Adaptive capacities from survival to stress responses of two isogenic lines of rainbow trout fed a plant-based diet

Abstract

The composition of feed for farmed salmonids has strongly evolved during the last decades due to the substitution of fishery-derived fish oil and fishmeal by ingredients of plant origin. Little information is available regarding the effects of this transition on adaptive capacities in fish. Two rainbow trout isogenic lines, known for their divergent ability to grow on a plant-based diet (PBD), were fed for seven months from first feeding either a fully PBD or a control marine-resources diet and were compared for their growing and survival capacities over time and their behavioral and stress responses at similar sizes but different ages. Although fish displayed similar appetitive behaviour, the two lines were highly affected by the PBD translated in decreased growth and apathetic behaviour, but also stronger stress responses displayed by stronger cortisol increases and more stress-related behaviour when isolated. The two lines were found to be similarly sensitive to a PBD for the assessed stress-related parameters, but one line displayed a lower survival during the early rearing period. Overall, these results suggest that a PBD supplied to fish from the alevin stage has strong effects on physiological and behavioural parameters, with possible impairment of fish welfare, but also genome-dependent survival.

Growth, feed utilization and metabolic responses of three gibel carp (Carassius gibelio) strains to fishmeal and plant protein-based diets

“…Interestingly, the response to different protein sources was affected by the genotype of gibel carp as observed in some other fishes (Dupont‐Nivet et al, ; Geay et al, ; Sadoul et al, ).…”

Measuring cortisol, the major stress hormone in fishes

“…In addition, food intake can affect cortisol synthesis, with fasted animals producing generally more cortisol than fed conspecifics (Barcellos et al, ; Barton et al, ). Diet composition can also influence the ability to respond to a stressor (Sadoul et al, ). Finally, the social status of the animal can be crucial, as subordinate and dominant individuals generally display both divergent basal cortisol levels and responsiveness to other superimposed stressors (Doyon et al, ; Earley et al, ; Jeffrey et al, ; Øverli et al, ).…”

“…In a context of global change it is, for example, increasingly applied to gauge human‐induced rapid environmental change in different contexts: polluted areas (Grassie et al, ), habitat degradation (Jeffrey et al, ), exposure to tourism (Geffroy et al, ) or global warming (Beldade et al, ). In aquaculture, effects of changes in rearing conditions on cortisol titres have been intensively investigated, notably as related to the type of feed supplied (Sadoul et al, ), effects of water recirculation (Colson et al, ), or stocking density (McKenzie et al, ; Vijayan & Leatherland, ). Recently, a desire to measure cortisol without stressing animals has led to the development of non‐invasive methods to collect and measure the hormone (Huntingford et al, ; Mormède et al, ; Stevens et al, ).…”

Maternal temperature exposure impairs emotional and cognitive responses and triggers dysregulation of neurodevelopment genes in fish

“…The aim of this study was to thoroughly characterize the impact of high temperature exposure of female rainbow trout ( Oncorhynchus mykiss ) during the reproductive season on offspring emotional and cognitive phenotypes, using specific behavioural tests previously validated in the laboratory (Colson et al, 2015a; Poisson et al, 2017; Sadoul et al, 2016). We also aimed at deciphering the molecular mechanisms mediating such intergenerational effects by analysing genome-wide gene expression in eggs and developing embryos following maternal exposure to high temperature.…”