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Proactive coping style in early emerging rainbow trout carries a metabolic cost with no apparent return

Skov, Peter V.; Joao de Jesus Gregersen, Kim; Gesto, Manuel and Jokumsen, Alfred (2019) Proactive coping style in early emerging rainbow trout carries a metabolic cost with no apparent return. [Proaktiv adfærd med tidlig fødesøgning medfører en netto metabolsk omkostning hos regnbueørred.] Comp. Biochem. and Physiol., Part A, 231, pp. 104-110.

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Summary

The timing with which salmonid larvae emerge from their gravel nests is thought to be correlated with a particular suite of behavioural and physiological traits that correspond to the stress coping style of the individual. Among these traits, aggressiveness, dominance and resilience to stress, are potentially interesting to exploit in aquaculture production. In the present study a series of experiments were performed, with the purpose of characterising behavioural, metabolic and production related traits in rainbow trout juveniles from different emergence fractions. Newly hatched rainbow trout were sorted according to their emergence time from an artificial nest. The early, middle, and late fractions were retained and assessed for their physiological response to stress, growth performance, metabolism, fasting tolerance, and potential for compensatory growth. The early emerging fraction showed proactive behavioural traits; they were faster to reappear following startling, showed a reduced cortisol response following stress,and a reduced metabolic cost of recovery. Emergence time was not correlated with any differences in standard or maximum metabolic rates, but was however, correlated with higher routine metabolic rates, as demonstrated by significantly bigger weight losses during fasting in the early emerging group. Growth rates and feed conversion efficiencies were not significantly different when fish were co-habitated under a restrictive feeding regime, suggesting that early emerging fish are not able to monopolize food resources. The intermediate emerging group, which makes up the bulk of a population and is often ignored, appears to possess the best growth performance traits, possibly because they do not expend excessive energy on dominance behaviour such as the early emerging group, while they are also not overly timid or stress prone such as the late emerging group.

Summary translation

Det antages, at tidspunktet, hvor yngel af laksefisk forlader grus-reden på bunden (”swim-up”), er korrelleret med en række særlige adfærdsmæssige og fysiologiske egenskaber, som knytter sig til individets stress håndtering. Blandt disse egenskaber kan “aggressivitet”, ”dominans” og “robusthed” i forhold til stress være relevante at undersøge også i forhold til økologisk akvakultur produktion. I dette studie undersøgtes adfærdsmæssige, metabolske og produktions relaterede egenskaber hos juvenile regnbueørreder med forskellig fødesøgnings adfærd. Ny-klækket regnbueørred yngel blev sorteret i forhold til tidspunkt for fødesøgning/swim-up. Den “tidlige”, “midterste” og “sene fraktion” blev undersøgt med hensyn til fysiologisk respons på stress, vækst, stofskifte, sult tolerance, samt potentiale for kompensatorisk vækst. Den ”tidlige” fraktion viste proaktiv adfærd; de var hurtigere tilbage ved overfladen efter at være blevet jaget, viste reduceret kortisol respons efter stress, samt hermed forbundet lavere metabolske omkostninger. Tidspunkt for swim-up var ikke korrelleret med forskelle i hverken standard eller maximum stofskifte, men var derimod korrelleret med højere hvile stofskifte, udtrykt ved signifikant større vægttab ved sult i ”tidlig” gruppe. Vækst rater og foderkonvertering var ikke signifikant forskellige, når fiskene blev holdt sammen under et restriktivt fodrings regime, hvilket indikerer, at ”tidlige swim-up fisk” ikke er i stand til at dominere over foder ressourcerne. Den ”midterste” swim-up gruppe, som udgør majoriteten i en population, syntes at vokse bedst, muligvis fordi de ikke bruger energy på dominerende adfærd som den “tidlige” swim-up fraktion.

EPrint Type:Journal paper
Keywords:Organic, rainbow trout, swim-up, stress coping, metabolism, welfare
Subjects: Animal husbandry > Feeding and growth
Animal husbandry > Health and welfare
Research affiliation: Denmark > Organic RDD 4 > ShelterFish
DOI:10.1016/j.cbpa.2019.01.016
Deposited By: Jokumsen, Senior Advisory Scientist Alfred
ID Code:36307
Deposited On:01 Aug 2019 09:15
Last Modified:01 Aug 2019 09:15
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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