An automated method and system for individual animal electronic identification, measurement, and management of cattle in a feedlot. Through the use of a computer system integrated with individual animal identification, multiple measurement and remeasurement systems, and a handling and sorting system, animals are individually identified and measured. The computer system calculates optimum slaughter weight, economic end point and marketing date for shipment to a packing plant. Individual animals are sorted by the computer in response to calculations from the measurements. The computer system stores individual animal measurement, performance and location data, which is used to select animals for shipment to slaughter at the optimum time. At the slaughter facility, the animal's identification is used to correlate the live animal physical characteristics and performance data to the carcass characteristics data and build a-database to more accurately identify and measure value-based characteristics in subsequent animals for more effective selection and management.