CONSERVATION OF TRYPANOTOLERANT ORMA-BORAN THROUGH UTILISATION

PRESERVATION DE L’ORMA-BORAN TYPANOSOTOLERANT PAR LE BIAIS DE SON UTILISATION

Maichomo, M.V., Orengo, C.O., Munga, L.k. Nyamwaro, S.O and Ndungu J.M. KARI-TRC, P.O Box 362, Kikuyu, Kenya.

            L’élevage des races trypanotolérantes a été identifié comme l’une des approches durables de la lutte contre la trypanosomose dans les zones infestées par les tsétsé au Kenya. Cependant, le nombre limité d’animaux trypanotolérants a retardé leur adoption généralisée. Dans un souci de préserver le bétail Orma Boran (OB) trypanotolérant que l’on trouve au Kenya et de satisfaire la demande de ces taureaux dans les zones infestées par les tsétsé du pays, le Centre de recherche agricole du Kenya/le Centre de recherche sur la trypanosomose (KARI-TRC) a fondé un troupeau reproducteur en 1985 au ranch de Galana. Le programme consiste à identifier des taureaux génétiquement supérieurs à des fins de multiplication et de diffusion sur la base de taux de croissance élevés et de la capacité à tolérer l’infection trypansomienne. Le troupeau de race supérieure est introduit dans les troupeaux fondateurs et soumis à une forte pression glossinaire. Cette diffusion s’est opérée sur deux sites, à savoir : Busia et Kajiado. A ce jour, environ 300 zébus croisés Orma/Zébu F1 et F2 mis bas dans ces régions ont un bon rythme de croissance, une forte résistance à la trypanosomose et un meilleur taux de survie pendant la sécheresse. Compte tenu de la prise de conscience désormais plus poussée de l’importance de cette race bovine, elle fait l’objet d’une forte demande qui requiert une grande multiplication. Cela permettra d’éviter l’érosion de la trypanotolérance chez les OB, tout en favorisant son intégration progressive dans les autres races locales. Ce processus est actuellement en cours à travers la création de troupeaux reproducteurs dans les parcours de Kiboko et dans le ranch communautaire d’Olchorro Oiruwua.

Summary

            Stocking of trypanotolerant breeds has been identified as one of the sustainable approaches to trypanosomosis control in tsetse infested areas of Kenya. However, limited numbers of trypanotolerant animals has hindered their widespread adoption. This has drawn local and international attention necessitating the need to conserve local trypanotolerant breeds. In an effort to conserve the trypanotolerant Orma Boran (OB) cattle found in Kenya, the Kenya Trypanosomosis Research Institute (KETRI) established a breeding herd in 1985 at Galana ranch. This was followed by demand driven dissemination of bulls to tsetse infested areas of the country. The programme involves identification of superior OB genetic material for use for multiplication and dissemination purposes based on higher growth rates and ability to tolerate trypanosomosis infection. The superior stock are recruited into nucleus breeding herds and subjected to high levels of tsetse challenge. Two sites where this dissemination has been done include Busia and Kajiado districts. So far there are approximately 300 both F1 and F2 Orma Zebu crosses in the areas with observed good growth rate, resistance to trypanosomosis and better survival after drought. With increased awareness of the breed, which has been registered, there exists high demand requiring its further multiplication. This will prevent erosion of trypanotolerance in the OB while assisting its introgression into other local breeds. This is being addressed by setting up of breeding herds at Kiboko range reserve and Olchorro Oiruwua group ranch.

Introduction

            Large areas of East Africa are tsetse infested and trypanosomosis poses a threat to livestock health and productivity. In Kenya, over 60% of the country's total landmass which supports over half of the country's national cattle herd is tsetse infested, and may benefit from use of trypanotolerant breeds. Trypanotolerance is described as the relative capacity of an animal to control the development of parasites, and to limit their pathological effects, the most prominent of which is anaemia (Murray et al., 1990). Its degree in African cattle reflects severity of tsetse challenge and length of time of exposure (Dolan, 1998). Use of trypanotolerant animals in such areas optimises production, a practice widely associated with Bos taurus breeds of West Africa. The trait was described in indigenous East African breeds as early as 1913 such as the Zebu in Sudan (Mongalla), the Lugware of Zaire, Uganda and Suda (Joshi et al., 1957) and the Zebu of Kenyan L.Victoria shores (Cunningham, 1966).

