The effect of feed withdrawal on metabolism, swimming capacity and haematology in Atlantic salmon.
The purpose of these experiments will be to study the fundamental physiology of Atlantic salmon in response to periods of food withdrawal. Specifically, we want to establish how baseline metabolic requirements may change during up to four weeks of feed withdrawal, which will allow us to define the time frames for when Atlantic salmon shifts strategy between a digestive/growing metabolic state to a lower metabolic mode of energy saving. In addition, we want to study how the swimming performance is affected. Swimming performance represents the aerobic capacity and the overall robustness of the fish to cope with challenges in its environment, but it is presently unclear how intermediate periods without food affect these traits. In conjunction with the swim trials, we will assess the haematological effects during control conditions, when exhausted from swimming and following brief periods of recovery. This will reveal the overall level of stress associated with different periods of feed withdrawal, as well as whether the ability of the fish to cope with and recover from acute exercise stress is affected.
The fish used in the proposed experiments will experience normal undisturbed routine husbandry conditions for the majority of the time. For the estimation of metabolic rates, intermittent-flow respirometry will be used where fish will experience some handling stress associated with movement into the experimental setup. For assessment of swimming performance, fish will be tested in a large swim tunnel. Here they will be swimming until they are exhausted which causes respiratory, endocrine and osmotic disturbances as the full aerobic capacity of the fish becomes mobilized. For blood sampling, fish will be anaesthetized beforehand. Immediately following all measurements, the fish will be euthanized.
The expected scientific knowledge gained in these proposed experiments includes several key aspects of the fundamental physiology of Atlantic salmon in relation to feed withdrawal such as baseline metabolic responses, swimming abilities, coping strategies and the capacity to handle acute stress.
These fundamental insights in Atlantic salmon biology will also have significant societal value, as the results will have implications for some aquaculture practises regarding animal welfare and production performance. For instance, the salmon industry is currently seeking to expand production to off-shore locations, where persisting rough weather conditions occasionally will make it impossible to feed the fish for extended periods. At the same time the fish will have to use their swimming abilities to cope with strong current conditions. The proposed experiments here will allow for establishment of much needed science-based welfare guidelines for such farm conditions.
In total we wish to use 190 Atlantic salmon in the planned experiments. Animal models are required here as we are investigating whole-organism performance traits. These parameters are too complex to investigate in a meaningful way with other methods. We have followed the 3R’s by minimizing number of replicates per treatment group without compromising expected statistical power, and by carefully planning experimental protocols according to established and refined standards within the field.
The fish used in the proposed experiments will experience normal undisturbed routine husbandry conditions for the majority of the time. For the estimation of metabolic rates, intermittent-flow respirometry will be used where fish will experience some handling stress associated with movement into the experimental setup. For assessment of swimming performance, fish will be tested in a large swim tunnel. Here they will be swimming until they are exhausted which causes respiratory, endocrine and osmotic disturbances as the full aerobic capacity of the fish becomes mobilized. For blood sampling, fish will be anaesthetized beforehand. Immediately following all measurements, the fish will be euthanized.
The expected scientific knowledge gained in these proposed experiments includes several key aspects of the fundamental physiology of Atlantic salmon in relation to feed withdrawal such as baseline metabolic responses, swimming abilities, coping strategies and the capacity to handle acute stress.
These fundamental insights in Atlantic salmon biology will also have significant societal value, as the results will have implications for some aquaculture practises regarding animal welfare and production performance. For instance, the salmon industry is currently seeking to expand production to off-shore locations, where persisting rough weather conditions occasionally will make it impossible to feed the fish for extended periods. At the same time the fish will have to use their swimming abilities to cope with strong current conditions. The proposed experiments here will allow for establishment of much needed science-based welfare guidelines for such farm conditions.
In total we wish to use 190 Atlantic salmon in the planned experiments. Animal models are required here as we are investigating whole-organism performance traits. These parameters are too complex to investigate in a meaningful way with other methods. We have followed the 3R’s by minimizing number of replicates per treatment group without compromising expected statistical power, and by carefully planning experimental protocols according to established and refined standards within the field.