Application of replacement theory in dairy cows and its use in disease treatment
开发了一个模拟奶牛14年成本和收益的模型，用于评估疾病对生产和繁殖效率的影响，并以卵巢囊肿为例分析治疗的经济性，发现治疗比不治疗更经济，且GNRH优于HCG。
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).