Feeding turbot based on ingredients from the Baltic Sea region: Comparative study with conventional feed ingredients

The European aquaculture industry still depends on imported raw materials like fish meal and soy bean meal from overseas for fish feeds. To evaluate the potential of regional feed ingredients for nutrition of the carnivorous turbot (Psetta maxima) a long-term study was conducted to compare conventional and regionally sourced feed ingredients with regards to growth performance, health and filet quality of fish.

One conventional diet (FM30) containing 30% fish meal and 20% soy bean meal and two diets, in which both ingredients were partly (FM15) or totally (FM0) substituted by regionally originated mussel meal, rapeseed protein concentrate and yeast were produced. In total 1476 juvenile turbot (21.6 g) were allocated in triplicates in a recirculating aquaculture system and fed daily for 292 days until apparent satiation.

Results showed that comparable growth rates could be achieved in fish fed completely regionally sourced diets (FM0) in comparison with conventional fish and soy based diets (FM30). However, best growth performance was observed in fish fed a mix of all test ingredients (FM15), where a similar feed conversion ratio (FCR) but an increased daily feed intake (DFI) in comparison with FM30 was observed. The FCR decreased in group FM0 and the DFI increased in both diets FM0 and FM15 in comparison with FM30. Furthermore hepatosomatic index (HSI) was highest and protein efficiency ratio (PER) lowest in treatment FM0. No significant differences were observed in-between dietary treatments with regards to other investigated physiological parameters and health status of fish such as splenic index, haematocrit and mortality. Furthermore in the sensory panel no significant differences in filet quality were observed between group FM30, FM15 and FM0.

It was concluded that turbot can be grown entirely based on regional ingredients without adverse effects on growth performance, health and product quality of fish. However, in future slightly reduced performance of fish fed regionally originated feed source could be overcome by optimized processings and thereby improved nutritive characteristics. 

Report: Feeding turbot based on ingredients from the Baltic Sea region: Comparative study with conventional feed ingredients