Anthelmintic effect of Halothamus somalensis in Arsi-Bale goats

F Dawo and M Tibbo*

Animal Health Research Division, AdamiTulu Agricultural Research Centre, PO Box 35, Zeway, Ethiopia
*Animal Genetic Resources, International Livestock Research Institute, PO Box 5689, Addis Ababa, Ethiopia
dawobf@yahoo.com

Abstract

The root of the medicinal plant Halothamnus somalensis traditionally used to treat endo-parasites of animals and humans was evaluated against endo-parasites in naturally infected goats. The goats were drenched with a crude preparation of the plant at two different doses (0.5 and 2 g/kg live weight [LW]).

The dose of 2g/kg LW reduced faecal egg count (EPG) by 50%.  Packed cell volume (PCV) was also significantly  higher for goats that received 2 g/kg LW. The reduction in faecal EPG and increase in PCV values were negatively correlated. There was no effect on LW change but body condition score was higher for goats that received treatment than goats in the control group.

Future research should focus on evaluation of different extracts from different parts of the plant using laboratory animals and small ruminants

Keywords: endo-parasites control, Ethiopia, goats, Halothamnus somalensis

Introduction

Goats are the second most popular livestock species in the rift valley area of Oromia, Ethiopia (ATRC 1998). They contribute to food self-sufficiency of smallholder farmers by providing food (milk and meat), skin, manure, and direct cash income. In the absence of sufficient feed supplies, proper health care and management the productivity of small ruminants is very low.

Helminthosis is one of the constraints to livestock production in Ethiopia.  It reduces production and reproductive performance of livestock. Smallholder farmers may not easily notice effects of internal parasites on performance of their animals because of the sub-clinical or chronic nature of the diseases they cause (unless the parasite caused death of the animals). Mulugeta et al (1987) working in Ethiopia found that dairy cows treated against sub-clinical parasite infection produced 0.60 kg milk per day more than non-treated cows. In general, economic loss due to sub-clinical infection is much more than that from clinical infections.

Development of parasitic resistance to commercially available drugs has become a serious problem (Mascie-Taylor and Karim 2003) due to misuse of drugs and probably adaptation of the parasites to commercially available drugs. Besides, the drugs are unaffordable, not available or in  inadequate supply under local conditions (Hammond et al 1997); hence future animal production is under severe threat. Historically, most pharmaceutical companies started their business by selling plant extracts (Mez-Mengold 1971, cited in Mathias et al 1996) and a quarter of all prescription drugs currently sold in the Western world still use active ingredients derived from plants (Cox and Balick 1994, cited in Mathias et al 1996). Use of plants as anthelmintics have also been listed in the British Veterinary Codex at least until 1965 (Hammond et al 1997). The potential for new drug development and/or discovery depends on documentation and screening/evaluation of traditionally used medicinal plants. These naturally produced plant drugs, therefore, offer alternatives that can overcome the problems of western drugs (non-availability in developing countries, cost, risk of misuse leading to drug resistance, environmental pollution and food residues) and is both sustainable and environmentally sound (Hammond et al 1997). In a real sense it is economical and also complements the western medicine.

To exploit this huge indigenous knowledge, both basic and applied researches are important. As applied research, evaluation of herbs was carried out by different people against different parasites and/or infectious agents (Adewunmi and Akubue 1981; Ibrahim et al 1983; Akhtar and Ahmad 1992; Hafeel and Shanker 1999; Dawo et al 2001; Alawa et al 2003; Biffa et al 2004). Some of the evaluations led to discovery of effective cure for hepatitis B (a viral disease of human beings) and a Nobel prize (Hafeel and Shanker 1999). Halothamnus somalensis is one of the plants commonly used to alleviate problems of internal parasites in animals and humans in some parts of Ethiopia. This paper, therefore, reports observations on the effect of a crude preparation of Halothamnus somalensis on internal parasites of goats.

Material and Methods

Study area

The study was conducted for three weeks at AdamiTulu Agricultural Research Centre (ATARC) located 167 km South of Addis Ababa, Ethiopia. ATARC is situated in the mid rift valley at 7^º9'N latitude and 38^º7'E longitude. The area has an altitude of 1650 meters above sea level and receives annual rainfall of about 700 millimetres. Natural pasture, the major feed resource of livestock, is composed of predominantly grasses (Pennisetum, Cenchurus, Sporobulus, Aestida and Hyperhenia), legumes (Crotalaria spp.) and acacia tree species.

