Assessment Of Major Livestock Diseases And Associated Production Constraints In A Smallholder Production System In Machakos County, Kenya.

Abstract

This thesis describes livestock production constraints in a smallholder production system in Machakos District with special reference to tick-borne diseases. The objectives of the study were: (i) To identify the constraints that limit smallholder livestock production as perceived by various stakeholders in Machakos District; (ii) To establish the socio-economic and demographic characteristics of livestock farmers in the district; (iii) To estimate the seroprevalences of tick-borne diseases in the district; (iv) To estimate the morbidity, mortality and productivity parameters of livestock in the district; (v) To evaluate the efficacy of East Coast fever immunization of cattle by the infection and treatment method in the district. A three-stage cluster sampling method involving (in descending order of size) divisions, sub-locations, and households was used to select farms for the cross-sectional survey. A total of 200 farms were selected in four divisions. Farm level and individual animal data were collected using a standard questionnaire. Blood samples were collected from cattle in the farms and their sera screened for antibodies to Theileria parva, Babesia bigemina and Anaplasma marginale using ELISA tests. Fourteen farms were randomly selected for a one-year follow-up study. Data collected during follow-up included birth weights, disease occurrence, herd dynamics, weaning weights and ages, fertility and breeding female management, milk production, tick challenge, and tick control. Twenty-eight farms were randomly selected for conducting the controlled trial of the infection and treatment method of immunization of cattle against East Coast fever. Only calves and yearlings were recruited into the study. Study animals were randomly allocated to either the treatment or control group in each of the 28 farms. Animals in the xvi treatment group were injected with a long acting tetracycline (30%) followed by injection of the Marikebuni strain of Theileria parva vaccine stabilate. All the study animals on the 28 farms were followed-up equally via monthly visits for a period of 12 months. Data were collected on pre and post-immunization serological status of the animals including morbidity and mortality during the follow-up period. The main constraints to livestock production identified in order of importance included livestock diseases (mostly tick-borne diseases), poor access to livestock and livestock product markets, poor veterinary infrastructure and inadequate feed. The mean antibody sero-prevalence rates in the study sub-locations for Theileria parva, Anaplasma marginale and Babesia bigemina were 58.9%, 35% and 41.1%, respectively. East Coast fever was found to exit in a state of endemic stability characterized by high antibody prevalence and a constant tick challenge while anaplasmosis and babesiosis appeared to exist in a state of endemic instability, characterized by low antibody prevalence in all the four study divisions. In univariate analyses five factors (age, breed, division, grazing system, and tick infestation) were significantly (p<0.05) associated with testing positive to Theileria parva infection while age, division, grazing system and tick infestation were significantly (p<0.05) associated with testing positive to Anaplasma marginale infection; age, grazing system and division were associated (p<0.05) with testing positive to risk of exposure to Babesia bigemina infection. In multivariate analysis the only factors that were associated with testing positive to T. parva were age, division, grazing system and tick infestation while for anaplasmosis only age and division were significant. The same factors that were significantly associated with babesiosis in univariate analysis did not change in the mutltivariate analysis suggesting that the association was not confounded by any of the considered factors. Twenty-six (26) cases of ECF were confirmed on the 14 farms during the longitudinal study converting to an annual incidence rate of 30.7% per cow-year. Factors that were significantly (p< 0.05) associated with the risk of infection with by T. parva were age, tick control, frequency of acaricide application, season, and division. Four cases of anaplasmosis were confirmed converting into an annual incidence rate of 4.26%. Other conditions/infections observed in cattle during follow-up included malnutrition, mange, mycosis and diarrhoea. Eleven cattle died during the follow-up period converting to an overall crude mortality rate of 11.6% per cow-year. The cause-specific annual mortality rates of ECF, non-specific disease condition, and diarrhoea were 6.56%, 8.74% and 2.19% per cow-year, respectively. The commonest causes of morbidity in sheep and goats were helminthosis and pneumonia. Diarrhoea due to bacterial infections, severe flea infestations and mange were the other diseases detected in small ruminants. Livestock productivity was found to be sub-optimal. Cattle were reared primarily as long term investments while goats, sheep and poultry were often sold to meet immediate family financial needs. The daily mean milk production for cattle was 1.98 litres. Breeding intervals for goats and sheep were once every 12 month and the mean off- take rates for cattle and small ruminants were 9% and 4%, respectively. A high proportion (93.7%) of the cattle sero-converted following immunization against East Coast fever using the infection and treatment method. The annual incidence rate of ECF in the control group was 42.2% per cow-year and 7.8% per cow-year in the vaccinated group. The efficacy of the vaccine was 82%, indicating a significant protective effect in the study area. Use of the vaccine was found to be financially profitable and realized a net return of Ksh.2, 838 per animal. In conclusion, farmers need to be encouraged to keep improved livestock breed, particularly the exotic dairy (breeds) to address the problem of low milk production in the district. There is also a need to create awareness on the use of East Coast fever vaccine to reduce mortality from East Coast fever among calves and also enable more widespread introduction of exotic breeds of cattle. Co-operatives dealing in livestock and livestock products should also be formed or existing ones strengthened to assist in the marketing of livestock and livestock products. There is need to improve on the delivery of animal health services particularly the revival of tick control programmes in the district so as to optimize livestock productivity