COMPARISON OF TRYPANOSOMOSE INFECTION BETWEEN NKEDI ZEBU CATTLE AND ANKOLE CATTLE UNDER HIGH TSETSE CHALLENGE IN UGANDA 

COMPARAISON DE L’INFECTION TRYPANOSOMIENNE ENTRE LE BOVIN ZEBU NKEDI ET LE BOVIN ANKOLE DANS DES CONDITIONS DE FORTE PRESSION GLOSSINAIRE EN OUGANDA

J. W. Magona¹, J. Walubengo¹ & J.J. Odimim²

¹Livestock Health Research institute, P.O. Box 96, Tororo, Uganda.
²FITCA (Uganda), Ministry of Agriculture, Animal Industry and Fisheries, P.O. 531, Entebbe, Uganda

Résumé

            Une étude conduite auparavant dans le district de Soroti en Ouganda a révélé que le bovin zébu Nkedi (n = 1.215) avait une plus faible prévalence d’infection trypanosomienne (7,9% contre 10,8% ; P>0,05) et une valeur moyenne de l’hématocrite beaucoup plus élevée (29,4% contre 28,7% ; P<0,05) que le bovin Ankole (n = 260) dans les mêmes conditions sur le terrain. Une étude de suivi de 100 bovins dans la même région (zébu Nkedi, n = 73 et Ankole, n = 27), qui pâturaient sous forte pression glossinaire a encore montré que le zébu Nkedi a une plus faible prévalence d’infection trypanosomienne (8% contre 11%) et une valeur moyenne de l’hématocrite élevée ±ES (29,84 ± 0,42 contre 28,90 ± 0,90) que l’Ankole. Ces résultats préliminaires indiquent que le zébu Nkedi contrôle mieux les effets de la trypanosomose que l’Ankole dans des conditions de forte pression glossinaire et ceci pourrait être exploité pour le contrôle de la trypanosomose animale. Des études de suivi, qui utilisent l’infection trypanosomienne expérimentale et naturelle des deux races, sont en cours.

Summary

            Evidence from an earlier study conducted in Soroti district, Uganda showed that Nkedi Zebu cattle (n = 1215) had a lower prevalence of trypanosome infection (7.9% v. 10.8%; P>0.05) and a significantly higher mean PCV (29.4% v. 28.7%; P< 0.05) than in the Ankole (260) kept under similar field conditions. A follow up study in the same area on 100 cattle (Nkedi Zebu, n = 73 and Ankole, n = 27), grazing under high trypanosome challenge still suggests, Nkedi Zebu exhibit lower prevalence of trypanosomosis (8% vs 11%) and higher mean PCV ± SE (29.84 ± 0.42 vs 28.90 ± 0.90) than Ankole cattle. Further studies have shown that Ankole cattle have either similar or lower prevalence of trypanosomosis than Nkedi Zebu cattle under medium trypanosome challenge, but have lower mean PCV than Nkedi Zebu cattle. However, under low trypanosome challenge, both Ankole and Nkedi Zebu cattle exhibit similar prevalence of trypanosomosis and mean PCV. These preliminary results suggest that Nkedi Zebu cattle might have a superior control of effects of trypanosomosis than Ankole cattle under high tsetse challenge, thus could be exploited in the control of animal trypanosomosis. Follow-up studies using both experimental and natural trypanosome infection of two breeds are underway.

Introduction

            Trypanosomosis is major constraint to cattle production in Uganda. Existing reports indicate the prevalence of trypanosomosis in cattle in Uganda is 11.9 % under the intensive dairy system and 25 % under the communal grazing systems (Magona and Mayende, 2002). Zebu and Sanga breeds constitute over 95% of the cattle of population (6.8 million) in Uganda (Magona and Mayende, 2002). There is growing evidence that indicates that there is difference in susceptibility to trypanosomosis between the Nkedi Zebu and Ankole cattle- Nkedi Zebu cattle tend to exhibit a lower prevalence of trypanosome infection and a significantly higher mean PCV than in the Ankole under similar field conditions (Magona et al., 2004). This difference in susceptibility between the two breeds has been reflected in past by the distribution of these cattle breeds countrywide in Uganda according to the trypanosome challenge. Traditionally, Nkedi Zebu that are smaller in size with a cow standing 101 cm and weighing 285 kg and a bull standing high 104 cm and weighing 360 kg on average (Magona et al., 2004), have been the main breed kept in tsetse-infested areas in Uganda where the trypanosome challenge is high e.g. Eastern Uganda. While Ankole cattle that are bigger in size with a cow standing at 130 cm weighing up to 350kg and a bull 145 cm weighing up to 450 kg (Magona et al., 2004) have been the main breed kept in tsetse-free areas or areas of low trypanosome challenge e.g. Western Uganda. Recent restocking programme in Uganda is aimed at improving cattle production to alleviate poverty especially in areas where cattle have been depopulated due to civil conflicts that have led to changes in the distribution of the two cattle breeds. The more susceptibility Ankole due to their attractive attributes-higher milk yield, draught power output and higher prices fetched, have been taken to tsetse-infested areas of high trypanosome challenge, where they graze side by side with Nkedi Zebu. Therefore studies were conducted to assess the prevalence of trypanosomosis and mean PCV of Nkedi Zebu and Ankole cattle grazing together in areas with different levels of trypanosome challenges to give indication of differences in production performance. In addition, the ratio of the different breeds-an indication of variation in distribution and farmers’ response in terms of trypanosomosis control were assessed.

