The right nutrition means more robust fish
The right nutrition makes fish more resistant to infection, while fish that suffer from malnutrition are often weak, thereby contracting diseases more easily. NIFES contributes to increasing our knowledge about what individual nutrients and nutrient cocktails fish need to ensure production of robust fish which is resistant to infection pressure, inflammation and stress.
The balance between omega-6 and omega-3 is important for fish health and their resistance to disease, but research has not yet determined the optimal balance to ensure the production of robust fish.
NIFES has broad knowledge about the many nutrients that farmed fish need to ensure good fish health and the production of robust fish. For example, antioxidants are important to fish’s ability to regenerate damaged tissue after injury, and the amino acids histidine, taurine and arginine play key roles in fish metabolism and in ensuring a robust fish.
Ability to handle stress
Stress can weaken the immune system of fish. Farmed fish can be exposed to stress among other things in the form of changes in temperature, crowding during handling and incorrect nutrition. Stressed fish react by increasing the concentration of the hormones adrenaline and cortisol and sugar in their blood. The body is mobilised for flight, which leads to an imbalance that makes the fish less resistant to infection pressure and more susceptible to disease during this period.
Fish handle stress better if they are given optimal feed that covers all their nutrition needs. Nutrients that have been linked to fish’s ability to handle stress are vitamin C, vitamin E and polyunsaturated fatty acids such as omega-3 and omega-6.
New ingredients in the feed, especially plant ingredients that are not sufficiently refined to remove anti-nutrients, can result in damage to the fish’s intestines. Intestinal health is important because the intestines are the body’s first defence against infective agents. Damage to the intestine leads to poorer digestion and utilisation of the feed. In turn, this leads to poorer growth and makes the fish more susceptible to infection.
Plant ingredients that are not refined contain anti-nutrients that are damaging to the intestinal mucous membranes. Anti-nutrients prevent nutrients from being absorbed and utilised by the body. Damage to the intestines is more severe the coarser and more unrefined the plant ingredients used are. Soy meal in particular can lead to inflammation of the intestines in fish.