14 DAY TRIAL // Salmon grown in fisheries is often fed legumes in order to grow faster. The same is done for livestock on land, so that higher egg and milk productions can be achieved. However, a new study shows that vegetables contain so-called anti-nutritional substances, which can reduce fishery performances.
The new research was conducted by doctoral student Elvis Chikwati, and was defended on December 3, at the Norwegian School of Veterinary Science (NVH). The work was entitled Diet-induced physiological and pathophysiological responses in the intestine of Atlantic salmon (Salmo salar L.) - effects of plant protein ingredients and anti-nutritional factors.
While it is true that the seeds of soya, peas, lupins and other legumes are very rich in proteins, these feedstuffs also contain high amounts of substances that are alien to fish and their environments. They are currently used around the world, due their widespread availability and low costs.
Chikwati's work suggests that legume seeds can have a pronounced negative effect on the growth and health of salmon, both in fisheries and in the wild. Understanding the effects of feed on fish populations may be essential for maintaining a steady supply as stocks dwindle around the world.
“The maturation of intestinal cells was delayed in fish that were given soya in their feed. The cells never reached full maturity. They also found their way more rapidly to the top and appeared to divide, not just down in the folds of the intestines, but also along the whole length of the intestinal fold,” the NVH reveals in a statement.
Changing regular feed to soya in a test salmon population led to changes in the fishes' intestine functions within just two days. After five days, the effects were much more pronounced, and led to enteritis, which is an inflammation of the intestines.
The anti-nutritional substance “saponin from soya, when given together with peas, resulted in the same inflammatory reaction as when soya was given alone. This means that the saponin is the cause of the inflammation, either on its own or in combination with other components found in legumes,” experts from the university explain.
Using the new data, it may become possible to develop new feeding patterns for fisheries around the world, so that their productivity is increased, while salmon and other fish remain healthy and fit for human consumption.