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.
In land-based fish farms, water quality can be controlled to support maximum growth and good feed conversion. Oxygen is an important water quality parameter in aquaculture and the objective of this ...study was to detect the range of oxygen saturations that maximizes growth of juvenile Atlantic cod. The fish (initial body mass 21.9g) were reared at five different levels of oxygen saturation: 65%, 81%, 103%, 121% and 150% of air saturation, for 98days. At oxygen saturation under 100%, the growth of the fish decreased linearly with progressively lower oxygen saturation with the final body mass of fish reared at 65% saturation being 24% lower than that of fish reared at 103% saturation. The final body mass of fish reared at 150% saturation was significantly higher (7%) than that of fish reared at 103% saturation. Feed intake was also affected by oxygen saturation and was proportional to growth while the feed conversion ratio was not significantly affected by oxygen levels. The results suggest that oxygen saturation of at least 100% is required to obtain maximum growth of juvenile Atlantic cod.
•Growth rate of Atlantic cod is progressively reduced below 100% oxygen saturation.•Hypoxia (61 and 83% saturation) leads to progressively lower growth rates and feed intake.•It is suggested, that Atlantic cod require higher oxygen saturation for maximum growth than indicated in earlier studies.
To study the isolated and combined effects of unionised ammonia (UIA-N) and CO2 in water on juvenile Atlantic cod, fish were exposed to four different treatments: moderate levels of CO2 (10mgL−1); ...moderate levels of NH3 (0.06mgL−1 UIA-N); a combination of CO2 (10mgL−1) and NH3 (0.06mgL−1 UIAN) and a control treatment without added CO2 or NH3, for 41days. The final weight of the groups exposed to either CO2 or NH3 were not significantly different from the control group, where 22% weight gain was observed during the course of the 41-day exposure time. Minor differences in SGR were observed during the first growth period, but not later, between the control and the CO2 and NH3 groups, suggest that the fish were able to adapt to the conditions over time. However, no weight gain and lower feed intake was observed in the group exposed to both CO2 and NH3. To create identical UIA-N for the NH3 and CO2+NH3 groups it was necessary to double the TAN for the latter group due to lower pH resulting in doubling of NH4+. It is suggested, that the high NH4+ to which the CO2+NH3 group was exposed may have caused the reduced growth.
•Moderate levels of CO2 or NH3 have little or no effect on the growth of Atlantic cod when applied separately.•When applied in combination these levels can suppress the growth of Atlantic cod.
Atlantic salmon (Salmo salar) is one of the worlds most domesticated fish. As production volumes increase, access to high quality and sustainable protein sources for formulated feeds of this ...carnivorous fish is required. Soybean meal (SBM) and soy-derived proteins are the dominant protein sources in commercial aquafeeds due to their low-cost, availability and favorable amino acid profile. However, for Atlantic salmon, the inclusion of soybean meal (SBM), and soy protein concentrate (SPC) in certain combinations can impact gut health, which has consequences for immunity and welfare, limiting the use of soy products in salmonid feeds. This study sought to address this challenge by evaluating two gut health-targeted enhancements of SBM for inclusion in freshwater phase salmon diets: enzyme pre-treatment (ETS), and addition of fructose oligosaccharide (USP). These were compared with untreated soybean meal (US) and fish meal (FM). This study took a multi-disciplinary approach, investigating the effect on growth performance, gut microbiome, and behaviors relevant to welfare in aquaculture. This study suggests that both enhancements of SBM provide benefits for growth performance compared with conventional SBM. Both SBM treatments altered fish gut microbiomes and in the case of ETS, increased the presence of the lactic acid bacteria Enterococcus. For the first time, the effects of marine protein sources and plant protein sources on the coping style of salmon were demonstrated. Fish fed SBM showed a tendency for more reactive behavior compared with those fed the FM-based control. All fish had a similar low response to elicited stress, although ETS-fed fish responded more actively than US-fed fish for a single swimming measure. Furthermore, SBM-fed fish displayed lower repeatability of behavior, which may indicate diminished welfare for intensively farmed fish. The implications of these findings for commercial salmonid aquaculture are discussed.