Relationships among Feed Intake, Feed Efficiency, and Growth in Juvenile Rainbow Trout

Abstract

Improving the efficiency of aquaculture production is important for both economic and environmental sustainability. The purpose of this work was to define the relationships between feed intake, weight gain, and feed efficiency (measured as residual feed intake) in rainbow trout Oncorhynchus mykiss fed either to apparent satiation or a limited ration. The results indicated that under an apparent satiation feeding regime, a weak but significant correlation existed between weight gain and residual feed intake (RFI; r = −0.31, P < 0.04). When fed a limited ration, the correlation between weight gain and RFI was stronger (r = −0.57, P < 0.001). Genetic differences between family groups were detected only under the apparent satiation feeding regime and not under limited feeding. Although these experiments were conducted on different groups of fish, it appears that the variation in RFI was greater in satiation-fed fish than in fish fed a limited ration (coefficient of variation = 174% versus 33%). Estimates of residual feed intake measured on individuals from full-sib families and on groups of individuals from the same families were correlated (r = 0.66, P = 0.03), suggesting that the feed efficiency measured on individually reared fish captures a trait expressed in social groups as well.