Du Plessis, J.L.Potgieter, F.T.Van Gas, L.Verwoerd, Daniel Wynand2014-09-012014-09-0120131990Du Plessis, JL, Potgieter, FT & Van Gas, L 1990, 'An attempt to improve the immunization of sheep against heartwater by using different combinations of 3 stocks of Cowdria ruminantium’, Onderstepoort Journal of Veterinary Research, vol. 57, no. 3, pp. 205-208.0330-2465http://hdl.handle.net/2263/41857The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.Neither sheep immune to the Ball 3, the Kwanyanga or the Mara stocks of Cowdria ruminantium nor those immunized with combinations of these 3 stocks were protected against challenge with the Mali stock. Against challenge with the Welgevonden stock, however, immunization with each of the 3 combinations and with single stocks effected a protective immunity.en©South Africa. Dept. of Agricultural Technical Services. ©University of Pretoria. Dept. of Library Services (digital).Veterinary medicineVeterinary medicine -- South AfricaArticle