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Abstract
A model to simulate the costs and returns of an individual dairy cow over 14 years under
various assumptions of genetic potential, health status and management was developed
especially to evaluate the effects of diseases that reduce production and reproduction
efficiency and to evaluate alternative management interventions. Data were collected from
the Food Animal Health Resource Management System (FAHRMX), Today's Electronic
Planning (TELPLAN), Today's Electric Farm Accounting (TELF ARM) databases and
secondary sources at Michigan State University. A case study of cystic ovaries was analysed
using the model. The results showed that it is more economical to treat cystic ovaries than not
to treat, and treatment with Gonadotropin Releasing Hormone (GNRH) was superior to
Human Chrionic Gonadotropin (HCG). Four to five lactations were the optimum for keeping
a dairy cow to replacement and it was estimated that there is a loss of US$0.45 per day of
extended calving interval (days open beyond the optimal 70 days).