Summary
The present study was conducted to evaluate the effects of Grobiotic®-A, a commercial
prebiotics, when administered in feed on the growth performance, plasma thyroid
hormones and mucosal immunity of great sturgeon (Huso huso). The commercial prebiotic
mixture was supplemented in the diets at four different levels (i.e. 0.0% as control,
0.5%, 1% and 2%, in three replicates, 20 fish per replicate) and fed to the fish for an
8-week period wherein 240 fish were cultured in 1,800-L fiberglass tanks that formed
part of a flow-through system. Water temperature was maintained at 20.4 ± 1.5°C.
Significant changes in growth performance parameters were observed, but only in
those groups fed with 1% and 2% prebiotics. Specifically, marked improvements relative
to the control group were observed in percentage weight gain, body weight gain,
feed conversion ratio and specific growth rate in prebiotic-fed fish. The levels of
plasma thyroid hormones, specifically thyroxine and thyroid stimulating hormones
were significantly elevated in the group receiving 2% prebiotics. Activities of lysozyme
and alkaline phosphatase in skin mucus were significantly enhanced in prebiotics-fed
groups, particularly at an inclusion level of 1% and higher (2% group compared to the
control). Inhibitory activity of the skin mucus against pathogens, particularly Streptococcus
iniae and Yersinia ruckeri, was significantly improved following prebiotic feeding.
Taken together, dietary inclusion of GroBiotic®-A promoted growth, modulated
thyroid hormones, and enhanced mucosal immunity of H. huso. This prebiotic mixture
has the potential for use in improving the growth performance and health status of
farmed great sturgeon.