Genetic improvement of feed conversion ratio via indirect selection against lipid deposition in farmed rainbow trout (Oncorhynchus mykiss Walbaum)

The research leading to these results has received funding from the European Union's Seventh Framework Programme (KBBE.2013.1.2-10) under grant agreement n° 613611 FISHBOOST. Moreover, the original data collection was supported by the European Union, Project PROGRESS Q5RS-2001-00994. The staff at Tervo station, Ossi Ritola and Tuija Paananen, are highly acknowledged for fish management. A. Ka., A. Ki., S. M., D. H. and K. R. designed research and wrote the paper; A.Ka analyzed the data and had primary responsibility for the final content. All authors have read and approved the manuscript. The authors declare no conflicts of interest.Peer reviewedPostprintPublisher PD

Evaluation of Nutritional Composition of Pure Filamentous Fungal Biomass as a Novel Ingredient for Fish Feed

The rapid growth of aquaculture and the lack of fish meal demand new sustainable ingredients. Although fungal biomass is found to be a promising sustainable fish feed supplementation candidate, the characteristics of this protein-rich source are closely influenced by the quality of the applied growth medium. In this work, the nutritional properties of pure filamentous fungal biomass provided from the cultivation of Aspergillus oryzae, Neurospora intermedia and Rhzopus oryzae were evaluated to assess their potential as alternative novel protein sources in fish feed. In this regard, fungal biomass yields of up to 0.19 ± 0.005 (g dry biomass/g substrate glucose) were obtained during submerged cultivation of fungal strains. The pure fungal biomass acquired could contain significant amounts of protein up to 62.2 ± 1.2% (w/w). The obtained protein had a high quality with notable inclusion of essential amino acids such as lysine, arginine, methionine and threonine with comparable concentrations to those of fish meal. Fungal biomass is mainly considered as protein source, however, entitlement of 6.9 ± 0.5, 4.0 ± 0.7 and 17.2 ± 1.1% (w/w) of lipids and ratio of polyunsaturated fatty acids (PUFA) to saturated fatty acids (SFA) of 1.37:1, 1.74:1 and 1.47:1 in A. oryzae, N. intermedia and R. oryzae, respectively, signal health benefits for the fish. Considering the results, protein-rich pure fungal biomass with amino acid composition is greatly compatible with fish meal, and contains essential nutrients such as fatty acids and minerals. This pure biomass constitutes a promising sustainable alternative supplement to be introduced in fish feed industry

Attraction and repulsion of mobile wild organisms to finfish and shellfish aquaculture: a review

Knowledge of aquaculture–environment interactions is essential for the development of a sustainable aquaculture industry and efficient marine spatial planning. The effects of fish and shellfish farming on sessile wild populations, particularly infauna, have been studied intensively. Mobile fauna, including crustaceans, fish, birds and marine mammals, also interact with aquaculture operations, but the interactions are more complex and these animals may be attracted to (attraction) or show an aversion to (repulsion) farm operations with various degrees of effects. This review outlines the main mechanisms and effects of attraction and repulsion of wild animals to/from marine finfish cage and bivalve aquaculture, with a focus on effects on fisheries-related species. Effects considered in this review include those related to the provision of physical structure (farm infrastructure acting as fish aggregating devices (FADs) or artificial reefs (ARs), the provision of food (e.g. farmed animals, waste feed and faeces, fouling organisms associated with farm structures) and some farm activities (e.g. boating, cleaning). The reviews show that the distribution of mobile organisms associated with farming structures varies over various spatial (vertical and horizontal) and temporal scales (season, feeding time, day/night period). Attraction/repulsion mechanisms have a variety of direct and indirect effects on wild organisms at the level of individuals and populations and may have implication for the management of fisheries species and the ecosystem in the context of marine spatial planning. This review revealed considerable uncertainties regarding the long-term and ecosystem-wide consequences of these interactions. The use of modelling may help better understand consequences, but long-term studies are necessary to better elucidate effects

Coho salmon (Oncorhynchus kisutch) transgenic for a growth hormone gene construct exhibit increased rates of muscle hyperplasia and detectable levels of differential gene expression

