Dietary taurine improves the growth performance, health status and liver histopathology of meagre (Argyrosomus regius) fed a reduced fish meal diet

Research has focused on alternative plant materials or additives that can be used instead of fish meal due to limited stocks and increased feed prices, although it is important for carnivorous fish species. Taurine is a functional amino acid supplemented to low fish meal diets to improve the growth performance of fish. In this study, eight experimental diets with 0%, 0.5%, 1% and 2% ratios of taurine supplemented (T0, T0.5, T1 and T2) high (HFM) and low fish meal (LFM) diets were prepared (defined as HFMT0, HFMT0.5, HFMT1, HFMT2, LFMT0, LFMT0.5, LFMT1 and LFMT2). The experiment was carried out in twenty-four 400 L rectangular fiberglass tanks conducted in a marine water system, and fish (initial mean weight of 23.5 g) were stocked in each tank. The nutrition trial was carried out for 90 days with three replicates. Meagre fed with the HFMT1 diet had a higher final mean weight (FMW) and specific growth rate (SGR) than fish fed with HFMT0 and all LFM diets. Including taurine in all LFM diets also enhanced growth performance. The FMW and SGR of fish fed the LFMT0.5 diet were similar when compared to HFMT0 (P>0.05) and increased than that of other LFM diets with taurine (P<0.05). Meagre fed the LFM0.5 diet had a lower feed conversion rate (FCR) than those provided for all HFM diets, although there was no significant difference between treatments. Dietary taurine has decreased the hepatosomatic index (HSI), viscerosomatic index (VSI) and total ammonia-nitrogen excretion (TAN), irrespective of taurine and fish meal levels. Including dietary taurine at both fish meal levels enhances the number of red blood cells (RBC) and whole-body amino acids of meagre. The most remarkable conclusion of this study is the inclusion of taurine in low fish meal diets improved growth performance and profitability in meagre, and the level of 0.5% has been recommended.