élevage des aulacodes au Bénin. Notes techniques sur l'élevage. N° 023, SDS/DEP/MDRAC/Bénin 64 pp.
Mensah G.A. 1991. Elevage des espèces de gibier: cas de l'aulacodiculture (élevage de l'aulacode Thryonomys swinderianus). Actes du Dixième Congrès Forestier Mondial, Paris -1991, Revue Forestière Française, Hors série. Vol. 5:301-309.
Mensah G.A. 1993. Futteraufnahme und Verdaulichkeit beim Grasnager (Thryonomys swinderianus). Thèse de Doctorat, Institut 480, Université de Hohenheim, Allemagne, 107 pp.
Mensah G.A. 1995. Consommation et digestibilité alimentaire chez l'aulacode Thryonomys swinderianus. Tropicultura, 13 (3):123-124.
Mensah G.A. 2000. Présentation générale de l'élevage d'aulacodes, historique et état de la diffusion en Afrique. In Actes Séminaire international sur l'élevage intensif de gibier à but alimentaire à Libreville (Gabon), Projet DGEG/VSF/ADIE/CARPE/UE, pp. 45-59.
Mensah G.A. et Baptist R. 1986. Aspects pratiques en élevage d'aulacodes (Thryonomys swinderianus) I. Modes d'accouplement et durée de la gestation. Revue d'élevage et de médecine vétérinaire en pays tropicaux 39:239-242.
Mensah G.A., Brönnemann A., Stier C.H. et Gall C.F. 1992. Aspects pratiques en élevage d'aulacodes (Thryonomys swinderianus). V. Croissance et usure normales des incisives. Revue d'élevage et de médecine vétérinaire en pays tropicaux 45(2): 175-178.
Mensah G.A., Gnimadi A. et Houngnibo G. 2001. Formulation d'un projet de promotion de la filière aulacode au Bénin - Volume I - Rapport principal : Diagnostic de la filière aulacode au Bénin, 116 p.. - Volume II - Annexes, 113 p.. - Volume II (Bis) - Répertoires des éleveurs d'aulacodes du Bénin au 31/12/2000, 58 p.. - Volume III - Projet de Promotion de la Filière Aulacode au Bénin (PPFAB), CBDD/Bénin 28 pp.
Mensah G.A., Holzer R., Schröder W. et Baptist R. 1986. Aspects pratiques en élevage d'aulacode (Thryonomys swinderianus). II. Détection des chaleurs. Revue d'élevage et de médecine vétérinaire en pays tropicaux 39 :243-246.
Mensah G.A., Schwarzenberg A., Stier C.-H., Kangni T.C. et Gall C.F. 1996. Aspects pratiques en élevage d'aulacodes (Thryonomys swinderianus). VI. Mesures préventives contre la mauvaise usure des incisives. Revue d'élevage et de médecine vétérinaire en pays tropicaux 49 (4):341-346.
Mensah G.A., Stier C.H. et Gall C.F. 1992. Aspects pratiques en élevage d'aulacodes (Thryonomys swinderianus). IV. Premiers essais de tranquillisation per os d'aulacodes indociles. Revue d'élevage et de médecine vétérinaire en pays tropicaux 45(1):37-39.
Rege J.E.O. 2000.
Schrage R., Mensah G.A. and Mack R.P. 1987. Neuere Erfahrungen mit der Haltung von Rohrratten (Grasnagern) in der Volksrepublik Benin. Entwicklung und ländlicher Raum 21(5):7-10.
Schrage R. 1990. Untersuchungen zur Eignung von Thryonomys swinderianus (Grasnager) als landwirtschaftliches Nutztier. Thesis, University of Hohenheim, Germany, 120 pp.
Schroder W. and Mensah G.A. 1986. Reproductive Biology of Thryonomys swinderianus (Temminck 1827). Sonderdruck aus Z. F.: Säugetierkunde Bd, 52, 4.3,5, 164-168.
Stier C.H., Mensah G.A. and Gall C.F. 1991. Elevage d'aulacodes (Thryonomys swinderianus) pour la production de viande. Revue Mondiale de Zootechnie 69:44-49.
Temminck C.I. 1827. Aulacodus swinderianus Temminck 1827, Monographies de mammalogie I, Sierra Leone: 248.
Thomas O. 1894. Description of a new species of reed-rat (aulacodus) from East Africa, with remarks on the milk-dentition of the genus. Annals Magazine of Natatural History. XIII (6):202-204.
Thomas O. 1922. On the aulacodes known as « ground-hogs » or « cane-rats » in Africa. Annals Magagazine of National. History. IX (9): 389-392.
UN (United Nations Organization). 2002.
UNEP (United Nations Environment Programme of the United Nations). 1992.
Yewadan T.L. 2000. Schéma de sélection en élevage d'aulacodes (Thryonomys Swinderianus), Acquis, Perspectives, intérêts de multiplication et des collaborations à ce niveau. In Actes Séminaire international sur l'élevage intensif de gibier à but alimentaire à Libreville (Gabon), Projet DGEG/VSF/ADIE/CARPE/UE.
EMVT-CIRAD. 1992. L'élevage de l'aulacode. Fiches techniques d'élevage tropical. Productions animales. Ministère de la Coopération et du Développement. Maisons Alfort. N° 2, 10 pp.
Jori F. et Noël, J.M. 1996. Guide pratique d'élevage d'aulacodes au Gabon. VSF/Coopération Française. 64 pp.
Mensah G.A. 1991. Manuel d'Aulacodiculture (Elevage d'aulacode) - Edition préliminaire - Cotonou/BÉNIN - 50 pp.
Mensah G.A. 1998. Note technique sur l'aulacodiculture. Projet d'Appui à la Commercialisation et aux Initiatives Locales en Région Centre-Nord, Bouaké, Côte d'Ivoire, 156 pp.
Mensah G.A. et Ekue M.R.M. 2002. Guide technique d'élevage n° 1 sur l'aulacode. Ed B.E.D.I.M., 8pp.
Mensah G.A. et Ekue M.R.M. 2001. Grandes lignes sur l'élevage de l'aulacode en captivité étroite. In: De Visser J., Mensah G.A., Codjia J.T.C. et Bokonon-Ganta A. H. (éditeurs): Guide préliminaire de reconnaissance des rongeurs du Bénin. C.B.D.D./Ecooperation/ReRE/VZZ - République du Bénin/Royaume des Pays-Bas. ISBN: 99919-902-1-6, pp. 228-243.
Schrage R. et Yewadan L.T. 1995. Abrégé d'aulacodiculture. Schriftenreihe der GTZ, N° 251, 103 pp.
Van de Velde M. 1991. Elevage d'aulacodes au Zaïre. Publication du Service Agricole - N° 27, AGCD, Place du champ de Mars, 5, Boîte 57, B 1050 Bruxelles - Belgique - 90 pp.
Appendix 1: French, English and German vocabulary use in grasscutter husbandry
Source: Mensah (1993; 1996)
1 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 (but it is not the true agouti).
2 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 (but it is not the true agouti).
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