Access to marine raw materials for fish feed production is limited. Any future increase in the numbers of farmed salmon will therefore necessitate an increased use of feeds of plant origin, therefore it is important to obtain knowledge of just how plant-based feed affects the health of fish.
Simultaneously, the latest research has contributed to a basic understanding of how fish digestive and immune systems function, writes Nachste Meldug in an InnovationsReport.
According to the report, Lilleeng utilised soya for his plant ingredient and used molecular-biological methods to study what happens in the fish intestine. The research comprised a series of feeding trials with salmon, of both short and long durations, so that both acute and more chronic reactions in the intestine could be studied.
Any increase in the Norwegian production of salmon will necessitate an increased use of plant-based feeds. Replacing marine ingredients with plant-based ingredients exposes fish to a series of "foreign" components, for example, starch and anti-nutrients that may upset natural processes occurring in the intestine, says Mr Meldug. Plant components such as lectins, saponins, phyto-oestrogens, phytic acid, tannins and others, which do not exist in the natural feed of wild fish, may disturb digestive processes and affect health. Plant ingredients also introduce proteins that may stress the immune system of the intestine.
Lilleeng used soya meal as the source of his ingredients, which is known to contain a series of anti-nutrients and to disturb the intestinal function of salmon. Lilleeng showed that intestinal immune defences become activated immediately feeding with soya commences. He also showed that enzymes normally associated with protein digestion have abnormally high levels of activity in the intestines of salmon with enteritis as a result of soya feeding. It appears that the intestinal mucous membrane, which previously has not been considered to be a source of these enzymes, also contributes to the high levels.
Plant Feedstuffs: Inside the Salmon Gut
GLOBE - A researcher has increased our understanding of how plant-rich feedstuffs, which contain a series of anti-nutrients, affect the digestive processes and immune system of the salmon intestine.
