title: Economic values of growth and feed efficiency for fish farming in recirculating aquaculture system with density and nitrogen output limitations: a case study with African catfish (Clarias gariepinus).
abstract: In fish farming, economic values (EV) of breeding goal traits are lacking, even though they are key parameters when defining selection objectives. The aim of this study was to develop a bioeconomic model to estimate EV of 2 traits representing production performances in fish farming: the thermal growth coefficient (TGC) and the feed conversion ratio (FCR). This approach was applied to a farm producing African catfish (Clarias gariepinus) in a recirculating aquaculture system (RAS). In the RAS, 2 factors could limit production level: the nitrogen treatment capacity of the biofilter or the fish density in rearing tanks at harvest. Profit calculation includes revenue from fish sales, cost of juveniles, cost of feed, cost of waste water treatment, and fixed costs. In the reference scenario, profit was modeled to zero. EV were calculated as the difference in profit per kilogram of fish between the current population mean for both traits (µt) and the next generation of selective breeding (µt+Δt) for either TGC or FCR. EV of TGC and FCR were calculated for three generations of hypothetical selection on either TGC or FCR (respectively 6.8% and 7.6% improvement per generation). The results show that changes in TGC and FCR can affect both the number of fish that can be stocked (number of batches per year and number of fish per batch) and the factor limiting production. The EV of TGC and FCR vary and depend on the limiting factors. When dissolved NH3-N is the limiting factor for both µt and µt+Δt, increasing TGC decreases the number of fish that can be stocked but increases the number of batches that can be grown. As a result, profit remains constant and EVTGC is zero. Increasing FCR, however, increases the number of fish stocked and the ratio of fish produced per kilogram of feed consumed ("economic efficiency"). The EVFCR is 0.14 €/kg of fish, and profit per kilogram of fish increases by about 10%. When density is the limiting factor for both µt and µt+Δt, the number of fish stocked per batch is fixed; therefore, extra profit is obtained by increasing either TGC, which increases the annual number of batches, or by decreasing FCR, which decreases annual feed consumption. EVTGC is 0.03 €/kg of fish and EVFCR is 0.05-0.06 €/kg of fish. These results emphasize the importance of calculating economic values in the right context to develop efficient future breeding programs in aquaculture.
authors.affiliation: Animal Breeding and Genomics Centre, Wageningen University, P.O. Box 338, NL-6700 AH Wageningen, the Netherlands AgroParisTech, UMR1313 Génétique animale et biologie intégrative, 16 rue Claude Bernard, F-75231 Paris 05, France INRA, UMR1313 Génétique animale et biologie intégrative, Allée de Vilvert, F-78350 Jouy-en-Josas, France mathieu.besson@wur.nl.
authors.forename: M
authors.initials: M
authors.lastname: Besson
authors.affiliation: Animal Breeding and Genomics Centre, Wageningen University, P.O. Box 338, NL-6700 AH Wageningen, the Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Komen
authors.affiliation: INRA, Agrocampus Ouest Rennes, UMR1069 Sol Agronomie Spatialisation, 65 rue de Saint Brieuc, F-35042 Rennes, France.
authors.forename: J
authors.initials: J
authors.lastname: Aubin
authors.affiliation: Animal Production Systems group, Wageningen University, P.O. Box 338, NL-6700 AH Wageningen, the Netherlands.
authors.forename: I J M
authors.initials: IJ
authors.lastname: de Boer
authors.affiliation: IMARES, Wageningen UR, Korringaweg 5, NL-4401 NT Yerseke, the Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Poelman
authors.affiliation: INRA, UMR1313 Génétique animale et biologie intégrative, Allée de Vilvert, F-78350 Jouy-en-Josas, France.
authors.forename: E
authors.initials: E
authors.lastname: Quillet
authors.affiliation: Fishion Breeding, Breedijk 13, NL-5705 CJ Helmond, the Netherlands.
authors.forename: C
authors.initials: C
authors.lastname: Vancoillie
authors.affiliation: INRA, UMR1313 Génétique animale et biologie intégrative, Allée de Vilvert, F-78350 Jouy-en-Josas, France IFREMER, Chemin de Maguelone, F-34250 Palavas-les-Flots, France.
authors.forename: M
authors.initials: M
authors.lastname: Vandeputte
authors.affiliation: Animal Breeding and Genomics Centre, Wageningen University, P.O. Box 338, NL-6700 AH Wageningen, the Netherlands.
authors.forename: J A M
authors.initials: JA
authors.lastname: van Arendonk
mesh_terms: D000821:Animal Feed / Q000032:analysis* / Q000191:economics; D000818:Animals; D017756:Aquaculture / Q000191:economics* / Q000379:methods*; D001947:Breeding / Q000379:methods*; D002397:Catfishes / Q000254:growth & development*; D018803:Models, Economic; D012641:Selection, Genetic; D013696:Temperature; D018508:Water Purification / Q000191:economics
keywords: economic values; feed conversion ratio; fish farming; recirculating aquaculture system; selective breeding; thermal growth coefficient