Assessment of sesame meal as a soybean meal replacement in European sea bass (Dicentrarchus labrax) diets based on aspects of growth, amino acid profiles, haematology, intestinal and hepatic integrity and macroelement contents.

An 87-day feeding trial was carried out to assess the use of dehulled and defatted sesame seed meal (SM) as a partial dietary replacement for soybean meal (SBM) at 0%, 15%, 30% and 45% (SM0, SM1, SM2 and SM3, respectively) in juvenile sea bass stocked in 12 tanks (0.5 m3) and with an initial weight of 24 ± 0.50 g. All diets were isonitrogenous (~ 47% crude protein), isoenergetic (~ 22 MJ/kg) and tested in triplicate. The lowest growth and feed utilization efficacy were detected in fish fed the SM3 diet; moreover, diets with a lower SM content did not have significant effects relative to the CTR diet. Fish biochemical analysis indicated a gradual decrease in carcass protein content coinciding with an increase in lipid deposition and viscerosomatic index values as the SM level in the diet increased. The macroelements' (P, Na and K) fish contents did not differ significantly among groups. The SM3 group had the lowest Ca and highest Mg contents among the experimental groups. The fish amino acid profile indicated slight alterations in essential amino acid percentages among groups. Haematological analysis and serum biochemistry indicated that using SM at a content of up to 30% had limited negative impacts on fish health. Liver histological inspection indicated that higher levels of SM led to severe hepatocyte infiltration with slight signs of necrosis in fish fed SM3 diet. Intestinal histological examinations indicated that the distal portion of the intestine was the portion most affected by SBM replacement with SM with signs of intestinal inflammation in SM3 group.