The plant and processing techniques

The medicinal plant was collected from the South-Eastern part of Ethiopia and submitted to the  National Herbarium, Addis Ababa University for scientific name identification. The scientific name of the medicinal plant is Halothamnus somalensis. The root of Halothamnus somalensis was then purchased from the market. The medicinal plant was ground into powder using a locally made wooden mortar. The powder of the plant was weighed  and administered to the experimental goats on a live weight basis.

Experimental animals and their management

A total of 11 Arsi-Bale goats (FARM-Africa 1996) obtained from ATARC were used. Four goats were randomly allocated to each of the two treatment groups and drenched once with 0.5 or 2 g per kg BW. The powder was mixed with about 150 ml of tap water for ease of administration. Another three goats were left untreated to serve as negative control. All the goats were housed in a shed with a cement floor, fed with hay ad libitum and supplemented with wheat bran. They had free access to water in the afternoons.

Fresh faecal samples were collected into clean bottles. The EPG count was determined by using a McMaster technique (Hansen and Perry 1994) and expressed as EPG of faeces with a lower limit of detection of 50 parasite eggs. Blood samples for PCV determination were collected directly from ear veins into capillary tubes. The body condition (BC) score was recorded using the scale of 1-5 (Suiter 1994). Live weight (LW) was measured using a GHL (UK) weigh scale at the beginning and end of the experiment. All parameters were taken on day 0 (pre-treatment), 7, 14 and 21 (post-treatment). Any clinical signs due to side effects of the medicinal plant  were also recorded.

Statistical Analysis

Percentage reduction in EPG count was calculated using the following formula:

100*(Pre-treatment mean EPG – Post-treatment mean EPG)/ Pre treatment mean EPG

PCV, LW and BC were analysed for fixed effects of treatment, weeks and their interaction. Statistical analysis was done using the General Linear Model procedure of Statistical Analysis Systems (SAS 1994).

Results

The effects of different doses of the medicinal plants on internal parasites of goats is shown in Figure 1. On 21 day after treatment, the 2 g dose had reduced EPG by 50.3%, which was significantly (p<0.001) different from the other two treatments (0.5 g dose and the negative control).

The PCV and BC score at the end of the experiment differed between treatments with highest values for goats that received the  2 g dose and lowest for the negative control. 

There was a negative correlation (r = -0.32, p<0.05) between EPG and PCV. The experimental goats did not show significant (p>0.05) differences in LW but those receiving the plant extract had a higher BC score (P<0.05) than the negative controls.

Discussion

This is the first report on the anthelmintic effect of Halothamnus somalensis on gastrointestinal (endo)- parasites of goats under experimental conditions. The 50% reduction in EPG was similar to the 52% reduction in EPG count reported for the water extract of Albizziz gummifera in Ethiopia (Biffa et al 2004), and very much higher than the 19% reduction in EPG reported for a crude preparation of Azadirachta indica (commonly known as neem tree, Dawo et al 2001).  Alvarez and Nalvarte (1999) reported a 88% reduction in EPG from use of Columnella abovata leaves in sheep, while Akhta and Ahmad (1992) reported 90% reduction in EPG in goats given the fruit of Mallotus philippinensis. The variations in effectiveness of the medicinal plants reported by different authors could be due to many factors, among them the differences in the nature of the plants, soil types where the plants wee grown, methods of preparation, parts used and the initial parasite burden of the animals.

In this study,  the reduction in EPG increased with time after treatment, suggesting that the chemicals responsible for the effect on the parasites might be released slowly.  This increase in the activity of medicinal plants over time corroborates previous reports of such an effect (Hammond et al 1997; Usharani Devi et al 2000; Dawo et al 2001).

The increase in PCV and reduction in EPG  might be due to the temporary depression in egg laying and/or killing of adult worms. The killing of adult worms was not confirmed in this study, as the worm count was not done. The interesting finding in this study is not only the negative correlation between increase in PCV and reduction in EPG but also the observation of improved body condition score in goats that received the 2g dose (Table 1). The non-significant change in LW observed could be due to the short study period. In dairy cows it was reported that LW gain lags behind BC score (Zerbini et al 1996), hence this might be the reason why the change in BC was observed before the change in LW.

The two dosage levels of the medicinal plant appeared to have no adverse effects on the goats and this might suggest that the dose could be increased for future trials.

In drug discovery and development, it is imperative to determine first the sub-lethal dose in laboratory animals and use it as a starting dose for further dose formulation in final hosts infected with the parasites under investigation. The 50% reduction in EPG count observed in the current study was in a simple experiment that did not involve use of extract and/or sub-lethal dose determination in laboratory animals.

Acknowledgements

The authors are grateful to the staff of  the Animal Health Research Division of Adami Tulu Agricultural Research Centre for their assistance in sample collection and laboratory work. The Animal Production Research Division of the centre provided  the experimental goats.

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