FCR = Feed Consumed / Weight Gained
FCR measures how efficiently an animal converts feed into body mass. Lower FCR = better efficiency. Typical FCR values: broiler chickens 1.6-1.9, salmon 1.1-1.3, pigs 2.5-3.5, beef cattle 5-8. FCR is the most important economic metric in animal agriculture because feed costs represent 60-70% of total production costs. Factors affecting FCR: genetics, feed quality, health status, environmental stress, and management. Improving FCR by 0.1 in a large poultry operation saves millions annually. Feed efficiency (FE = 1/FCR × 100) expresses the same concept as a percentage. Selection for improved FCR through genetics has halved poultry feed costs over the last 50 years.