Materials and methods
Results
Discussion
Bibliography
M. Heinonen, G. Rufe and S. KebedeG. Rufe and S. Kebede can be contacted at the National Artificial Insemination Centre, Ministry of Agriculture, PO Box 62347, Addis Ababa, Ethiopia. Dr Mari Heinonen's present address is: College of Veterinary Medicine, Department of Animal Hygiene, Hämeentie 57, Helsinki 00550, Finland.
The great assistance of the herders who took care of the animals during the collection of the data is gratefully acknowledged. Shola Veterinary Laboratory examined the faecal samples and Dr Katevi Heinonen helped in the statistical analysis.
Ovine fasciolosis in Ethiopia has been studied to some extent (Goll and Scott, 1978; Scott and Goll, 1977), but bovine fasciolosis has not received as much attention. And although cattle do not suffer from acute fasciolosis as much as sheep, the chronic form of the disease is very common. One of the studies carried out on the subject found that about 60 percent of all cattle in Ethiopia were infected with fasciola and half of all calf mortality had been caused by this parasite. This study also reported that untreated animals lose weight because of the parasite (Australian Agricultural Consulting and Management Company, 1985). Fasciolosis is one of the major parasitic diseases contributing to production losses in Ethiopia (Brook, Fesseha and Shibiru, 1985).
In order to provide an artificial insemination (AI) service for remote farms, animals are selected for collection centres near the main roads in some parts of Ethiopia. This usually happens after the long rainy season, when there is enough grass on pastures and when the infection rate of Fasciola hepatica in sheep is at its highest (Goll and Scott, 1978).
The objective of this study was to determine if flukicide treatment benefited the cows collected in the centres in Debre Berhan and if there were any apparent differences between zebu and cross-bred cows. The study followed the effect of antiparasite treatment on the body condition and girth measurement of these animals.
The survey was carried out in two collection centres in Debre Berhan, which is located in the central highlands of Ethiopia at an altitude of approximately 2 900 m. Climatically the area of Debre Berhan is comparable to most of the central highlands in Ethiopia. The heavy rains fall from June to September, with short irregular rainfall in March. The survey pasture contained waterlogged areas, where the cows were very likely to get fluke infection. The owners brought 88 heifers and non-lactating cows to Chacha and 66 to Gennet Giorgis for AI treatment in late October 1989. Altogether 154 cows stayed at the two centres for a period of three to four months. The animals comprised Friesian x zebu crosses (40 percent) and pure zebu (60 percent). The age and parity of the animals could not be defined.
In each centre, one herder took care of the animals. Animals grazed during the day and were put in a barn for the night. No additional feeding was available, but the pasture was good in both centres during the time of the survey.
The authors visited the collection centres three times: the first time immediately after the animals had arrived at the centres in early November 1989, the second time in mid-December 1989 and the third time in late January 1990. During each visit, measurements were taken of the thorax circumference and marks were given for the body condition of each animal. During the first visit, the cows had their ears notched for identification.
Faecal samples were taken from each cow during the first and third visits. These were examined for fasciola eggs by sedimentation at the Shola Veterinary Laboratory, Addis Ababa. The cows were classified as "infected" or "non-infected" accordingly.
During the first and second visits, half of the animals in each centre were treated with the flukicide rafoxanide (RanideR) according to the manufacturer's recommendations (5 mg/kg). (The weight of the animals was estimated.) One bolus (1 g) was given to small cows of about 200 kg (usually zebu) and 1.5 boluses to cows of about 300 kg (usually cross-bred). The animals were selected randomly for the treatment and control groups.
The results were statistically analysed using the chi-square test and the t-test with the computer programs StatgraphicsR and MicrostatR.
Table 1 shows the number of infected cows treated and untreated by breed. There was no difference (p>0.05) in the proportion of infected animals between the breeds during the first visit (before treatment). In the period from the first to the third visit the proportion of infected animals rose significantly (p<0.05), but during the third visit there were fewer infected animals.
Table 2 shows the body condition of the animals during the three visits. All animals improved between the first and the third visit (p<0.05). There was no difference between the treated and untreated animals and no difference between the breeds. Moreover, there was no significant change in the animals' girth (p>0.05).
1 - The proportion of infected cows, treated and untreated, during the first and third visits - Proportion des vaches infectées, traitées et non traitées, au cours des première et troisième visites - Proporción de vacas infestadas, tratadas y no tratadas, durante la primera y la tercera visitas
|
|
Treated infected cows |
Untreated infected cows | ||
|
% |
No. |
% |
No. | |
|
Visit 1 | ||||
|
Zebu |
13a |
5 |
20a |
10 |
|
Cross |
16a |
5 |
12a |
3 |
|
All |
18 |
13 |
17 |
13 |
|
Visit 3 | ||||
|
Zebu |
39b |
14 |
47b |
21 |
|
Cross |
25a |
6 |
44b |
8 |
|
All |
34 |
21 |
46 |
29 |
ab Groups with different superscripts within the same column differ significantly in terms of the variable listed (p<0.05).
2 - Body condition* of the zebu and cross-bred cows during the three visits - Etat général des zébus femelles et des vaches croisées au cours des trois visites - Estado corporal de los cebúes y las vacas mestizas durante las tres visitas
|
|
Zebu |
Cross |
All cows | |||
|
% |
No. |
% |
No. |
% |
No. | |
|
Visit 1 | ||||||
|
Conditions 1-2 |
59 |
53 |
54 |
32 |
57 |
87 |
|
Conditions 3-4 |
41 |
37 |
46 |
27 |
43 |
67 |
|
Visit 2 | ||||||
|
Conditions 1-2 |
47 |
41 |
36 |
21 |
42 |
62 |
|
Conditions 3-4 |
53 |
47 |
64 |
38 |
58 |
86 |
|
Visit 3 | ||||||
|
Conditions 1-2 |
44 |
37 |
33 |
15 |
40 |
53 |
|
Conditions 3-5 |
56 |
48 |
67 |
30 |
60 |
78 |
* Marks given for body condition:
1 = very thin; 2 = thin; 3 = normal; 4 = fat; 5 = very fat.
