Search

Arctic charr has emerged as a valuable candidate for diversifying commercial salmonid products for human consumption. The selective process is ongoing and the species has not been fully domesticated yet. Considering these factors, the impact of fish meal replacement on Arctic charr may differ from that observed in other farmed salmonids. The aim of this multidiciplinary study was to determine whether enhancements to SBM (enzyme pre-treatment and prebiotic addition) facilitate beneficial changes in the growth performance, gut microbiome, and behavior of Arctic charr. The results show that juvenile Arctic charr can tolerate relatively high inclusion levels (25 %) of soybean when supplemented with a prebiotic. However, enzyme pre-treatment of SBM had no beneficial effect on this species. The gut microbiota, mainly consisting of one dominant taxon, Mycoplasma sp., did not appear to be influenced by feed-related bacterial remnants or by the type of feed applied. Behavioral differences and similarities were observed in fish fed different diets. High consistency in the exploration trait was noted, with no impact of diet treatment on its mean value. A response to light stress on swimming activity occurred, regardless of diet treatment. Fish fed the untreated soybean diet exhibited greater boldness, while those fed the enzyme pre-treated diet showed high consistency in boldness. A negative correlation between boldness and growth performance was identified; however, no relationship was found between exploration and growth performance, nor was there a boldness-exploration syndrome in fish fed any of the diet treatments. These differences could not be attributed to variations in the gut microbiome, but other mechanisms that remain to be elucidated might be involved. Further research is needed on the impact of dietary proteins on the behavior and welfare of Arctic charr to optimize existing and new protein sources. • Impact of enhancements to soybean meal is assessed on Arctic charr. • Traits such as growth, gut microbiome and behavior are examined. • High inclusion levels (25 %) of soybean, when supplemented with a prebiotic, could be successfully used. • Microbiota does not appear to be influenced by the diets. • Behavior consistency and mean value vary according to diets. [ABSTRACT FROM AUTHOR]

The evaluation of new diet composition is commonly achieved by performing time-consuming growth trials, which may negatively impact the welfare of a large number of fish if the feed is not accepted. Instead, the fish's behavioural responses to a new diet composition can be used as a first step in the evaluation of new diet composition. The taste acceptance of a new diet by Arctic charr ( Salvelinus alpinus ) was evaluated over 16 days based on the self-selection of a test diet and a control diet. The test diet contained ingredients from the nutrient-enriched Baltic Sea, and it is hoped that this diet can contribute nutrients to the nutrient-poor waters in northern Sweden in which Arctic charr are farmed. The main ingredients in the test feed were blue mussel meat ( Mytilus edulis ), meat from sprat ( Sprattus sprattus ) and herring ( Clupea harengus ), baker's yeast ( Saccharomyces cerevisiae ), fish oil and regionally produced rapeseed oil. Individual fish ( n = 15) were allowed to choose between abundances of both the test diet and a fishmeal based control diet that mimicked a standard feed for Arctic charr. After only a few days, the fish demonstrated a significant preference for the Baltic Sea test feed. These results may depend on betaine, which was found at concentrations that were four times higher in the test feed than in the control feed. Betaine is a known attractant for many fish species and is abundant in marine animals, such as mussels. Thus, the test diet can be evaluated further without additional taste stimulants before the new feed formula can be used commercially to ensure fish welfare, the product quality and the economic feasibility of the new formula. [ABSTRACT FROM AUTHOR]

Behavioural traits have been shown to have implications in fish welfare and growth performances in aquaculture. If several studies have demonstrated the existence of repeatable and heritable behavioural traits (i.e., animal personality), the methodology to assess personality in fishes is often carried out in solitary context, which appears to somewhat limit their use from a selective breeding perspective because these tests are too time consuming. To address this drawback, group-based tests have been developed. In Nordic country, Arctic charr (Salvelinus alpinus) is widely used in aquaculture, but no selection effort on behavioural traits has yet been carried out. Specifically, in this study we examined if risk-taking behaviour was repeatable and correlated in group and solitary context and if the early influences of physical environment affect the among-individual variation of behavioural trait across time in order to verify whether a group risk-taking test could be used as a selective breeding tool. Here, we found that in both contexts and treatments, the risk-taking behaviour was repeatable across 7 days. However, no cross-context consistency was found between group and solitary, which indicates that individual Arctic charr express different behavioural trait in group and solitary. • Risk-taking behaviour was assessed in the Arctic charr. • Fish were raised in plain versus enriched environments. • Risk-taking were tested in solitary versus group contexts. • Risk-taking behaviour was repeatable across 7 days in both contexts. • No consistency was found between the solitaryand groupcontexts. [ABSTRACT FROM AUTHOR]

Abstract: Domestication and selection to enhance growth of animals is likely to affect social behaviour. Aggression may increase or decrease. A 4-generation selection programme on the salmonid species Arctic charr (Salvelinus alpinus L.) based on a well-defined population origin has made it possible to compare the social behaviour of its progeny with progeny from wild parents of the same population, thus excluding the effects of population differences. During 5 months, the within-group growth variation and specific, defined behaviour parameters were observed and analysed under experimental conditions where dominance hierarchies are promoted. In such conditions, which are opposite from farming conditions created to reduce dominance hierarchies, there was no difference in mean growth rate during the observation period and no difference in the social structure (number of dominant, subdominant and subordinate individuals) in the groups. Also, the level of within group aggression did not appear significantly different between level of domestication when observed between or during feeding periods. However, there was a significantly larger growth variation in the progeny of wild parents compared to the selected progeny. Also, the level of aggression increased significantly only in the groups with a selected origin during feeding events compared to periods in-between feeding. Individuals in the wild origin groups showed a significantly higher level of a passive low-profile behaviour compared to the selected origin groups. These differences suggest that selection for fast growth in farming conditions reduces the frequency of subordinate individual behaviour resulting in a smaller intra specific difference in growth in farm strains. [Copyright &y& Elsevier]