EFFECTS OF TAURINE SUPPLEMENTATION IN DIET WITH PARTIAL REPLACEMENT OF FISHMEAL BY SOYBEAN MEAL ON JUVENILE OLIVE FLOUNDER Paralichthys olivaceus

Higher prices and scarcity of fishmeal  creates new paths to formulate feeds to replace fishmeal with cheap plant proteins.  A study was conducted to investigate the effect of taurine supplementation in order to compensate negative effects  replacement  of fishmeal (FM) with Soybean meal (SBM). A FM based diet was considered as the control and six other diets were formulated to replace FM at 20, 30 and 40% without taurine supplementation (SM20, SM30 and SM40) and with taurine supplementation at a level of 1% (SM20-T, SM30-T and SM40-T) respectively.

Three replicated groups of juvenile olive flounders were fed one of the experimental diets for 10 weeks and their growth performance, feed utilization, innate immunity, intestinal morphology and liver IGF-1 gene expression levels were examined.

The  SM20-T group showed higher growth and feed utilization compared with all other groups. However, with the increasing levels of FM replacement, taurine did no t completely compensate for the growth reduction compared with the control.

Total Immunoglobulin (TIg) levels and lysozyme activity of plasma and serum increased with the supplementation, which could be an evidence of the health of the fish.

Plasma Alanine transaminase (ALT) and Aspartate transaminase (AST) levels were decreased compared with the control group in taurine supplemented groups compared to un-supplemented groups.  Therefore, taurine might have completed compensated the liver damage.

There were clear IGF-1 relative expression s in supplemented groups, however, only SM20-T had a higher level than the control.       

These results reveal that  neither  growth  nor health of the fish were  altered with FM replacement by  20% SBM with taurine supplementation . However, when the level of replacement increased, taurine couldn't compensate completely for the observed adverse health effects.