Bone development and nutrition
Bone is largely made of specialised proteins and the minerals phosphorus and calcium. Other minerals, such as manganese, zinc and magnesium help to strengthen bone formation as they are important cofactors for the enzymes that are involved in skeletal development. For bones to grow into their final shape, a good balance is needed between degradation and formation. Several vitamins help to regulate this balance (vitamins A, C, D and K) and are therefore important, together with minerals, for the correct development of the skeleton.
Malnutrition can result in bone deformities
Incorrect mineral or vitamin levels in the feed can result in abnormal development and weak skeletons in the fish. For example, a lack of the essential mineral phosphorus can result in deformities of the head, ribs, fins and spine in fish. Similar deformities also occur if the feed contains too much vitamin A. We also know that a lack of vitamin C leads to spinal deformities in fish.
To ensure good bone development in farmed fish, the feed must contain sufficient amounts of these nutrients. It is also important that they do not get too much, as this can be toxic and damage the skeleton and organs. Another challenge is that when the feed contains high levels of some of the minerals, the fish will start to excrete more of them. When farmed fish excrete extra phosphorus, for example, it can result in increased environmental impact.
- Environmental impact
Early stages of bone development
Marine species, such as halibut, cod and wrasse are fed live feed at the larval stage. Some of the nutrients that we know are important for bone formation must first be fed to the live feed organisms (rotifiers and Artemia) in order for these organisms to contain enough of these nutrients when they are fed to the marine fish larvae.
- Live feed
In the early phase of life, the development of fish is very susceptible to influence. This is also the case for the development of the skeleton. Incorrect amounts of important nutrients for bone development (see above) and essential fatty acids (omega-3 and omega-6) in the larval feed will result in deformities that will materialise at a later stage of development, for example in the fry phase. NIFES conducts research on how the composition of nutrients in the live feed organisms can be balanced to avoid deformities arising at a later stage in the development of the fish. Too high levels of vitamin A in live feed can lead to changes to the jaws and coalesced vertebrae. NIFES also conducts research on what other nutrient deficiencies or excess in live feed that can contribute to the development of deformities in fish larvae.