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Summary Background & aims Validation of simple methods for estimating energy and protein intakes in hospital wards are rarely reported in the literature. The aim was to validate a plate diagram sheet ...for estimation of energy and protein intakes of patients by comparison with weighed food records. Methods Subjects were inpatients at the Cardio Thoracic ward, Landspitali National University Hospital, Reykjavik, Iceland ( N = 73). The ward personnel used a plate diagram sheet to record the proportion (0%, 25%, 50%, 100%) of meals consumed by each subjects, for three days. Weighed food records where used as a reference method. Results On average the plate diagram sheet overestimated energy intake by 45 kcal/day (1119 ± 353 kcal/day versus 1074 ± 360 kcal/day, p = 0.008). Estimation of protein intake was not significantly different between the two methods (50.2 ± 16.4 g/day versus 48.7 ± 17.7 g/day, p = 0.123). By analysing only the meals where ≤50% of the served meals were consumed, according to the plate diagram recording, a slight underestimation was observed. Conclusion A plate diagram sheet can be used to estimate energy and protein intakes with fair accuracy in hospitalized patients, especially at the group level. Importantly, the plate diagram sheet did not overestimate intakes in patients with a low food intake.
The bacterium Aeromonas salmonicida ssp. achromogenes (Asa) causes atypical furunculosis in salmonids that may lead to extensive financial losses in intensive fish farming. The commercially available ...vaccine commonly used against the ssp. achromogenes in the production of Arctic charr in Iceland has been developed for Atlantic salmon (Salmon salar) against the subspecies salmonicida which causes typical furunculosis, but it has insufficient efficacy in Arctic charr. In response to this, a novel vaccine against Asa in Arctic charr was developed in cooperation with Spanish vaccine company; HIPRA, and the antibody response of Arctic charr against Asa investigated using enzyme-linked immunosorbent assay. Fish used for testing were vaccinated using the novel, monovalent autogenous experimental vaccine and a commercially available vaccine Alpha Ject® 3000 developed for Atlantic salmon that was used as a comparison. The study was conducted in commercial production units where the fish were continually exposed to natural outbreaks of atypical furunculosis. Blood samples were collected from the fish prior to vaccination and thereafter at approximately ten-week intervals in each production unit throughout the production period until the fish reached harvesting size. Fish growth and mortality was recorded throughout the study. The results indicated that both vaccines induced antibody response in fish against Asa antigens and that antibody titers obtained during the first weeks following vaccination were maintained throughout the production period. However, significantly higher antibody titers were observed in fish vaccinated with the experimental novel vaccine and fish mortality was significantly lower in production units containing fish vaccinated with the novel vaccine in comparison to the Alpha Ject 3000® vaccine. These results suggest that the novel vaccine may be a promising candidate for protective immunity against atypical furunculosis caused by Asa in Arctic charr.
•The specific antibody responses in Arctic charr against Aeromonas salmonicida ssp. achromogenes were analyzed using ELISA.•A novel experimental vaccine developed for Arctic charr and a commercial vaccine developed for Atlantic salmon were compared.•The novel experimental vaccine induced a higher specific antibody response and with more extended duration.•Significantly reduced fish mortality was observed in the group vaccinated using the experimental vaccine.
