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- Kiessling, Anders, et al.
(författare)
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Alternative protein sources for fish, not competing with the human food demand evaluated by traditional and novel approaches
- 2016
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- At present, most alternative feed sources in fish is since long known in terrestrial animals. However, in a longer time frame this is questionable from a food security perspective, as these sources often are of human food quality. This is an argument rapidly growing in importance. Microbes, insects and products from other forms of extractive aquaculture are of major interest considering their growth potential, nutritional profile, probiotic qualities and ability to use simple resources as substrates. However, with a transition towards a circular economy, substrates that produce such feed ingredients will to a higher degree be based on waste and by-products. This development will demand novel approach in nutrition research in order to understand non-intuitive positive and negative effects in the fish gut biota, immune response, metabolism, welfare and product quality/safety. We will present our ongoing work, concerning physiological implications of alternative protein sources using in situ experimental technologies, such as cannulation and repeated tissue sampling. This work also combines advanced analytic methods of metabolomics and gut microbiota using amplicon next generation sequencing that targets 16S rDNA for bacterial identification. Data on post-prandial plasma AA profile, hematological parameters and erythrocyte indices will be presented together with data concerning the interaction between diet and stress in fish where fishmeal has been replaced by yeast up to 60%. Also, data concerning changes of the microbiota of fish given fungal mycelium-, yeast-, insect- (if ready) and mussel meal will be presented, including comparison between nutrient efficiency of feed given in clear or “green” water environments. Finally, experiments concerning yeast as biological barrier to prions, i.e. food safety, will be discussed. In all, an overall picture of one possible future development in fish nutrition will be painted with a focus on the use of novel feed stuffs in circular food production systems.
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| 4. |
- Sen, Sorphea, et al.
(författare)
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Effect of dietary replacement of fishmeal with spent brewer’s yeast on growth performance of Asian seabass (Lates calcarifer) in Cambodian coastal aquaculture.
- 2019
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Ingår i: Livestock Research For Rural Development. - 0121-3784. ; 31
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Tidskriftsartikel (refereegranskat)abstract
- Coastal Asian seabass farming is an emerging industry in Cambodia, but most farmers depend upon trash fish to feed seabass due to the high cost of formulated diets, with inherent biosecurity and sustainability problems. Use of locally sourced, low-cost ingredients would overcome the major cost obstacle to integration of dry, formulated diets into Cambodian seabass aquaculture. We conducted two feed trials, one in tanks and one in hapas, to evaluate replacement of fishmeal in dry formulated diets with spent yeast sourced from a local brewery. Replacement of fishmeal with dry brewer’s yeast at 0%, 20%, 37% and 47% did not significantly affect performance in terms of growth and feed conversion in either culture system. Brewer’s yeast can thus be an affordable, locally sourced replacement for fishmeal in formulated diets for farmed seabass in Cambodia.
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| 5. |
- Sen, Sorphea
(författare)
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Evaluation on brewery yeast and insect meal (black soldier fly and cricket meal) to replace trash fish in the diet for Asian seabass (Lates calcarifer) in Cambodia
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sustainable development of marine aquaculture in Cambodia was studied in this thesis, using Asian seabass as the target species. An initial survey mapped current production practices, geographical occurrence and production volumes of Asian seabass farming in coastline provinces in Cambodia (Preah Sihanoukvill, Kampot and Koh Kong). Tolerance to different salinities and alternative local feed sources were then assessed in studies conducted at Marine Aquaculture Research and Development Centre (MARDeC) in Preah Sihanoukvill and at An Giang University, Vietnam. A small digestibility study of all feed sources tested was also conducted at An Giang University. The survey revealed that fish farming was conducted both in marine and brackish water and that the most common feed used was trash fish. Commercial dry pellets were only used when fish were reared in ponds or for small fish, mainly due to high costs, which were a major constraint preventing farmers from changing from feeding trash fish to pellets. A series of experiments including two life stages of Asian seabass (fry and fingerlings) and graded levels of salinity found no significant differences in weight gain (WG, g), feed conversion ratio (FCR), daily weight gain (DWG, g day-1), specific growth rate (SGR) or condition factor (CF) in fry or fingerlings at different levels of salinity (fry treatments: 0, 5, 10 and 20 practical salinity units (psu); fingerling treatments 10, 20 and 30 psu). Experiments on including graded levels of brewer's yeast to replace dietary fishmeal (at 0, 20, 37 and 47 % based on dry matter, denote BY0, BY1, BY2 and BY3), performed in hapa and tanks, indicated only slight, non-significant differences in survival rate (SR, %). Body weight (BW, g) and DWG decreased towards the end of the experimental period, but with no differences between treatments (p=0.89 and p=0.26). However, the fish tended to display increased feed intake (p=0.61 and p=0.93) and FCR (p=0.54 and p=0.33) in hapa and tank respectively with higher level of yeast inclusion, indicating that fish on high levels of yeast need to eat more feed per unit weight gain. In the tank experiment, there was no significant difference in CF or SR, but BW increased around four-fold in all treatments. The main difference between the tank and hapa experiments was in FCR, possibly due to feed losses through the net in the hapa base, while the fish in tanks could feed on the bottom. A study on using cricket and black soldier fly (BSF) full-fat meal to replace fishmeal in the diet of Asian seabass revealed two major problems: i) The fish were accustomed to floating pellets and the experimental feed was sinking pellets, which reduced feed intake in all treatments (including control) and resulted in fish weight only doubling. Fish kept on floating commercial pellets in a parallel system performed well, with a four-fold weight increase. A longer adaptation period of the fish to sinking pellets could improve the outcome. ii) The fishmeal used as high-quality protein control was spiked with non- protein nitrogen, indicating that analysis discriminating between protein and non-protein nitrogen should be performed before feed formulation. Overall, the results indicated that both BSF and cricket full-fat meal are potential replacers of fishmeal, and thus also of trash fish, in the diet of Asian seabass. Digestibility analysis confirmed their feed value.
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