BOVINE BRUCELLOSIS SERUM AGGLUTINATION-TEST PREVALENCE AND BREED DISPOSITION ACCORDING TO PREVALENT MANAGEMENT-SYSTEMS IN THE LAKE VICTORIAZONE OF TANZANIA

A total of 13 078 cattle 8 months of ape and older belonging to 558 un its in the Lake Victoria zone of Tanzania were screened for brucellosi s using the serum agglutination test (SAT). This exercise was executed as a Tanzanian Agriculture Ministry's directive for screening all adu lt bovines in the country reared under controlled grazing and receivin g good veterinary supervision and inputs so that brucellosis control m easures could be instituted, in this category two types of management systems were encountered: Dairy, comprising 15 units totalling 3626 Ex otic (Friesian and Ayrshire) and Grade (Zebu and Exotic) crosses, and Ranch, comprising two units totalling 6756 mainly dual-purpose Mpwapwa (MPW) animals. These three animal types have much higher milk product ion potential than the indigenous Tanganyika shorthorn Zebu (TSZ). Thi s latter beef type is reared under local management system and owned w holly by subsistence stock owners practising uncontrolled communal gra zing and having little or no veterinary supervision and inputs. Howeve r, TSZ animals from 541 farm units totalling 2705 members were also sc reened from the east and south sub-zones because of their close proxim ity to the Dairy/Ranch units and also the Serengeti Wildlife National Park. This exercise revealed an overall prevalence rate of 10.8%. Ther e was moreover a significant difference in the seroprevalence rates am ong the management systems (P < 0.001). The lowest prevalence rate (4. 3%) was found in the Local management system, with Dairy intermediate (6.3%) and Ranch highest (15.8%). There was also significant variation in prevalence rates between TSZ and Grade animals, and between MPW an d Exotic animals (P < 0.001).