Haematology and Plasma Biochemistry of the Wild Adult African Grasscutter (Thryonomis swinderianus, Temminck) M. N. Opara, K. A. Ike, I. C. Okoli
Tropical Animal Health and Production Research, Department of Animal Science and Technology, Federal University of Technology, P. M. B. 1526, Owerri, Nigeria
Abstract: Haematological and plasma biochemical values of the wild grasscutters (Thryonomis swinderianus), were determined. One hundred adult grasscutters consisting of 70 females and 30 males caught in the wild within the months of August to November 2005 were used for this study. Two separate blood samples were collected from each animal, one for haematological and the other for biochemical tests. Results obtained showed no statistical evidence of sexual dimorphism in haematological and biochemical parameters tested. Except for the significantly (P<0.05) higher lymphocytes, eosinophils and basophils values for both the female and male wild grasscutters compared with those of captive reared and significantly (P<0.05) higher white blood cell count in the female wild grasscutters, there were no significant (P>0.05) differences between the values obtained in this study and those reported for the captive reared grasscutters. The haematological and plasma biochemical values observed from the African wild grasscutters were further compared with the data reported in the same environment for humans, wild and domestic mammalian species. [The Journal of American Science. 2006;2(2):17-22].
Keywords: haematology; plasma; biochemistry; grasscutter; Thryonomis swinderianus
It is very evident in Nigeria today that the average citizen does not meet the protein requirements for humans. This is seen from data obtained for alternative sources of animal protein to argument for the shortage currently existing with the conventional livestock (Chupin, 1992).
Wild life domestication has been recognized as a possible way of achieving this objective (Ajayi, 1971).
A few number of small mammals and crop farmers trade or breed wild rodents (Fonweban and Njwe, 1990; N.R.C., 1991), but research studies in their domestication are producing conflicting results (Baptist and Mensah, 1986; N.R.C., 1991).
Among the wild rodents, the grasscutter or cane rat is the most preferred (Asibey and Eyeson, 1997; Clottey, 1981). Grasscutter (Thryonomis swinderianus) is a wild hystricomorph rodent widely distributed in the African subregion and exploited in most areas as a source of animal protein (Asibey, 1974, Vos, 1978 and N. R. C., 1991).
Being the most preferred (Martin, 1985) and expensive meat in West Africa, including Nigeria, Togo, Benin, Ghana and Cote d’ voire (Baptist and Mensah, 1986; Asibey and Addo, 2000), it contributes to both local and export earnings of most West African countries (Asibey, 1969; Baptist and Mensah, 1986; N. R. C., 1991; GEPC, 1995; Ntiamoa, 1998) and is therefore hunted aggressively. Thus, the excessive and uncontrolled decimation of this animal for consumption poses a threat to the ultimate survival of the species.
Grasscutter domestication has not been successful so far, and this has highlighted the paucity of information on the biology, veterinary care, nutritional and management aspects of this rodent under farming conditions.
The physiological, nutritional and pathological conditions of animals are usually assessed, using haematological and biochemical analyses of their blood (Jain, 1986; Bush, 1991; Awah and Nottidge, 1998). Nutrition, age, sex, genetics, reproduction, housing, starvation, environmental factors, stress and transportation are all known to affect haematological biochemical parameters observed between tropical and temperate animals (Ogunrinade et al, 1981; Bush, 1991; Ogunsanmi et al, 1994).
Haematological and biochemical values have been reported in the captive reared grasscutters (Ogunsanmi et al, 2002). There was no sex significance in the values of the male and female grasscutters. However, these authors reported a lower packed cell volume (PCV) in the captive reared grasscutters than African giant rat, but higher than those of pangolin, White Fulani cattle and Nigeria goats, with a similarity to that of man.
Haematological values as well as blood chemistry have not yet been reported for the wild grasscutters. Therefore, there is a need to document these values and compare them with those of the captive reared grasscutters and some other species of animals already reported. This paper presents some haematological and blood biochemical values for adult male and female wild grasscutters in order to establish their normal values and the differences between the sexes and the captive reared ones.
Materials and Methods
2.1 Experimental Animals and Sample Collection
Blood samples were collected from 100 adult grasscutters, 70 females and 30 males between the months of August and November, 2005. The animals were hunted in the wild and caught alive within Ohaji Local Government Area of Imo state. Immediately the animals were caught, their necks were severed through the jugular vein with hunting knives. Then 2 mL of blood was collected from each animal into sample bottles containing ethylene-diamine-tetra-acetic acid (EDTA), another 3 mL into a bottle containing lithium heparin and yet another 3 mL into a tube coated with sodium oxalate fluoride for the determination of haematological, biochemical values and blood glucose level.
