Animal welfare in modern production systems for fish

Last changed: 25 February 2019

Study 3 – Effect of alternative feed resources on the fish normal intestinal micro flora and the intestinal barrier function.

Feed composition is one of the most important factors that can affect fish health and welfare throughout their life. The level of nutrient palatability and absorption are central questions, but more specifically the effect of different feed components on intestinal barriers, immune system and normal intestinal flora of fish.

We know quite well that the food we and the animals consume can be both healthy and harmful. Animals cannot choose what to eat, but must be satisfied with what is offered. The introduction of new ingredients in fish diets can affect absorption, immune status, and the intestinal barrier function of fish in both positively and negatively aspects. Various dietary substances can react directly with the lining of the gastrointestinal tract or affect the composition of the normal intestinal microbial flora. We will carry out tests on rainbow trouts to identify if the intestinal barrier and immune system are affected by these new diets. We will also take samples of intestinal contents from different parts of the gastrointestinal tract and by using the "Next-Generation Sequencing" technique mapping the gut micro flora and investigate if the commensal micro-flora is affected when animals are fed with feed based on microbial biomass.

We will also monitor how nutrients are broken down and absorbed in the intestine of fish fed with different protein feeds. Fish provided with a blood catheter in the dorsal aorta will be used for repetitive blood sampling to achieve a clearer picture of how different feed ingredients are broken down and absorbed in the gastrointestinal tract. This will also allow use to evaluate blood parameters without handling and stressing the fish.

FRESH - study 3

Figure 1. Schematic description of catheterization of rainbow trout for blood sampling via dorsal aorta in free-living fish.

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