Abstract

Extract

Disease surveillance systems can take many forms, depending upon what is desired of them. Surveys of mortality can be useful as an integral part of any surveillance system, both as a record of the losses and as an indication as to which conditions may be responsible for lowering the thrift of the population. Both these sources of loss are important in reducing the monetary return from a stock population as a whole. Surveys of mortality can indicate the importance of low incidence diseases and can be used to identify conditions previously unknown in the area. Totally new diseases can also be detected in this manner. Many individual disease conditions as well as surveys of groups of diseases (Hartley and Kater, 1962 Hartley, W. J. and Kater, J. C. 1962. Observations on diseases of the central nervous system of sheep in New Zealand. N.Z. vet. J., 10: 128–142. [Taylor & Francis Online] , [Google Scholar]; O'Hara and Shortridge, 1966 O'Hara, P. J. and Shortridge, E. H. 1966. Some diseases of the porcine central nervous system in New Zealand. N.Z. vet. J., 14: 1–12. [Taylor & Francis Online] , [Google Scholar]; Shortridge and Cordes, 1971 Shortridge, E. H. and Cordes, D. O. 1971. Neoplasms in cattle: A survey of 372 neoplasms examined at the Ruakura Veterinary Diagnostic Station. N.Z. vet. J., 19: 5–11. [Taylor & Francis Online] , [Google Scholar]) have been reported from material submitted to New Zealand laboratories and mortality studies on groups of animals have been undertaken elsewhere (Everitt and Evans, 1970 Everitt, G. C. and Evans, S. T. 1970. Beef production from a dairy herd: an analysis of mortalities. N.Z. vet. J., 18: 132–139. [Taylor & Francis Online] , [Google Scholar]; Jackson et al., 1972 Jackson, C. A. W., Kingston, D. J. and Hemsley, L. A. 1972. A total mortality survey of nine batches of broiler chickens. Aust. vet. J., 48: 481–487.  [Google Scholar]).