The samples collected were immediately taken to the laboratory for analyses.
2.2. Haematology and Plasma Biochemistry
Using the standard techniques as reported by (Jain, 1986), the packed cell volume (PCV), Erythrocyte counts (RBC), Haemoglobin concentration (HB), Mean Corpuscular Volume (MCV), Mean Corpuscular Haemoglobin Concentrtion (MCHC), Total Leucocyte counts (WBC) and Differential Leucocyte counts for the wild grasscutters were determined.
An aliquot 0.2 mL of whole blood in a tube containing lithium heparin was reserved for blood biochemistry, while the other was centrifuged at 2,000 g for 10 minutes to obtain plasma and erythrocytes. The plasma was carefully removed and put into clean tubes, while the buffy coat and the top quarter of erythrocyte layer were removed and discarded.
The remaining layer of erythrocytes was washed twice by centrifugation in phosphate-buffered saline (PBS, pH 7.2). Haemoglobin concentration of these erythrocytes was determined as also previously described (Jain, 1986).
Sodium and potassium concentrations of the whole blood and plasma were measured using the flame photometer (Corning model 400, corning scientific Ltd, England). Plasma levels of chloride, bicarbonate ions, urea, creatinine and total protein were determined as described by Ogunsanmi et al (1994). The activities of plasma glutamic oxaloacetic transaminase (GOT), Glutamin-Pyruvic Transaminase (GPT) were measured by the procedures of Reitman and Frankel (1957). The plasma total cholesterol and blood glucose levels were also determined as earlier described (Toro and Ackermann, 1975).
The erythrocyte and leucocyte values of the male and female wild grasscutters are reported in Table 1. There was no significant difference (P>0.05) in sex for both the haematological and biochemical parameters tested.
Table 2 compared the erythrocyte (RBC) and leucocyte (WBC) values (Mean±SD) in wild and captive reared grasscutters, African giant rat, pangolin, human, cattle, sheep and goat in the same tropical environment (Oduye and Fasanmi, 1971; Oduye, 1976; Ezeilo and Obi, 1983; Oyewale et al, 1997; Oyewale et al, 1998a; Ogunsanmi et al, 2002).
In the wild grasscutters, there were significantly higher (P<0.05) lymphocyte, eosinophil and basophil values for both the females and males compared with those of captive reared grasscutters.
The plasma biochemical values (Mean±SD) in wild grasscutters with respect to their sex are presented in Table 3. The biochemical values for the males were not significantly different (P>0.05) from those of the female wild grasscutters.
A comparison of the plasma biochemical values in wild grasscutters, captive reared grasscutters (Ogunsanmi et al, 2002), Nigerian goats (Oduye and Adedovoh, 1976), White Fulani cattle (Oduye and Fasanmi, 1971), and human (Mcfarlene et al, 1985) are shown in Table 4. There were significantly higher (P<0.05) urea levels in both the wild and captive reared grasscutters than in the African giant rat, pangolin, but the values were significantly lower than in the Nigeria goat and human. Also, the total cholesterol was higher (195.65±5.49) in the wild than captive reared grasscutters, which recorded (126.4±16.05). Equally, the captive reared grasscutters had a higher glucose level (137.6±25.92) than their wild counterparts, which had level of 92.65±9.03. The bicarbonate concentrations were significantly higher (P<0.05) in the wild and captive reared grasscutters and pangolin than in the African giant rat.
The study has shown that both the haematological and plasma biochemical values of the wild grasscutters are very much comparable with those of the captive reared grasscutters as earlier reported (Ogunsanmi et al, 2002). Our result is also in agreement with their findings where they observed no significant difference (P<0.05) in sex in the plasma levels of sodium, potassium, chloride, cholesterol and glucose. As shown in Table 3, slightly higher values of the biochemical parameters for females than the males were observed.
Findings from this study show a higher neutrophil value in the males than in the females as against the case with the captive reared grasscutters (Ogunsanmi et al, 2002). However, there were significantly higher values (P<0.05) obtained in lymphocytes, eosinophils and basophils both for the females than the males. There were also significantly higher (P<0.05) leucocytes (WBCs) for the wild female grasscutters. These could be due to the fact that these animals are in the wild and are prone to all kinds of infections. Leucocyte counts increase during infection and stress of capture (Gotoh et al, 1987; Dinh, 2002) and unfavourable conditions in the animal’s habitat such as shortage of food and water (Gotoh et al, 2001). Basophils and eosinophils are important effector cells in allergy and host defense responses particularly against parasitic infections such as helminthiasis and ectoparasitic tick infestations (Butterworth, 1999). The significantly high levels of basophils and eosinophils may be due to the presence of inhabiting parasites in the wild grasscutters.