Three feeding trials were conducted to estimate the minimum protein requirements for maximum growth of Atlantic cod (initial size 37-600 g). The diets in each trial were near iso-energetic and ...contained 47-64% crude protein (CP) in dry matter for small fish while diets for larger fish contained 36-57% CP. There was no significant difference in the final weight of small fish (90-130 g) fed different levels of CP. However, the specific growth rate (SGR) of fish fed 59% and 64% CP (0.9% day⁻¹) was significantly higher than that of fish fed either 47% or 48% CP (0.5-0.7% day⁻¹). The hepato-somatic index (HSI) increased progressively with decreased CP and the feed conversion ratio (FCR) was negatively correlated with CP of the diets. In two trials with larger fish, CP did not significantly affect mean final weight (750-900 g), SGR or FCR. As for the smaller fish, the HSI was negatively correlated with CP and in one of the experiments, the feed intake was also negatively correlated with CP. The feed efficiency tended to be reduced. The results suggest that the protein requirement for maximum growth in Atlantic cod is size dependent: for 40-107 g fish, the minimum CP is 47-52% and for larger fish (400-900 g) it is 36% or lower.
Bacteria dominating the cultivable gut community of overall successful first feeding halibut (
Hippoglossus hippoglossus L.) larvae were tested for their
in vitro growth inhibition activity against ...selected fish pathogenic bacteria and isolates dominating the cultivable gut community of larvae with an overall poor success. A mixture containing equal numbers of three isolates was selected for the treatment of halibut eggs through repeated bathing, and larvae through grazing of live prey in a mixture of the selected isolates prior to offering to larvae. The isolates were found as a part of the dominating bacterial community of treated eggs and treatment was not found to affect egg survival. Improved larval survival was observed as a result of offering bacteria-treated live prey to larvae, and improved larval growth was observed in one of the two experiments that were carried out in commercial size production units. The bacterial community structure of the live prey, analysed using PCR and denaturing gradient gel electrophoresis, was only partly reflected in larvae after one week in feeding. A successful colonization of fertilized eggs by the isolates used for treatment entails the possibility to establish a favourable bacterial environment already prior to hatching.
The high mortality commonly observed during the early life stages of intensively reared halibut (
Hippoglossus hippoglossus L) is believed to be caused by e.g. opportunistic bacteria. However, the ...impact of particular bacterial species is poorly defined and still remains disputable. The study describes the bacterial diversity in the gastrointestinal tract of halibut larvae in a large number of incubators at a commercial production site. The overall success of larvae was found to be highly variable and analysis of the gut microbiota revealed high variation of the cultivable part as well as the bacterial community of surface sterilised larvae analysed by denaturing gradient gel electrophoresis (DGGE) of PCR amplified 16s rDNA products. Analysis of the bacterial community of unfed yolk sac larvae revealed higher diversity than previously reported, with
Marinomonas,
Marinobacter,
Aeromonas and
Shewanella dominating the community structure. There are indications that
Marinomonas is found only in the overall most successful first feeding larvae of the period where the
Vibrio group dominated the bacterial community together with
Shewanella.
Vibrio wodanis was identified as a part of the bacterial community of feeding larvae that yielded the poorest overall success of the period. α
-Proteobacteria, not previously reported in halibut, were also found as a part of the bacterial community of first feeding larvae. The diverse bacterial community was only partly reflected in the cultivable part which, however, may reflect the dominating bacterial groups of the highly heterogeneous bacterial community of larvae in the production system as a whole. The bacterial community of the
Artemia was found to be highly variable in different samples collected through the period. Only a small part of the different groups observed in the bacterial community of surface sterilised larvae was reflected in the cultivable part which was dominated by highly variable groups in different samples of
Artemia. Also, the numbers of cultivable bacteria were found to positively correlate with jaw deformation of unfed yolk sac larvae as well as incomplete metamorphosis of feeding larvae.
This article discusses the discrepancy between formal rights to full social inclusion and the lived experiences of young adults with learning difficulties. It draws on inclusive life history research ...in Iceland and employs intersectional theory to study the social participation of young adults with learning difficulties. In an attempt to understand the complex political, economic and ideological forces that hinder the actualisation of their formal rights the intersection of disability, class, gender and religion in the production and reproduction of existing social hierarchies is examined. The article demonstrates how the research collaborators resisted their devalued social construction and attempted to create and affirm themselves as competent social actors.
