Feed Efficiency Versus Feed Conversion Ratio -- Demonstrated on Feeding Experiments with Juvenile Cod (Gadus Morhua)

19 Pages Posted: 20 Aug 2013 Last revised: 27 Jan 2014

See all articles by Eckhard Bethke

Eckhard Bethke


Matthias Bernreuther

Thünen Institute of Sea Fisheries

Ross Tallman

Fisheries and Oceans Canada

Date Written: August 20, 2013


Feed conversion ratio (FCR), which is used as a description of growth as a function of feed intake, depends mainly on the feeding rate but also on temperature. The estimation of the FCR is simple; however, the practical application of this ratio is limited to cases in which fish are fed beyond maintenance rate. In addition, FCRs are not comparable if they are measured at different temperatures. Ivlev (1939) proposed the more universal temperature independent metric K3 -- also known as feed efficiency. Even if the feed efficiency is a measure of the usable percentage of the food it has not been in common use in research and practice. This is most likely due to difficulties in determining this parameter in conjunction with temperature dependency of the maintenance rate and its temperature constant in practice. In this work we present an estimation method, which allows the determination of these parameters indirectly by the “system response” of fish. The parameter estimation is performed by least square fitting, comparing the food intake of the model with the food intake observed in feeding experiments with juvenile cod (Gadus morhua), carried out by Soofiani (1983) and Hawkins et al. (1985) over a wide range of feeding rates and temperatures. For individual fish, the model works not very accurately, while a comparison of the computed model results with the de facto consumed amounts (mean feed intake per fish and size group) demonstrates a high level of agreement. The relative estimation error is generally highest at the lowest consumption rates. The developed model is particularly suitable for the optimization of the feed ration at different temperatures in aquaculture systems.

Keywords: feed conversion ratio, feed efficiency, growth, maintenance rate, temperature

JEL Classification: Q0

Suggested Citation

Bethke, Eckhard and Bernreuther, Matthias and Tallman, Ross, Feed Efficiency Versus Feed Conversion Ratio -- Demonstrated on Feeding Experiments with Juvenile Cod (Gadus Morhua) (August 20, 2013). Available at SSRN: https://ssrn.com/abstract=2313137 or http://dx.doi.org/10.2139/ssrn.2313137

Eckhard Bethke (Contact Author)

FiCoBe ( email )

Königsbergstraße 54
Wedel, DE 22880
+49151 50203402 (Phone)

HOME PAGE: http://www.ficobe.de

Matthias Bernreuther

Thünen Institute of Sea Fisheries ( email )

Bundesallee 50
Braunschweig, 38116
+49 (0)40 38905 238 (Phone)
+49 (0)40 38905 264 (Fax)

HOME PAGE: http://www.ti.bund.de/en/startseite/institutes/sea-fisheries.html

Ross Tallman

Fisheries and Oceans Canada ( email )

501 University Crescent
Winnipeg, Manitoba R3T 2N6
+1 (204) 983-3362 (Phone)
+1 (204) 984-2403 (Fax)

HOME PAGE: http://umanitoba.ca/Biology/adjuncts/

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