Fasciolosis is very widespread in Ethiopia. The low-lying areas in the highlands have poor drainage and the soil is acidic, which favours its development (Brook, Fesseha and Shibiru, 1985). Bergeon (1968) found that the rate of infection was 90 percent in Shoa and Gojjam, while Bahru and Ephraim (1979) discovered an infection rate of 63 percent. In the present study, the percentage of infected animals was initially low, only 17 percent, but it later rose to 40 percent. Previous studies carried out in Debre Berhan have indicated October/November as the period of maximum infection of sheep with liver flukes (Jacinta, 1983). Brook, Fesseha and Shibiru (1985) also observed the highest incidence of infection at the same time, four to five months after the start of the heavy rains. Although the animals in the present survey were collected in the centres during this period of maximum infection, the low initial infection rate was possibly the result of the fact that the animals came from several different areas that may not have been as heavily infected.
The control of fasciolosis is based on good pastureland management practices that destroy the intermediate hosts, the snails, which is not always possible. Periodic anthelmintic medication may help to reduce pasture contamination with fluke eggs (Georgi, 1985). In the authors' survey, the only effect the treatment seemed to have had was on the infection rate of cross-bred cows, which could be partly because of the dosage. As the zebu cows were smaller, they were given only one bolus of rafoxanide, which may not have been sufficient. The cross-bred cows were bigger, on the other hand, and most of them were given 1.5 boluses. These dosages were dispensed according to the manufacturer's recommendations (rafoxanide 5 mg/kg). In the literature, however, recommendations for higher doses can be found: Georgi (1985) recommended rafoxanide 7.5 mg/kg for the removal of adult flukes and the medication was found to provide reasonable control of immature liver flukes as well.
The timing of the treatment (early in the dry season) may not have been the best, but it was not possible to treat the animals earlier or later, since they remained at the centre for only a short period. Njau, Scholtens and Kasali (1990) recommended that anthelmintics be given to sheep at the start of the long and short rains.
The condition of the animals improved significantly over the course of the survey because there was plenty of grass all the time and there was no overgrazing. The cross-bred animals managed as well as the zebu cows and the treatment did not affect the condition of either breed. Another study about sheep had similar findings: there was no significant difference in weight gain or loss among 78 male sheep after rafoxanide treatment (Scott et al,, 1974). The weight changes in infected animals were found to depend upon two variables: the fluke burden and the quality of the diet available to the host. For example, animals with approximately 200 flukes that were fed a high-quality ration were able to gain weight throughout the infection and only low protein feeding reversed this trend (Dargie, 1975). Njau, Scholtens and Kasali (1990) reported that nutrition plays a key role in efficient parasite control. stating that the control of helminths without adequate management of host nutrition causes weight loss or morbidity and masks the advantages of the treatment.
In conclusion, the cows did not benefit from the recommended dose of rafoxanide when they were collected in the centres. Whether the treatment would have any benefit under poor, overgrazing conditions or with a higher dosage is unknown.
Australian Agricultural Consulting and Management Company. 1985. Ethiopia, Ministry of Agriculture, project preparation report. National animal health project, main report.
Bahru G. & Ephraim, M. 1979. A preliminary survey of bovine fascioliasis in Ethiopia. Ethiopian J. Agric. Sci., 1(1): 5-12.
Bergeon, P. 1968. Report to the Government of Ethiopia on a veterinary parasitology survey, p. 7. Rome, FAO.
Brook, L., Fesseha, G.-A & Shibiru, T. 1985. Studies on fascioliasis in four selected sites in Ethiopia. Vet. Parasitol., 18(1): 29-37.
Dargie, J.D. 1975. Factors affecting the pathogenesis of fascioliasis in ruminants. Facts and reflections. II. Workshop in fascioliasis held at the parasitological department of the Centraal Diergeneeskundig Instituut at Leiystad from 22-24 May 1975. p. 43-53.
Georgi, J.R. 1985. In Parasitology. for veterinarians, 4th ed. W.B. Saunders Company.
Goll, P.H. & Scott, J.M. 1978. The interrelationship of lymnaea truncatula and ovine fasciolasis in the Ethiopian central highlands. Br. Vet. J., 134: 551-555.
Jacinta, E. 1983. Investigation of fascioliasis in the Ethiopian highlands around Debre Berhan, p. 2-28. Addis Ababa, Ethiopia, International Livestock Centre for Africa (ILCA).
Njau, B.C., Kasali, O.B., Scholtens, R.G. & Akalework, N. 1989. The influence of watering practice on the transmission of fasciola among sheep in the Ethiopian highlands. Ver. Res. Comm., 13: 67-74.
Njau, B.C., Scholtens, R.G. & Kasali, O. 1990. Parasites of sheep at the International Livestock Centre for Africa. Debre Berhan Station, Ethiopia. Prev. Vet. Med., 9: 267-277.
Scott, J.M. & Goll, P.H. 1977. The epidemiology and anthelmintic control of ovine fasciolasis in the Ethiopian central highlands. Br. Vet. J., 133: 273-280.
Scott, J.M., Pegram, R.G., Wubeshet, A., Abege, T. & Turungo, T. 1974. Ethiopian Ministry of Agriculture, Shoa Province veterinary investigation laboratory report on the first year's investigation into sheep diseases on the Debre Berhan Experimental Sheep Station (June 1973 - May 1974).