Materials and Methods

Selection of study areas

            Two districts where Nkedi Zebu and Ankole cattle are kept together were visited. In each district one subcounty where both breeds of cattle were found was selected. In each district 400 cattle were sampled. Cattle were selected from all herds presented for sampling by cattle owners. Overall, 800 cattle belonging to 75 herds having a total of 1813 cattle were sampled from Opunoi, Osamito, Aarapoo, Aswii villages in Soroti district, and Katoma and Galiraya villages in Kayunga districts (Table 1).

Table 1: Cattle numbers in the herds sampled in the various villages

Blood examination

            Cattle were bled from the jugular and the blood was examined using both the Haematocrit centrifugation technique (Woo, 1969) and the Buffy coat technique (Murray et al., 1977) for trypanosomes. Trypanosome species identification was based on morphological differentiation on Giemsa-stained thin films. Packed cell volume (PCV) was measured using a PCV reader (Hawksley, England).

Trypanosomosis control status

            Seventy-five (75) cattle owners were interviewed on routine tsetse and trypanosomosis control measures involving either vector control through regular spraying cattle or treatment with trypanocidal drugs.

Results

            Regarding breed ratios, in 43 herds from areas of medium tsetse challenge, the ratio of Nkedi Zebu to Ankole was 50: 50. However, in 32 herds from areas of low tsetse challenge, there were 2-5 times more Ankole cattle than Nkedi Zebu.

            Distinctly, areas with low tsetse challenge had bigger cattle herds (average 50 cattle per herd) than areas with medium tsetse challenge: average 5 cattle per herd (Table 1).

            In these areas dominated by Ankole cattle farmers routinely spray their animals with insecticides to control tsetse and treat them with trypanocidal drugs independent of the tsetse challenge.

            The prevalence of trypanosomosis in Ankole and Nkedi Zebu cattle under medium challenge is shown in Table 2. In villages where the prevalence of trypanosomosis in Ankole cattle was either similar or lower than that of Nkedi Zebu cattle, Ankole cattle had lower mean PCV than Nkedi Zebu cattle.

Table 2: Prevalence of trypanosomosis in Ankole and Zebu cattle under medium tsetse challenge

            The prevalence of trypanosomosis in Ankole and Nkedi Zebu cattle under low tsetse challenge is shown in Table 3. Both Ankole and Nkedi Zebu cattle had similar prevalence of trypanosomosis and mean PCV.

Discussion

            In the present study, differences in susceptibility to trypanosomosis between Ankole and Nkedi Zebu cattle kept under different levels of trypanosome challenges were assessed. Regarding breed ratios, the ratio of Ankole to Nkedi Zebu was 50: 50 areas of medium trypanosome challenge, while Ankole cattle were 2-5 times more than Nkedi Zebu in areas of low trypanosome challenge. Suggesting cattle owners cope with trypanosomosis by keeping more susceptible cattle breeds away for medium to high trypanosome challenge (Magona et al., 2004).

            The study revealed that areas with low trypanosome challenge had distinctly bigger cattle herds than those with medium tsetse challenge. This difference in herdsize has been associated with bovine trypanosomosis in that it leads to sub-optimal stocking rate (Swallow et al., 1999; Magona et al., 2005).

Table 3: Prevalence of trypanosomosis in Ankole and Zebu cattle under low tsetse challenge

            In areas dominated by Ankole cattle farmers routinely sprayed their animals with insecticides to control tsetse and treated them with trypanocidal drugs independent of the tsetse challenge. Suggesting that cattle owners were aware of high susceptibility to trypanosomosis Ankole cattle exhibited. Infact under medium trypanosome challenge, the prevalence of trypanosomosis in Ankole cattle was either similar or lower than that of Nkedi Zebu cattle, but Ankole cattle had lower mean PCV than Nkedi Zebu cattle. This has similarly been observed before (Magona et al., 2004), suggesting Nkedi Zebu probably control effects of trypanosomosis better than Ankole. However, under low trypanosome challenge, there was no difference between Ankole and Nkedi Zebu in terms of prevalence and mean PCV.

            It is clear from this study that Ankole cattle-having good attributes of higher milk yield, higher draught power output and high prices fetched, could be taken to areas of low trypanosome challenge during restocking, but under medium to high challenge, they required regular good tsetse and trypanosomosis control programmes to keep them alive, otherwise the Nkedi Zebu do better under such conditions with little healthcare. The distribution of various indigenous cattle breeds in Uganda vis-à-vis trypanosome challenge needs to be studied to guide the countrywide restocking to ensure rearing of cattle breeds in suitable areas where optimal productivity can be achieved.  

Acknowledgement

            We wish to thank Geoffery Odyek, Joseph Muboli and Robert Wabyanga for their technical assistance. This paper is published with the permission of Director, Livestock Health Research Institute.

Reference

Magona, J.W., Walubengo, J., Odiit, M., Okedi, L.A., Abila, P., Katabazi, B.K., Gidudu, A.M, Olaho-Mukani, W. (2005). Implications of the re-invasion of Southeast Uganda by Glossina pallidipes on the epidemiology of bovine trypanosomosis. Veterinary Parasitology, 128 (1-2), 1-9.

Magona, J.W. Walubengo, J., & Odimim, J.J. (2004). Differences in susceptibility to trypanosome infection between Nkedi Zebu and Ankole cattle under field conditions in Uganda. Annals of Tropical Medicine and Parasitology, 98(8), 785-792.

Magona, J.W., Mayende, & J.S.P. (2002). Occurrence of concurrent trypanosomosis, theileriosis, anaplasmosis and helminthosis in Friesian, Zebu and Sahiwal cattle in Uganda. Onderstepoort Journal of Veterinary Research, 69, 133-140.

Swallow, B. W. (1999). Impact of trypanosomiasis on African agriculture. Programme Against African Trypanosomosis (PAAT) Position Paper 1999.