A holistic approach to development of diets for Ballan wrasse (Labrus berggylta) – a new species in aquaculture

Wild wrasses are used for delousing of farmed salmon but increasing demands have prompted the salmon industry to develop cultures of Ballan wrasse. One of the bottlenecks has been nutrition and feed intake in the juvenile phase, while broodstock nutrition is considered critical for production of viable offspring. The present study was aimed at developing functioning ongrowing and broodstock diets for Ballan wrasse. In juveniles the best lengthwise growth was identified at 65% dietary protein, 12% lipid and 16% carbohydrate. To investigate if the requirements for the other nutrients were covered by the diets developed for the species, the nutrient composition in juveniles (whole body) and broodstock (female gonad) were analyzed and compared to the composition in wild fish. We found that the levels of the lipid soluble Vitamins A, K and D were lower in cultured than in wild fish, however, the requirements for these nutrients in Ballan wrasse are not known. Other candidate nutrients for more in-depth investigation are the bone minerals, zinc, taurine and fatty acids

Increasing the levels of the essential trace elements Se, Zn, Cu and Mn in rotifers (Brachionus plicatilis) used as live feed

Rotifers are a common first feeding diet for rearing marine fish larvae. However, the levels of Mn, Cu, Zn, Se and iodine found in rotifers are low and may be insufficient to meet larval fish requirements. This study investigates increasing the concentration of Mn, Cu, Zn, Se and iodine simultaneously in rotifers (Brachionus plicatilis) in both short term enrichments (3 h) or during batch cultures (6 days), using either organically bound or inorganic mineral sources. This study demonstrates that rotifers can simultaneously be produced with Mn, Cu, Zn and Se concentrations up to and higher than the known requirements of fish, while increasing the level of iodine in rotifers was ineffective at the concentrations tested. To produce rotifers with copepod levels of Mn, Cu, Zn and Se, only 6% of a commercial rotifer enrichment diet had to be replaced with organically bound minerals, leaving a large percentage of the rotifer diet free to deliver other important nutrients such as lipid and proteins. Rotifers enriched to copepod mineral levels and stored for 18 h retained 75–110% of their Se, Zn and Mn and 50% of their Cu. Overall, increasing rotifer mineral levels appears to be most effective when the mineral is available in an insoluble and hence ingestible form.publishedVersio

Iodine nutrition and toxicity in Atlantic cod (Gadus morhua) larvae

-Copepods as feed promote better growth and development in marine fish larvae than rotifers. However, unlike rotifers, copepods contain several minerals such as iodine (I), at potentially toxic levels. Iodine is an essential trace element and both under and over supply of I can inhibit the production of the I containing thyroid hormones. It is unknown whether marine fish larvae require copepod levels of I or if mechanisms are present that prevent I toxicity. In this study, larval Atlantic cod (Gadus morhua) were fed rotifers enriched to intermediate (26 mg I kg-1 dry weight; MI group) or copepod (129 mg I kg-1 DW; HI group) I levels and compared to cod larvae fed control rotifers (0.6 mg I kg-1 DW). Larval I concentrations were increased by 3 (MI) and 7 (HI) fold compared to controls during the rotifer feeding period. No differences in growth were observed, but the HI diet increased thyroid follicle colloid to epithelium ratios, and affected the essential element concentrations of larvae compared to the other groups. The thyroid follicle morphology in the HI larvae is typical of colloid goitre, a condition resulting from excessive I intake, even though whole body I levels were below those found previously in copepod fed cod larvae. This is the first observation of dietary induced I toxicity in fish, and suggests I toxicity may be determined to a greater extent by bioavailability and nutrient interactions than by total body I concentrations in fish larvae. Rotifers with 0.6 mg I kg-1 DW appeared sufficient to prevent gross signs of I deficiency in cod larvae reared with continuous water exchange, while modelling of cod larvae versus rotifer I levels suggests that optimum I levels in rotifers for cod larvae is 3.5 mg I kg-1 DW

Online consultations in mental healthcare: Modelling determinants of use and experience based on an international survey study at the onset of the pandemic

