Background:
Mannanoligosaccharides (MOS) usage in fish production has drawn more attention because of its positive benefits on disease resistance and fish performance.
Aim:
The ongoing research was executed to assess the potential advantages of Bio-Mos® dietary supplementation regarding the growth outcomes, physiological response, oxidative biomarkers and immunity linked gene expression in Nile tilapia (Oreochromis niloticus) fingerlings exposed to bacterial infection with Aeromonas hydrophila.
Methods:
Four experimental diets were developed using 30% protein baseline diet, with Bio-Mos® added at variable levels; 0.0, 0.5, 1 and 2 g/kg, respectively. 240 healthy Nile tilapia fingerlings were split into four groups at random and assigned into 12 glass aquarium (three replicates of 20 fish/ treatment). Diets were admitted at 3% rate of fish biomass/aquarium for 8 weeks. Following the feeding trial, fish from every treatment were intraperitoneally injected with pathogenic Aeromonas hydrophila, and then observed for 15 days to record the survival rate post challenge.
Results:
Results revealed significant improvement in growth performance, physiological response, immunological parameters (Phagocytic index, Phagocytic activity, lysozyme) and antioxidant parameters (catalase, malondialdehyde, glutathione peroxidase and superoxide dismutase) among Bio-Mos® treated groups. Moreover, Bio-Mos® increased the expression of TNF-α and IL-1β, genes linked to the liver immune system. growth related genes (GHr), antioxidant related genes (SOD and GSH-Px). In fish subjected to pathogens, dietary MOS supplementation could significantly lower oxidative stress, showing promise as a preventative supplement for Nile tilapia in place of antibiotics. On the other hand, Bio-Mos®considerably improved each of the three intestinal morphological measures (villus width, villus length and crypt depth), showing the best overall intestinal structure-improving impact. The challenge with A. hydrophila caused marked degenerative alterations in the intestine, hepatopancreas, spleen and posterior kidney of Nile tilapia, in the control group. However, lesion severity was greatly decreased and showed marked amelioration with increased concentration of Bio-Mos®. The A. hydrophila challenged groups revealed 100% survival rate mainly among the Bio-Mos®supplemented groups.
Conclusion:
It is recommended to enrich the Nile tilapia fingerlings diets with 2 g.kg−1 of MOS for better results on growth rate, physiological response, immunological response and intestinal absorptive capacity.
Key words: Aeromonas hydrophila, Immunity linked gene expression, Mannanoligosaccharide, Nile tilapia, oxidative status
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