            Despite these reports, much research on trypanotolerance has been on W.African breeds. However, from the 1980s, some efforts have been made to investigate the nature and/or extent of differential susceptibility to trypanosomosis amongst cattle breeds of East Africa. The Kenyan Orma Boran has been the focus of studies conducted by KETRI resulting in establishment of a breeding herd in Galana ranch in 1985 (Dolan, 1998). This breed kept by the Orma people of Tana River district is more productive than other indigenous breeds in medium to high tsetse challenge (Njogu et al., 1985). They are able to control development of parasitaemia and anaemia, and may at times recover without treatment (Dolan, 1998). Likewise, they require fewer drugs, criteria likely to check on development of drug resistance.

            Survey of Orma Boran cattle in Tana River district in 1998 revealed that there are 208,089 heads of cattle based on reports of a vaccination campaign (Irungu et al., 1999). Village level assessment of weaning weight was 78kg compared to 107kg reported at Galana ranch. Their potential having been realised, it was necessary to select best genotypes of Orma Boran based on high growth rate for multiplication and dissemination to tsetse infested areas of Kenya. Performance of animals disseminated to other areas ranged from good to average depending on environmental conditions, mainly pasture availability. For appropriate exploitation of the breed, KETRI with the help of ODA and livestock diversity experts planned a long-term evaluation program with the following objectives:

1. Conservation of the Orma Boran breed through utilisation
2. Survey of Orma tribe and their cattle keeping practices in Tana River district.
3. Assessment of the performance of these cattle in other tsetse infested areas of Kenya.
4. Characterisation of the breed for milk yield.

            All these components have been addressed in one way or another and this report focuses on objective 1, conservation of the Orma Boran breed through utilisation.

Materials and methods

            The foundation stock for the Orma Boran breeding herd was purchased from the Orma people and maintained under high tsetse challenge on Galana ranch from 1983. Through to 1997, consequent generations formed the basis for the Orma breeding herd and selection program aimed at improving growth rate characteristics. Weaners with average and above average growth rate were selected to join the breeding bull herd at 15 and 18 months of age. Such bulls were first for breeding between 42 and 48 months of age. No artificial selection was applied to cows. The trait of choice was post-weaning growth rate, a trait with medium to high heritability and frequently used in beef production breeding programs. The trait also responds well to selection. These animals were weighed monthly and blood screened every two weeks for trypanosomes using buffy coat technique.

Establishment of Orma breeding herds at Kiboko and Narok

            In 1999, it was thought wise to translocate the OB breeding herd from Galana to Kiboko due to anticipated change of management at Galana ranch that would result to inconveniences in research work. These animals were monitored monthly for weight gains, trypanosome prevalence and tsetse trapping was also done. Partly this also aimed at assessing the performance of the breed in different ecological zones, other than that of origin. Complementary information on milk yield was gathered by taking average yield of 2 days in a week (milking was done in 2 quarters while the other 2 were left for the calf to suckle, and yield got was multiplied by 2). From this breeding herd bulls were disseminated to Busia and Kajiado districts. Thereafter a lot of demand for the bulls was recorded which KETRI could not meet immediately. As a result KETRI has established another breeding herd in South West Kenya at Olchorro Oiruwua group ranch in 2003.

Dissemination of OB bulls to Kajiado and Busia districts

            This was in response to an expressed demand by farmers followed by physical examination of traits that they considered appealing to them. Once delivered, bulls were assessed on their adaptability in their respective environments, and response to trypanosomosis and tick borne disease (TBD) challenge using questionnaires, buffy coat technique and dry smears respectively. This was also repeated in the F1 cross calves (between the OB and the Zebu cows). The cross calves at Kajiado were also assessed for growth rate at weaning (8 months) and at 18 months.