Transgenic coho salmon (Oncorhynchus kisutch) containing a growth hormone gene construct were compared with nontransgenic coho salmon in terms of gross anatomy, muscle cellularity, muscle enzyme activity, and differential gene expression. Transgenic fish were found to have significantly higher numbers of small-diameter muscle fibres in both the dorsal and lateral region of the somitic muscle, suggesting that they grow by greater rates of hyperplasia relative to slower growing nontransgenic fish. Higher levels of activity were found for phosphofructokinase and cytochrome oxidase in white muscle of the transgenic fish. This difference indicates a higher glycolytic and aerobic requirement in the muscle of transgenic fish. Subtractive hybridisation of muscle RNA of transgenic fish from control fish provided a library of cDNAs whose expression is upregulated in the transgenic fish. This library contains genes that may be involved in, or related to, both high growth rates and muscle hyperplasia. We have sequenced a number of fragments and have found a preponderance of myosin light chain 2 mRNAs, consistent with a putative high level of expression in the early stages of muscle fibre construction

Dietary Filamentous Fungi and Duration of Feeding Modulates Gut Microbial Composition in Rainbow Trout (Oncorhynchus mykiss)

Changes in gut microbial composition over time in rainbow trout fed differentially processed diets supplemented with the filamentous fungi Neurospora intermedia were investigated in a 30-day feeding trial. Fish were fed a reference diet, non-preconditioned diet (NPD), or preconditioned (heat-treated) diet (PD), with the same inclusion level of N. intermedia in diets NPD and PD. Gut microbiota were analyzed on day 0, 10, 20, and 30. Gut microbial composition was similar for all diets on day 0, but was significantly different at day 10 and day 20. On day 30, the gut again contained similar communities irrespective of diet. The overall gut microbiota for each diet changed over time. Abundance of Peptostreptococcus and Streptococcus was higher in the initial days of feeding in fish fed on commercial diet, while a significant increase in lactic acid bacteria (Lactococcus lactis) was observed on day 30. Feed processing (preconditioning) did not contribute largely in shaping the gut microbiome. These results indicate that dietary manipulation and duration of feeding should be considered when evaluating gut microbial composition in cultured fish. A minimum 30-day feeding trial is suggested for gut microbiome, host and diet interaction studies

Continuous physiological welfare evaluation of European whitefish (Coregonus lavaretus) during common aquaculture practices leading up to slaughter

European whitefish (Coregonus lavaretus) is an aquaculture species with the potential for expanded cultivation in the fresh and brackish waters of Northern Europe. Yet, relatively little species-specific information is available regarding the stress responses and associated welfare implications for this species in captivity. We addressed this knowledge gap by using a combination of implantable heart rate bio-loggers and a range of traditional stress indicators (e.g. haematological parameters and plasma concentrations of cortisol, glucose and ions) to comprehensively evaluate the physiological responses of freely swimming whitefish in captivity, as well as when subjected to aquaculture practices and stressors that commonly occur prior to and during slaughter. Whitefish appeared to recover rapidly from surgery, as resting heart rate decreased within 36 h to stabilize at similar to 25 beats min(-1) for the next 18 days when fish were left relatively undisturbed (i.e. personnel were only present when feeding fish). In contrast with previous studies on farmed rainbow trout and Atlantic salmon, whitefish did not exhibit a clear circadian heart rate rhythm, which may be related to species-specific differences in diurnal locomotor activity. Whitefish also appear to have a well-developed capacity for thermal acclimation of heart rate, as daily resting heart rate did not change during the undisturbed period despite an increase in body temperature from similar to 6.8 to 11.2 degrees C. Following acute stressors such as crowding and transportation, the physiological response of whitefish typically involved transient elevations in heart rate, plasma cortisol and glucose, and red blood cell swelling, while plasma [K+] decreased. In contrast, the heart rate of whitefish plummeted following the combination of brailing (i.e. to haul in fish with a brail/net) and CO2 exposure prior to slaughter, while plasma cortisol, glucose and [Ca2+] significantly increased. An unforeseen finding concerns the substantial and long-lasting physiological stress response observed in whitefish when held in close proximity (i.e. within similar to 10 m) to a rainbow trout net pen, as the mean heart rate of whitefish increased from similar to 32 to 43 beats min(-1) (i.e. an increase of similar to 34%). This may represent an innate physiological response to the threat of predation, which consequently increases the allostatic load and energetic expenditure of whitefish when farmed alongside salmonids. To conclude, this study highlights the importance of performing long-term, species-specific evaluations of freely swimming fish in real aquaculture settings, and provides a platform for further research aiming to determine the welfare implications of simultaneously farming predatory and prey species in close proximity

Fat of lean? : the quantitative genetic basis for selection strategies of muscle and body composition traits in breeding schemes of rainbow trout (Oncorhynchus mykiss)

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