In this experiment, the beneficial effects of
mannan-
oligosaccharide (MOS) on
immunology and intestinal
microbiology of
Nile tilapia juveniles was demonstrated. Prior to this, three levels of MOS in
Nile tilapia diets (1, 8, and 15 g.kg−1) were tested, and hematological
parameters,
serum lysozyme, and intestinal
microbiology were analyzed. The fish
blood was sampled at day zero (basal sample) and after 45 days of trial, and the
intestinal microbiota was evaluated at the end of the experiment. After 45 days of trial, fish fed 8 and 15 g.kg−1 of MOS presented an increase in both aerobic and
lactic acid bacteria numbers in their guts. The MOS
feeding also increased the counts of total
leukocytes,
monocytes, and
lymphocytes of fish, but a decrease in
neutrophils was also observed. Additionally, the
serum lysozyme was higher in all fish fed MOS. The dietary MOS is able to modulate the
intestinal microbiota, increasing the number of beneficial
bacteria, and immunostimulates the
Nile tilapia juvenile, giving rise to
white blood cells and
serum lysozyme.(AU)