Results

            An Orma Boran breeding herd was established at Galana ranch in 1983 from a parent stock of 231 females and 5 bulls purchased from the Orma people. Over twelve years (upto 1995), 448 cows were recorded and 381 gave birth to a total of 904 calves. Male calves with below average growth rate were culled and eventually 528 bulls were available in the breeding herd. Three observations made on collected data indicated improvement in productivity of the herd: (i) Improvement of birth weight, (ii) reduction of heifer age at first calving from 4 years to 3 years 7 months and (iii) reduction in growth rate variance from 98 to 22g/day. Using the same data, repeatability values for cows PCV, infection rates and body weight were estimated at 26%, 40% and 50% respectively. Heritability estimates of calves born at Galana ranch for birth weight, weaning weight and PCV were medium to high, which is a suitable selection criterion..

Establishment of breeding herds at Kiboko and Narok

Kiboko

            A foundation stock from Galana ranch consisting of 58 heifers and 2 bulls were translocated to Kiboko between 1999 and 2001. It is out of this initial herd that atotal of 85 calves have been born and bistributed to farmers at Kajiado and Busia (tesoland) districts. 10 lactating cows in this herd have revealed that 3-10 litres of milk can be obtained from an Orma cow/day. The average birth weight for the Orma calves is also recorded as 20.5kg and the age to first calving is 3.8 years.

Narok

            Twenty nine OB heifers and bulls were translocated to Narok. While undergoing multiplication, this herd will also be used for research purposes to address the following issues: (i) Comparison of disease resistance and production performances of the Orma cattle with the small East African zebu under the same environment, (ii) Resistance to other disease parasites not found in place of origin and, (iii) Adaptability to different environments. The information will be necessary in order to determine to what extent the trypanotolerant breeds can be used in face of other parasitic diseases

Dissemination of OB bulls to Kajiado and Busia districts.

            Orma Boran bulls have been delivered twice to Nguruman in Kajiado district, first 12 in 1996, and 14 others between July 2002 and January 2003 as shown in Table1. Of the first 12, 8 died over 1 year period . the death cause was not conclusively established, but was suggested to be either ECF and/or severe starvation associated with 1995 - 1997 drought that nearly decimated livestock population in the country. Of the other 5, 3 were sold of for slaughter while 2 were sold to Tanzania for breeding.  However, 150 F1 Orma/Zebu cross calves were left behind and showed remarkable survival during the drought compared to the Maasai zebu calves. At 18 months, the crosses body weight exceeded that of the Maasai Zebu by 40kg . To date, these F1s have produced 90 F2 calves. Significant difference in trypanosome infection rate was observed between the O/Z and MZ calves during high tsetse challenge. The latter 14 bulls are about to bring forth offspring's, that will be a resource population for molecular analysis of trypanotolerance in the Orma Boran.

Table 1: Number of Orma Boran bulls disseminated to Kajiado and Busia districts
between 1996 and 2003.

            In Busia district, eight bulls were delivered in August 2001. Currently 4 bulls are alive and 4 have since died due to ECF. To date there are twenty-eight Orma/Zebu cross calves from the bulls.

            Comparisons done regarding susceptibility of OB breed to tick infestation showed that the breed had low susceptibility to Rhipicephalus appendiculatus and Boophilus compared with Galana Boran and likewise acquired ECF less often. However, the Maasai Zebu performed better for both attributes while the Friesian was the most susceptible.

Discussion

            The rapidly increasing human population in Africa is associated with the challenge of satisfying a dramatic increase in demand for livestock products. Areas with the greatest potential for significant increases in livestock population and hence productivity have tsetse transmitted trypanosomosis as a major constraint to agricultural development (Winrock international, 1992). While the eradication of trypanosomosis from the entire continent is long-term goal, considerable effort has been invested in the control of this disease through use of trypanocidal drugs, vector management and exploitation of genetic resistance of indigenous breeds. Though each of these methods has shortcomings, use of trypanotolerant Orma Boran is more promising. There is need therefore to enhance trypanotolerance through selective breeding, multiplication and dissemination.  Trypanotolerance involves a significant degree of genetic control that is highly heritable and is most obviously controlled by two or more genes. It is characterised by improved parasite control, the ability to maintain normal blood parameters, and remain productive in the face of challenge, which prove fatal to susceptible cattle types.

