A distinction is drawn between the non-specific resistance to heartwater of very young calves and that of cattle older than a year. The suckling-calf resistance is at its greatest during the first few weeks after birth and then gradually declines during the next 6-8 months. Aspects of its possible mechanism and significance are discussed. The role played by conglutinin in the natural resistance of older cattle to heartwater and in the epidemiology of the disease is discussed.
The 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.