Mortality and developmental deformities during the larval stage are bottlenecks in cod farming. In the wild the cod larvae feed on copepods and in intensive farming they need to feed on rotifers due to their immature digestive system. Rotifers contain less iodine, selenium, manganese, copper and zinc than copepod and research at the National Institute of Nutrition and Seafood Research (NIFES) show that cod larvae fed rotifers enriched with iodine and selenium have a higher survival rate than control larvae.
“This indicates that the control rotifers were deficient in either iodine or selenium or both. In a new project we will examine whether adding selenium-enriched yeast to rotifers will supply the cod with enough selenium and thereby increase growth and survival rates and decrease the number of deformities,” says researcher Kristin Hamre in the Aquaculture Nutrition Research Programme at NIFES. The project is in collaboration with Alltech AS, who produces the selenium-rich yeast Sel-Plex.
“Selenium is a component of an enzyme that prevents cod from absorbing rancid fatty acids. This may affect growth, survival and the development of deformities. We know, for example, that rancid feed results in deformities,” says Hamre.