Table 1. Some Haematological Values (Mean ± SD) in wild grasscutters with respect to sex
41.7 ± 1.35
RBC (x 106/m)
8.4 ± 0.2
Total WBC (103µl).
Table 2. Comparison of Erythrocyte and Leucocyte values (Mean±SD) in wild and captive grasscutters, African giant rat, Pangolin, Human, Cattle, Sheep and Goat in the same tropical environment.
Wild grasscutter (Present study, n=100)
Captive reared grasscutters (Ogunsanmi et al, n=10)
Table 4. Comparison of some Plasma Biochemical values (Mean±SD) in Wild Grasscutters, Captive reared Grasscutters, African giant rat, Pangolin, Nigreian goat, Cattle and Humans in the same tropical environment
Wild grasscutters (prese-nt study, n=100)
Captive reared grasscutters (Ogunsanmi et al, 2002, n=10)
Total RBC counts were found to be higher in the two types of grasscutters and Nigerian goats than in the other species of animals observed. Packed cell volume (PCV) was found to be lower in the grasscutters than in African giant rat, but higher than those of pangolin, White Fulani cattle, West African Dwarf sheep and goats. It is however similar to that of humans. The haemoglobin concentration of grasscutters was lower than that of humans, but higher than in White Fulani cattle, WAD sheep and goats but similar to those of African giant rats and pangolin. The RBCs of grasscutters were larger (higher MCV) than those of White Fulani cattle, WAD sheep and Nigerian goats; but smaller than in African giant rats, pangolin and humans (Table 2).
There were no significant differences (P>0.05) in sex in the plasma biochemical values obtained in this study. There were also no significant differences (P>0.05) in the values obtained in this study for wild grasscutters and those reported for the captive reared ones (Ogunsanmi et al, 2002 ). However, as shown in Table 4, there were slightly higher cholesterol and lower glucose levels in the wild grasscutters than in the captive reared grasscutters. This could be attributed to the dietary intakes of these free-ranging grasscutters in the wild. No one controls their feeding, unlike in the captive reared animals where the type of diets given is controlled.
It has been reported (Abrams, 1980) that feeds with high level animal fats and oils cause high level serum cholesterol in animals.
Also, there were no significant variations (P>0.05) in the whole blood Na+. and K+..
Among the sexes of wild grasscutters. These observations agree with similar findings in captive reared grasscutters (Ogunsanmi et al, 2002), pangolin (Oyewale et al, 1998b), Nigerian sheep and goats (Oduye and Adedovoh, 1976), White Fulani cattle (Oduye and Fasanmi, 1971; Ogunrinade et al, 1981), Humans (Mcfarlene et al, 1985) and cat (Nottidge et al, 1999). These species of animals have significantly higher (P<0.05) values of sodium than the African giant rat.
There was no significant difference (P>0.05) in the glucose levels of both sexes of wild grasscutters. However, the wild grasscutters had lower glucose level than their captive reared counterparts. There may be excessive utilization of energy reserves by roaming about in the wild free range situations, whereas the captive reared grasscutters being confined, expend comparatively less energy. The total serum protein of the wild grasscutters was significantly higher (P<0.05) than in their captive reared counterparts (Ogunsanmi et al, 2002), African giant rat (Oyewale et al, 1998a), pangolin (Oyewale et al, 1998b) and Nigerian goats (Oduye and Adedovoh, 1976). Their plasma protein levels were however similar to that of White Fulani cattle (Oduye and Fasanmi, 1971).
Our study has presented a baseline data comprising haematological and plasma biochemical parameters of the wild grasscutters. These parameters are very comparable with those of the captive reared grasscutters. It is also clear that sex does not have any significance influence on the parameters investigated in this study.
Variables such as nutrition, reproductive status, environment and degree of activity may change the ex-situ and in-situ situations of grasscutters more especially in the wild. It is therefore concluded that the results of this study can be effectively employed as indices in the evaluation of the dietary quality and clinical status of wild and captive reared grasscutters.
M. N. Opara
Tropical Animal Health and Production Research Laboratory
Department of Animal Science and Technology Federal University of Technology
P. M. B. 1526, Owerri, Nigeria.
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