Trypanosomosis and phenotypic features of four indigenous cattle breeds in an Ethiopian field study

Abstract

We conducted a two-part study in the native home areas of four cattle breeds, Abigar, Gurage, Horro and Sheko, in south-western Ethiopia. The first part of the study investigated livestock keeper knowledge about trypanosomosis and trypanotolerance. For each breed 60 livestock keepers were interviewed, resulting in a total of 240 interviews. The second part of the study focused on biological evidence for trypanotolerance. Blood samples of about 100 head of cattle per breed were collected during peak trypanosomosis challenge period and analyzed for packed cell volume (PCV) and parasitaemia. In addition individual body measurements of the sampled animals were taken and the keepers provided some information regarding their animals. Livestock keeper interviews revealed that trypanosomosis was considered a major problem in all areas (95–100%). Almost all Abigar livestock keepers knew how trypanosomosis is transmitted, whereas only 34–52% of the keepers of the other breeds had that knowledge. Most Sheko keepers (75%) knew of trypanotolerance and claimed to have trypanotolerant animals in their own herds. Among the other three breeds the knowledge of trypanotolerance was much less (8–18%). A majority of the keepers were interested in purchasing trypanotolerant animals. PCV was highest among Horro (26.2) and Sheko (25.1) cattle whereas Abigar had the lowest PCV (20.0). Sheko were least infected by trypanosomes (6%) and had the lowest number of trypanocidal treatments per year (1 treatment/animal and year). Abigar cattle were most infected (23%) followed by Gurage (20%) and Horro (17%). Gurage had by far the highest number of treatments per animal and year (24). There were large differences between the number of cattle perceived by the keepers to be infected, and the number detected from blood sampled, among Abigar, Gurage and Horro. Sheko livestock keepers were better at correctly diagnosing trypanosomosis in their animals. It is concluded that Sheko cattle have higher trypanotolerance attributes of the breeds investigated and a better use of this breed could improve cattle health and household welfare in tsetse-infested areas.

Introduction

Traditional ways of controlling trypanosomosis, in Ethiopia as well as in other African countries, include injection of trypanocidal drugs and odor-baited traps as well as pour-on drugs aimed against the vector of the disease, tsetse flies. These methods are not only relatively expensive but also depend on reliable drug supplies. Another possible way to control trypanosomosis is by using trypanotolerant cattle in areas with high trypanosomosis challenge. Trypanotolerance is defined as the relative capacity of the animals to control the development of the parasites and to limit the pathological effects (d’Ieteren et al., 1998b). The most well known example of trypanotolerance in cattle is the West African taurus breed, the N’Dama cattle. They are known for their ability to produce and reproduce even under high trypanosome pressure. Despite this, livestock keepers in Nigeria deliberately select more Bos indicus breeds than trypanotolerant Bos taurus, based on milk production, ease of handling and market value (Jabbar and Diedhiou, 2003). Stein et al. (2009) reported that most livestock keepers wanted healthier but also more productive animals. Given the relative smaller body size of the tolerant breeds, there has been increased introduction of bigger trypanosusceptible breeds (e.g. the Zebu) in traditional breeding areas of trypanotolerant breeds (Rege, 1999). Consequently, the Bos taurus breeds are threatened by interbreeding with zebu breeds and the negative trend in number of trypanotolerant animals represent a great loss for tsetse infected areas.

The Sheko breed is a taurus type breed that is believed to be trypanotolerant (Alberro and Haile-Mariam, 1982, Epstein, 1971, Lemecha et al., 2006). Lemecha et al. (2006) found that, in the same tsetse infested environment, tested on an experimental farm, Sheko cattle showed better trypanotolerance attributes compared to the three Bos indicus breeds investigated, namely Abigar, Gurage and Horro. These four breeds are normally kept in different tsetse infested areas of Ethiopia. Stein et al. (2009) reported that livestock keepers in all the four areas considered trypanosomosis to be a major cattle disease. Furthermore, that study indicated that Sheko and possibly Abigar cattle might be more trypanotolerant than the other breeds. However, objective technical evidence based on animal ability to handle disease progression as well as clinical manifestation and treatment information was lacking.

The aim of this study was to document livestock keepers’ knowledge and perception regarding trypanosomosis and trypanotolerance and to objectively verify the findings by investigating Packed Red Cell Volume (PCV) and parasitaemia among the four cattle breeds. In addition, the study sought to phenotypically describe the breeds in terms of body size and body condition. The ultimate objective was to identify the breed or breeds with the best level of trypanotolerance among the four investigated on the premise that a more effective and sustainable use of trypanotolerant breeds would improve household welfare in tsetse infested areas.