Introduction: While online consultations have shown promise to be a means for the effective delivery of high -quality mental healthcare and the first implementations of these digital therapeutic contacts go back nearly two decades, uptake has remained limited over the years. The onset of the COVID-19 pandemic dramatically altered this relative standstill and created a unique turning point, with a massive amount of both professionals and clients having first hands-on experiences with technology in mental healthcare.Objective: The current study aimed to document the uptake of online consultations and explore if specific characteristics of mental health professionals across and beyond Europe could predict this.Methods: An international survey was designed to assess mental health professionals' (initial) experiences with online consultations at the onset of the pandemic: their willingness to make use of them and their prior and current experiences, alongside several personal characteristics. Logistic mixed-effects models were used to identify predictors of the use of online consultations, personal experience with this modality, and the sense of telepresence.Results: A total of 9115 healthcare professionals from 73 countries participated of which about two-thirds used online consultations during the initial COVID-19 outbreak. The current study identifies multiple determinants relating to the use and experience of online consultations, including the professionals' age, experience with the technology before the outbreak, the professional context, and training.Conclusions: Despite strong evidence supporting the relevance of training in digital mental health, this is clearly still lacking. Nevertheless, the COVID-19 pandemic presented a first, and potentially transformative, experience with online consultations for many healthcare professionals. The insights from this study can help supportprofessionals and, importantly, (mental) healthcare organisations to create optimal circumstances for selective and high-quality continued use of online consultations

Increasing the levels of the essential trace elements Se, Zn, Cu and Mn in rotifers (Brachionus plicatilis) used as live feed

Rotifers are a common first feeding diet for rearing marine fish larvae. However, the levels of Mn, Cu, Zn, Se and iodine found in rotifers are low and may be insufficient to meet larval fish requirements. This study investigates increasing the concentration of Mn, Cu, Zn, Se and iodine simultaneously in rotifers (Brachionus plicatilis) in both short term enrichments (3 h) or during batch cultures (6 days), using either organically bound or inorganic mineral sources. This study demonstrates that rotifers can simultaneously be produced with Mn, Cu, Zn and Se concentrations up to and higher than the known requirements of fish, while increasing the level of iodine in rotifers was ineffective at the concentrations tested. To produce rotifers with copepod levels of Mn, Cu, Zn and Se, only 6% of a commercial rotifer enrichment diet had to be replaced with organically bound minerals, leaving a large percentage of the rotifer diet free to deliver other important nutrients such as lipid and proteins. Rotifers enriched to copepod mineral levels and stored for 18 h retained 75–110% of their Se, Zn and Mn and 50% of their Cu. Overall, increasing rotifer mineral levels appears to be most effective when the mineral is available in an insoluble and hence ingestible form

Challenges related to delivery of water soluble nutrients to marine fish larvae. Evaluation of changes in nutritional quality due to production process and leaching from larval diets -with emphasis on protein quality

Marine fish larvae fed formulated diets have suppressed growth and survival compared to larvae fed live feed for the first weeks. Live feed is successfully used in the aquaculture industry, although there are difficulties delivering controllable concentrations of several nutritional compounds. In research, the use of formulated diets is therefore essential to accomplish proper nutritional dose response studies. The focus of this work was to study the properties of a protein cross-linked diet and a heat coagulated diet used for nutritional studies of marine fish larvae. The ability to deliver water soluble nutrients and changes in protein quality due to production processes and exposure to leaching was emphasized. A pancreatic protein in vitro digestibility method, simulating stomachless fish larvae, was used to investigate the digestibility of various live feeds and feed ingredients. The same in vitro model was also used to study the effect of the production processes and the effect of increased inclusion of hydrolyzed protein in compound diets. Both diets showed substantial changes in protein quality due to the production process and exposure to leaching. The protein cross-linked capsules had a nearly complete loss of watersoluble nitrogen (N) during cross-linking and the following washing steps and more than 90 % loss of other water-soluble micronutrients. The protein cross-linking led to a 25 % reduction in in vitro protein digestibility. A large fraction of the soluble N in the feed ingredients was made insoluble by heat denaturation during production of the heat coagulated diet, but the concentrations of peptides and free amino acids (FAA) were not influenced. However, after exposure to leaching for 6 min most of the soluble N fraction was lost and there were no significant difference in concentrations of soluble N between diets with increasing concentration of hydrolyzed protein ranging from 0 % to 45 % of total protein. There were no significant differences in in vitro digestibility between the four diets with increasing concentration of hydrolyzed protein. However, the leached diets showed significantly reduced digestibility compared to the diets that had not been exposed to leaching. In conclusion, neither the protein cross-linked nor the heat coagulated diet may be suitable for the delivery of water-soluble nutrients to marine fish larvae. The protein in vitro digestibility of the protein cross-linked diet, heat coagulated diets and a commercial larval diet (53 – 73 %) were lower than frozen live feed (84 – 87 %). The digestibility of the soluble N fractions was similar for the marine meals and the live feed and higher than the respective insoluble protein fractions. However, the live feed contained 54-67 % soluble N in comparison to the marine meals that only contained 11-17 % soluble N. In the search for other possible diets to deliver soluble nutrients, lipid spray beads (LSB) were investigated. LSB, as part of complex particles, has been an interesting candidate for delivering soluble nutrients with a high retention efficiency, although the fatty acid profile of the LSB have made them inappropriate when delivered in large quantities. LSB with an improved fatty acid profile were developed by inclusion of high concentrations of phospholipids. Due to the hydrophilic behavior of phospholipids, the LSB dispersed in water and could therefore be used to deliver water soluble micronutrients to live feed. The riboflavin content of Artemia was increased from 55 ± 0.6 mg kg-1 (dw) to 329 ± 62 mg kg-1 (dw) after 1 h enrichment. There is still a severe leaching rate of highly soluble nutrients and the LSB might therefore not be able to deliver nutrients needed in large quantities such as FAA and peptides. However, for nutrients needed in small quantities, the LSB seems to be a promising tool

