Correspondingly to our results on growth, genes involved in
growth and development were not influenced by the b-glucan
treatment. This is the first time b-glucan effects on growth hormone
gene expression were studied in fish but it is in accordance to
studies in pigs, where b-glucan also had no effect on growth hormone
production [55,56] Nevertheless, our data suggest that bone
mineralization (i.e. osteocalcin gene expression) might be
increased in turbot larvae fed with MacroGard® during the later
time period (24 dph). To the authors knowledge no data is yet
available on the effects of b-glucan on skeletal development in fish
larvae. As b-glucan does not have any nutritional value, it is possible
that the enhanced osteocalcin expression is a secondary effect due
to the altered gut microflora in the MacroGard® fed fish. In sea bass
(Dicentrarchus labrax) for example it was shown that bone development
was enhanced in response to probiotic lactic acid bacteria. In future research it should therefore be investigated if bglucan
can enhance bone structure and prevent malformations.