A clear connection has been found between an excess of minerals in the feed and development of black blood vessels in farmed cod
"Black blood vessels in fillets from farmed cod represent a potential future financial loss. Signals from the industry indicate that this can be used as a quality criterion and can lead to a lower sales price", says Director of Research Even Stenberg.
The connection between black blood vessels in farmed cod and copper in the mineral blend (mix) added to the feed has now been studied.
"The results show that copper in quantities exceeding the cod's natural needs increase the incidence of black blood vessels", says Scientist Marie Cooper.
Cod that ate feed without (added) copper or other mineral additives had no negative adverse effects. Growth and mortality rates were not different in groups fed unsupplemented feeds when compared to those fed mineral supplements. The results also show that farmed cod given feed without a mineral blend had a lighter skin color.
Fiskeriforskning has conducted systematic studies for several years to document and follow the quality development of farmed cod. For the aquaculture industry, it is important that focus is set on mineral supplements for saltwater fish in aquaculture related to muscle quality.
The study is financed by Innovation Norway. The testing will continue in 2006, and will include studying whether fish that have developed black blood vessels can have the extent of these reduced by changing the feed and feeding regime.