Basic epidemiologic concepts related to assessment of animal health and performance.

Modern animal production systems are increasingly complex,which is why farmers depend on veterinarians to help them make sound decisions based on valid interpretation of data. While serving as advisors to farmers, veterinarians face the challenge of properly identifying key indicators of animal performance and differentiating between values that reflect normal biologic variation and those that require intervention. The veterinary consultant must understand the strengths and weaknesses of data, assess production trends accurately, and evaluate the results of management changes. This article describes some basic epidemiologic concepts about animal performance data. These concepts equip veterinary practitioners with the tools they need to give the best advice.