Evaluation of changes in nutrient composition during production of cross-linked protein microencapsulated diets for marine fish larvae and suspension feeders

8 páginas, 1 figura, 5 tablas.Cross-linked protein capsules as a vehicle for delivery of nutrients to marine fish larvae and marine suspension feeders were investigated. The effects of the production process on both qualitative and quantitative changes in protein, lipid and micronutrient concentrations were evaluated. There were no changes in lipid concentration and only minor (but significant) differences in crude protein concentrations as a result of the encapsulation process. However, there was nearly a complete loss of water-soluble nitrogen during capsule production - almost 100% of the water-soluble protein was cross-linked and made insoluble and 79% of the TCA-soluble N was lost. Peptides and free amino acids were lost during the capsule washing stages, but except for a 100% loss of taurine, small changes in the amino acid profile were observed. There was more than 90% loss of water-soluble micronutrients such as thiamin, vitamin C and zinc during capsule production, and only minor increase in concentration of thiamin and zinc in the diet by increasing the levels of these minerals and vitamins were possible. The fat-soluble vitamin E was not affected by the production process and can be delivered at controlled concentrations, but vitamin A had loss ranging from 4-57% with increased inclusion of vitamin A. With the existing production protocol, the results suggest that cross-linked protein capsules are not suitable for the delivery of water-soluble nutrients to fish larvae and marine suspension feeders.This work was part of a project financed by the Norwegian Research Council (Project no 14768/120) and Spanish MCYT (Project AGL2004-06669-C02-01).Peer reviewe

Iodine nutrition and toxicity in Atlantic cod (Gadus morhua) larvae

Copepods as feed promote better growth and development in marine fish larvae than rotifers. However, unlike rotifers, copepods contain several minerals such as iodine (I), at potentially toxic levels. Iodine is an essential trace element and both under and over supply of I can inhibit the production of the I containing thyroid hormones. It is unknown whether marine fish larvae require copepod levels of I or if mechanisms are present that prevent I toxicity. In this study, larval Atlantic cod (Gadus morhua) were fed rotifers enriched to intermediate (26 mg I kg-1 dry weight; MI group) or copepod (129 mg I kg-1 DW; HI group) I levels and compared to cod larvae fed control rotifers (0.6 mg I kg-1 DW). Larval I concentrations were increased by 3 (MI) and 7 (HI) fold compared to controls during the rotifer feeding period. No differences in growth were observed, but the HI diet increased thyroid follicle colloid to epithelium ratios, and affected the essential element concentrations of larvae compared to the other groups. The thyroid follicle morphology in the HI larvae is typical of colloid goitre, a condition resulting from excessive I intake, even though whole body I levels were below those found previously in copepod fed cod larvae. This is the first observation of dietary induced I toxicity in fish, and suggests I toxicity may be determined to a greater extent by bioavailability and nutrient interactions than by total body I concentrations in fish larvae. Rotifers with 0.6 mg I kg-1 DW appeared sufficient to prevent gross signs of I deficiency in cod larvae reared with continuous water exchange, while modelling of cod larvae versus rotifer I levels suggests that optimum I levels in rotifers for cod larvae is 3.5 mg I kg-1 DW