            The future utilisation of the genetic resource represented by trypanotolerance cattle to harvest the biomass of much of tsetse-infested Africa depends on their conservation, promotion and improvement (Bradley, 1998). Like the many trypanotolerant breeds of West Africa face extinction due to introgression by other large breeds, Kenyan pastoralists, are observed to cross their animals with Sahiwal and improved Boran breeds. This mainly is an effort to breed animals with higher market weight, hence a better source of income. The danger of indiscriminate cross breeding is that unique genetic resources could be depleted with time as world agriculture is currently observed rely on few animal species and fewer breed lines.

            Farmers appreciate that OB weight and therefore market value is somewhere in between that of the Maasai Zebu and the Sahiwal/Boran/Zebu crosses but they tolerate trypanosome infection and require less feed (hence are more productive.  Infact the breed has been associated with a good omen by the Maasai pastoralists due to increase in herd turnover observed)

            The breeding and dissemination of trypanotolerant cattle has many attractions.  It would reduce reliance on chemotherapeutic and insecticidal agents with consequent reduction in the negative environmental effects of widely practiced current control methods. Trypanotolerance has been ascertained in the N’Dama and Orma Boran.  Infact, in East Africa, the OB cattle provide the only well documented case of Trypanotolerance. These animals have an added advantage over many of the other indigenous breeds in that they are faster growing with a large mature body weight (Maichomo et al,. 2000). Evidence of trypanotolerance has also been found in the Maasai Zebu cattle (Mwangi et al., 1998) and it is likely to occur in any breed with a long history of exposure to tsetse. For biological diversity, it is usually recommended that genetic resources be conserved in the surroundings where they have developed their distinct properties (Ilse Kohler-Rollefson, 2000) hence the establishment of the OB breeding herd at Galana ranch and improvement of subsequent generations through selection of superior males.

            Dissemination of superior bulls to tsetse-infested areas was demand driven, though it could have been influenced by the presence of KETRI in both Busia and Kajiado. In Kajiado, bulls were first delivered when pasture was very poor, which may have contributed to high disposal rate of the bulls through death, salvage slaughter and sale. The two bulls sold for breeding fetched a decent price of Ksh. 40,000 comparable to that of Sahiwal and improved Boran. The fact that some bulls died of ECF both in Busia and Kajiado suggests that the breed needs adjustment to the prevailing serodeme of theileria in an area. Otherwise, at Muguga the OB was shown to be fairly resistant to tick engorgement and ECF development compared to exotic breeds and Galana Boran (KETRI report, 2003). The observation that Orma/Zebu crosses in Kajiado were more productive than the Maasai Zebu controls during high rainfall season agrees well with reports by Dolan (1998) and Irungu (1999) that the Orma Boran is more economical hence productive when tsetse challenge is high. Otherwise in medium to low challenge, it makes no difference. This is further supported by presence of significant difference in trypanosomosis infection rate as well as growth rate between the OrmaZebu crosses and the Maasai zebu during high tsetse challenge, probably a phenomenon of enhanced trypanotolerance (KETRI reports, 2000).

            Its vital for KETRI to continue selection of superior stock into nucleus breeding herd to ensure steady supply to farmers in tsetse infested areas. Proposed studies on dissemination process will take into account farmer breed preferences and market values as has been proven in West Africa by Jabbar et al. (1997) to widely affect adoption of animal breeds.

Conclusion

            This report indicates that trypanotolerance in Orma Zebu crosses has been observed after dissemination of OB bulls to Kajiado district. This together with high growth rate and market value has tremendously increased demand for the OB in trypanosomosis endemic areas. KETRI therefore needs to continue with multplication of improved OB animals for dissemination purposes. This is a true refection of preservation of the OB breed through utilisation

Acknowledgements

            This work has been published with the permission of Director KARI and financial support was given by the G.O.K

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