Paulo Ignasius Prasso Pengarang SEBASTIANUS ADI SANTOSO MOLA Dosen Pembimbing 1 ARFAN YEHESKIEL MAUKO Dosen Pembimbing 2 Sebastianus Adi Santoso Mola Ketua Penguji Arfan Yeheskiel Mauko Penguji 1 Derwin Rony Sina Penguji 2

Based on data from Dinas Peternakan Kabupaten Kupang, the number of goat cases reported to have contracted the disease in Kabupaten Kupang continues to increase, where in 2018 there were 245 cases, and until 2020 it increased to 354 cases. For this reason, in caring for goats it is necessary to take appropriate and fast actions, in the process of handling diseases in goats, the use of an expert system which is a computer program containing knowledge from an expert can be used as a consultation facility to diagnose goat disease. In this study, there were 7 goat disease data, 23 goat disease symptom data as well as data on handling and control of the goat disease, which were obtained from interviews with experts or veterinarians who served in the Dinas Peternakan UPT Pembibitan Ternak dan Produksi Pakan Ternak Instalasi Sumlili, and in the process of developing an expert system for diagnosing goat diseases, the method is used certainty factor as an assessment parameter in measuring the level of confidence of experts or veterinarians against the symptoms of diseases that attack goats. After the expert system was successfully developed and was able to diagnose goat disease, the system accuracy test was carried out with expert justification, using 60 cases of goat disease simulation, and there were 49 similar diagnosis results so as to obtain a system accuracy percentage of 81.66%. So it can be concluded that the use of theMethod certainty factor can be applied to an expert system to diagnose goat disease based on website.