C Keating1,2, M Bolton-Warberg3, J Hinchcliffe4, R Davies5, S Whelan3, A H L Wan6,7, R D Fitzgerald3, S J Davies8, U Z Ijaz9, C J Smith10,11. 1. Department of Microbiology, School of Natural Sciences, National University of Ireland Galway, Galway, H91 TK33, Ireland. ciara.keating@glasgow.ac.uk. 2. Water and Environment Group, Infrastructure and Environment Division, James Watt School of Engineering, University of Glasgow, Glasgow, G12 8LT, UK. ciara.keating@glasgow.ac.uk. 3. Carna Research Station, Ryan Institute, National University of Ireland Galway, Carna, Co, Galway, H91 V8Y1, Ireland. 4. Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden. 5. AquaBioTech Group, Central Complex, Naggar Street, Targa Gap, Mosta, G.C, MST 1761, Malta. 6. Irish Seaweed Research Group, Ryan Institute and School of Natural Sciences, National University of Ireland Galway, Galway, H91 TK33, Ireland. 7. Aquaculture Nutrition and Aquafeed Research Unit, Carna Research Station, Ryan Institute and School of Natural Sciences, National University of Ireland Galway, Carna, Co, Galway, H91 V8Y1, Ireland. 8. Department of Animal Production, Welfare and Veterinary Science, Harper Adams University, Newport, Shropshire, TF10 8NB, UK. 9. Water and Environment Group, Infrastructure and Environment Division, James Watt School of Engineering, University of Glasgow, Glasgow, G12 8LT, UK. umer.ijaz@glasgow.ac.uk. 10. Department of Microbiology, School of Natural Sciences, National University of Ireland Galway, Galway, H91 TK33, Ireland. cindy.smith@glasgow.ac.uk. 11. Water and Environment Group, Infrastructure and Environment Division, James Watt School of Engineering, University of Glasgow, Glasgow, G12 8LT, UK. cindy.smith@glasgow.ac.uk.
Abstract
BACKGROUND: Aquaculture successfully meets global food demands for many fish species. However, aquaculture production of Atlantic cod (Gadus morhua) is just 2.5% of total market production. For cod farming to be a viable economic venture specific challenges on how to increase growth, health and farming productivity need to be addressed. Feed ingredients play a key role here. Macroalgae (seaweeds) have been suggested as a functional feed supplement with both health and economic benefits for terrestrial farmed animals and fish. The impact of such dietary supplements to cod gut integrity and microbiota, which contribute to overall fish robustness is unknown. The objective of this study was to supplement the diet of juvenile Atlantic cod with macroalgae and determine the impacts on fish condition and growth, gut morphology and hindgut microbiota composition (16S rRNA amplicon sequencing). Fish were fed one of three diets: control (no macroalgal inclusion), 10% inclusion of either egg wrack (Ascophyllum nodosum) or sea lettuce (Ulva rigida) macroalgae in a 12-week trial. RESULTS: The results demonstrated there was no significant difference in fish condition, gut morphology or hindgut microbiota between the U. rigida supplemented fish group and the control group at any time-point. This trend was not observed with the A. nodosum treatment. Fish within this group were further categorised as either 'Normal' or 'Lower Growth'. 'Lower Growth' individuals found the diet unpalatable resulting in reduced weight and condition factor combined with an altered gut morphology and microbiome relative to the other treatments. Excluding this group, our results show that the hindgut microbiota was largely driven by temporal pressures with the microbial communities becoming more similar over time irrespective of dietary treatment. The core microbiome at the final time-point consisted of the orders Vibrionales (Vibrio and Photobacterium), Bacteroidales (Bacteroidetes and Macellibacteroides) and Clostridiales (Lachnoclostridium). CONCLUSIONS: Our study indicates that U. rigida macroalgae can be supplemented at 10% inclusion levels in the diet of juvenile farmed Atlantic cod without any impact on fish condition or hindgut microbial community structure. We also conclude that 10% dietary inclusion of A. nodosum is not a suitable feed supplement in a farmed cod diet.
BACKGROUND: Aquaculture successfully meets global food demands for many fish species. However, aquaculture production of Atlantic cod (Gadus morhua) is just 2.5% of total market production. For cod farming to be a viable economic venture specific challenges on how to increase growth, health and farming productivity need to be addressed. Feed ingredients play a key role here. Macroalgae (seaweeds) have been suggested as a functional feed supplement with both health and economic benefits for terrestrial farmed animals and fish. The impact of such dietary supplements to cod gut integrity and microbiota, which contribute to overall fish robustness is unknown. The objective of this study was to supplement the diet of juvenile Atlantic cod with macroalgae and determine the impacts on fish condition and growth, gut morphology and hindgut microbiota composition (16S rRNA amplicon sequencing). Fish were fed one of three diets: control (no macroalgal inclusion), 10% inclusion of either egg wrack (Ascophyllum nodosum) or sea lettuce (Ulva rigida) macroalgae in a 12-week trial. RESULTS: The results demonstrated there was no significant difference in fish condition, gut morphology or hindgut microbiota between the U. rigida supplemented fish group and the control group at any time-point. This trend was not observed with the A. nodosum treatment. Fish within this group were further categorised as either 'Normal' or 'Lower Growth'. 'Lower Growth' individuals found the diet unpalatable resulting in reduced weight and condition factor combined with an altered gut morphology and microbiome relative to the other treatments. Excluding this group, our results show that the hindgut microbiota was largely driven by temporal pressures with the microbial communities becoming more similar over time irrespective of dietary treatment. The core microbiome at the final time-point consisted of the orders Vibrionales (Vibrio and Photobacterium), Bacteroidales (Bacteroidetes and Macellibacteroides) and Clostridiales (Lachnoclostridium). CONCLUSIONS: Our study indicates that U. rigida macroalgae can be supplemented at 10% inclusion levels in the diet of juvenile farmed Atlantic cod without any impact on fish condition or hindgut microbial community structure. We also conclude that 10% dietary inclusion of A. nodosum is not a suitable feed supplement in a farmed cod diet.
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Authors: C Keating; M Bolton-Warberg; J Hinchcliffe; R Davies; S Whelan; A H L Wan; R D Fitzgerald; S J Davies; C J Smith; U Z Ijaz Journal: NPJ Biofilms Microbiomes Date: 2022-05-04 Impact factor: 8.462