The efficacy of different dose levels of albendazole for reducing faecal worm egg count in naturally infected captive grasscutters, Thryonomys swinderianus, Temminck

E K Adu, H R Otsyina and A D Agyei

Animal Research Institute, CSIR, P. O. Box AH 20, Achimota, Ghana
ari@africaonline.com.gh   /   nhyirapapa@yahoo.com

Abstract

The efficacy of different dose levels of albendazole for reducing faecal worm egg count in naturally infected captive grasscutters was investigated in an in-door trial using twenty weaned grasscutters weighing between 325 g and 925 g at the Animal Research Institute, Achimota, Ghana in a completely randomised block design from 20 September 2004 to 10 November 2004. The drug was administered after impregnation into cane sugar pieces at three dose levels: A (0 mg/kg BW) B (2.5 mg/kg BW, i.e. ½ the manufacturer's recommendation) C (5.0 mg/kg BW, i.e. the manufacturer's recommendation) and D (7.5 mg/kg BW, i.e. 1½ the manufacturer's recommendation) using the recommendation for small ruminants. The efficacy of the drug for reducing the faecal egg count was determined using the percentage faecal egg count reduction (FECR%) technique.

 

The most important finding in this study was that albendazole is efficacious for reducing faecal egg count in captive grasscutters at a dose level of 2.5 mg/kg BW. Though there was no significant difference in the live weight gains of treated animals compared to animals in the control group, growth rates in all treated animals tended to decline. This is speculated to be due to a possible toxicosis of albendazole in the grasscutter. The ease with which the animals accepted the cane sugar pieces when impregnated with albendazole also indicates that the drug can easily be administered with little technical supervision.

Key words: albendazole, cane sugar pieces, faecal egg count reduction percentage, grasscutter, Thryonomys swinderianus

 

Introduction

 

Grasscutter or greater cane rat (Thryonomys swinderianus, Temminck) farming is a budding smallholder venture in West Africa (Baptist and Mensah 1986; Kyle 1987; Adu et al 1999) where the meat is considered a delicacy (National Research Council 1991). Grasscutter meat is also the most popular meat in South Africa (Van Zyl et al 1999). The current trend in grasscutter farming is towards increased stock levels and intensification of production practices. Accompanying the intensification of livestock management practices is increased incidence of diseases. However grasscutters are usually farmed with little or no medication though Mpoame (1994) in Cameroon reported several helminth parasites in wild grasscutters. The health of captive grasscutters can thus no longer be taken for granted.

 

A major parasitic condition of livestock under intensive management with significant economic consequences is helminthosis (Sykes 1994). The devastating effect of helminthosis in grasscutter farming was brought to the fore with an outbreak of unexplained deaths in farms at Awoshie, a peri-urban centre of Accra, Ghana, with one farm recording over hundred deaths within one month. Post mortem results revealed heavy infection with worms. Although no report exists for the grasscutter, albendazole, a broad spectrum anthelmintic of the benzimidazole group, has been widely used for other livestock in reducing faecal egg counts (Blanton et al 1998; Madzingira et al 2002; Peniche et al 2002; Seno et al 2002). This paper reports the efficacy of different dose levels of albendazole for reducing faecal worm egg count in naturally infected captive grasscutters.

 

Materials and methods

 

Albendazole, 2.5% (Mobedco-Vet, Jordan) was administered to twenty weaned grasscutters weighing between 325 g and 925 g from 20 September 2004 to 10 November 2004. The animals were weighed and assigned to one of four treatments in a CRBD as in Table 1 based on the manufacturer's recommendation. They were then weighed weekly. The animals were housed in single cages measuring 41.5 cm x 29.5 cm x 16.5 cm with trays to collect the faeces. Grasscutters have a very high preference for cane sugar; the drug was thus impregnated into pieces of cane sugar and presented to the animals before feeding. They were fed freshly cut Panicum maximum ad lib twice daily without water following the practice of grasscutter farmers in Ghana (Adu et al 1999).

 

Faecal samples were taken at about 9.00 am each morning, labelled with the identification of the animal and taken to the laboratory for the determination of faecal egg count using the modified McMaster method (Ministry of Agriculture Fisheries and Food 1977). The parameters analysed were liveweight gains (LWT), and faecal egg count (FEC). Sex was used as a covariate for the analysis of liveweight gain since growth rate in males differed from females (Schrage and Yewadan 1999). Because of a skewed distribution, FEC was analysed using a logarithmic transformation (LFEC, log₁₀ (FEC+25)). The results were back-transformed by taking antilogarithms and presented as geometric means (GFEC). All statistical tests for FEC were applied to the transformed data. LWT and LFEC were analysed in an ANOVA following the GLM procedure of SPSS for Windows (version 10.0).

 

The faecal egg count reduction percentage (FECR%) was calculated as:

 

FECR (%) = 1 - (T₂*C₁)/(T₁*C₂)*100

 

where T₁ and T₂ are the GFECs of treated animals at the beginning and end of each period, and C₁ and C₂ are the GFECs of the control group for the corresponding period.

 

Results and Discussion

 

There was no significant difference in the live weight gains of treated animals compared to animals in the control group. This may be due to low parasitic burden in the animals used for this study (Table 1).

However, there was a tendency for live weight gains in all the treated animals to decline compared to untreated animals with the decline reflecting the geometric faecal egg counts at the beginning of the study (Table 1). Though albendazole has wide application across animal species (Blanton et al 1998; Madzingira et al 2002; Peniche et al 2002; Seno et al 2002) birds of the order Columbiformes are susceptible to toxicosis, exhibiting marked leukopenia, bone marrow hypoplasia and crypt epithelial changes in the small intestines after treatment (Howard et al 2002). Toxicity to albendazole was not investigated in this study. It was therefore not possible to determine the toxic effect of albendazole in grasscutters.

 

The percentage faecal egg count reduction for all treatments the first three days post treatment was less than 95% and showed no significant differences. This however improved for all treatments after 3 days post treatment. The pattern of faecal egg count reduction for Treatment C (7.5 mg/kg BW) was erratic compared to the other treatment groups (Figure 1).

 

 Two animals, one each from Treatments A and D died during the study. Post mortem results attributed the deaths to traumatization as a result of mishandling. The fact that none of the animals died as a result of the treatment indicates that albendazole may be safe for grasscutters. However the effect of the drug on productivity (i.e. live weight gains) needs further investigation. The ease with which the animals accepted the cane sugar pieces when impregnated with albendazole also indicates that the drug can easily be administered with little technical supervision. It may however be advisable to weigh the animal to determine the right dosage for a particular animal.

 

Conclusions

• The most important finding in this study is that albendazole is efficacious for reducing faecal worm egg count in captive grasscutters at a dose level of 2.5 mg/kg BW.

Acknowledgements

 

Farmers of the Grasscutter Cooperative Farmers Society - Pokoase and Awoshie Branches, particularly Mr Teye Ocansey, are acknowledged for donating the animals for this work. Masseurs Julius Beyou, Humphrey Amafu-Dey and Abraham Oko Teye are acknowledged for technical assistance in the faecal egg count. Mr Anthony Mensah is also acknowledged for feeding and cleaning the animals during the study.

 

References

 

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