Monitoring and analysis of health and production at farm level

Developing an understanding of interrelationships among health, production, and livestock management, particularly nutrition, requires a holistic approach to the evaluation of the farming system. For both economic and animal welfare reasons, a detailed understanding of the implications of farm management decisions, particularly those relating to the nutrition of the animals, on the health of livestock is required. This paper looks at two examples from recent research studies which demonstrate how management decisions in the field of nutrition can be related to overall levels of animal health. The first examines the relationship between the use of recombinant bovine somatotropin in dairy cattle and overall levels of health in treated cattle. The second looks at how feed composition may play a key role in determining the susceptibility of fish to the infectious salmon anaemia virus. There are two complementary approaches to studying nutrition, health and production interrelationships. The first, sometimes referred to as the empirical approach, relies on the use of epidemiological studies in commercial livestock operations to develop insights into specific relationships which can not be studied in experimental situations with small numbers of experimental animals. The challenges of observational studies, particularly the problems of monitoring health and nutrition, are discussed. Recent developments in some analytical methods which can assist in the conduct of observational studies are described. The second, sometimes referred to as the normative approach, uses simulation models to integrate the knowledge derived from empirical studies into systems which can evaluate the overall effects of management decisions. The use of simulation models in the application of epidemiological study results is presented..