Effects of dietary mannan oligosaccharides on growth, body composition, and intestine and liver histology of rainbow trout, Oncorhynchus mykiss

This study investigated the effects of dietary mannan oligosaccharides (MOS) on growth, body composition, and small intestine and liver histology of rainbow trout (Oncorhynchus mykiss Walbaum). Experimental diets were supplemented with 0 (control), 1.5, 3.0, or 4.5 g MOS per kg commercial trout feed and randomly assigned to treatment groups. Enhanced growth performance was generally observed in fish fed the diet supplemented with 1.5‰ MOS. Villi of fish fed diets supplemented with 1.5 or 3.0‰ MOS were longer than those of fish fed 4.5‰ or no dietary MOS (p<0.05). Protein contents increased as the rate of MOS increased (p<0.05). There were no significant differences in feed conversion ratio, protein efficiency ratio, or hepatosomatic index (p>0.05) and MOS had no detrimental effects on the intestine. * Corresponding author. Tel.: +90-326-2455845 ext. 1302, fax: +90-326-2455817, e-mail: agenc@mku.edu.tr