Molecular effects of mannanase-hydrolyzed coprameal to intestinal immunity in the Pacific white shrimp (Litopenaeus vannamei )
To mitigate disease outbreak, an alternative approach through enhancing shrimp immunity was explored. Mannan oligosaccharides (MOS) have been previously reported to enhance shrimp immune system. Here, coprameal samples were digested with mannanase to yield MOS, namely, mannanase-hydrolyzed coprameal (MCM) and feasibility of MCM as shrimp immunostimulant in grow-out ponds was determined. Pacific white shrimp (Litopenaeus vannamei) were fed with the commercial diet containing 1% MCM as the MCM-supplemented group and compared to the non-MCM control diet. There was no significant difference in survival rates between the MCM-supplemented and the control groups throughout the 4-month-period of the trial (p > 0.05). Gene expression analysis in shrimp intestines revealed that the transcript levels of antimicrobial peptides (anti-lipopolysaccharide factor isoform 1 (alf1), penaeidin (pen3a) and crustin (crus)) and lysozymes (lyz) were not significantly different in the MCM-supplemented group. Meanwhile, C-type lectin and toll-like receptor transcript levels, whose gene products play roles as pattern recognition proteins, were significantly higher in a group fed with MCM for 2- and 4-month periods than those of the control group (p < 0.05). The increased transcript levels of C-type lectin and toll-like receptor provide evidence for potential implementation of MCM as feed supplement to modulate shrimp immune system.