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FEATURE

GUT HEALTH

IN 4 (EASY) STEPS

M

uch has been made of gut health recently. By unpacking the concept, we can arrive at a better understanding of the driving factors, influences, indicators and implications of gut health for aquaculture.

1 - Gut health is crucial for aquaculture

One of the first challenges that we face in aquaculture is precisely the environment where fish live, breathe, eat and defecate: the water. In aquaculture, fish and shrimp live in close connection with the surrounding environment. Through the ingestion of water, aquatic farmed animals constantly face pathogens and environmental stress in the gut. If we would compare, for example, the amount of bacteria in air and water, you will be faced with about 1,000,000 bacteria per millilitre of water in coastal areas. In aquaculture systems or special in intensive systems, this number will be considerably higher. Adding to this, most bacteria found in aquatic environments are opportunistic, and therefore have the potential to become pathogenic. Good gut health is important in limiting the risk.

2 - Defining gut health

The term ‘gut health’ is part of a complex animal health definition that relies on a diverse set of gut performance indicators (depicted in lower portion of Figure 1). In aquaculture, the diversity of farmed species makes this even more complex. We would say that the key feature of the gastrointestinal tract comprises its ability to digest feed and make it suitable for absorption and growth under healthy conditions, e.g. in the absence of disease, leading to improved animal performance. At BIOMIN we define gut performance management according to three objectives (Table 1).

3 - Understanding gut health as a whole

Understanding gut health requires the elucidation of the complex interactions between different components that will allow the gut to perform under normal physiological functions and to maintain homeostasis, thereby supporting its ability to withstand infections and non-infectious stressors. Such complex interactions can be grouped in three pillars: animal physiology, nutrition and environment (shown as main categories in Figure 1). These three main factors interact, influencing the gastrointestinal microbiota community, and consequently, gut performance.

Fish physiology

An animal´s physiological status can be characterised by its metabolism, which is set according to; gastrointestinal anatomy/ physiology variations according to each species, feeding habits, diet, nutrition and physiological condition. It is further influenced by health challenges and defense mechanisms. Defence mechanisms will have particularities inherent to each species and some pathogens will also be species-specific.

by Rui Gonçalves, Scientist, Gonçalo Santos, R&D Manager at BIOMIN

Nutrition

The second pillar focuses on nutritional aspects, where raw material quality and origin sources in particular can affect

20 | January | February 2016 - International Aquafeed

Jan | Feb 16 - International Aquafeed magazine