Researchers from Arish University, Aswan University, ARC Dokki Gaza, Suez Canal University, Zagazig University, University of Santo Tomas, University of the Philippines Manila, and Far Eastern University studied the potential effects of dietary supplementation with β-1,3 glucan and fructooligosaccharides (β-1,3 GF) on antioxidant activities, immune response, growth of Pacific white shrimp (Litopenaeus vannamei) and resistance to Fusarium solani infection.
They studied four different levels of β-1,3 GF (0, 0.5, 1.0, and 1.5 g kg-1) given to juvenile shrimp for 75 days.
Black spot disease (BSD)
The black spot disease (BSD) caused by Fusarium spp., is considered one of the main problems in shrimp-producing countries.
The fungus Fusarium spp. causes various diseases in plants and animals, resulting in decreased yields, lethal mycotoxins, and disease outbreaks.
Litopenaeus vannamei are highly susceptible to black spot disease, and when diseased they exhibit symptoms such as black gills and serious tissue damage, with high mortality.
Fusarium solani has been identified as the main causative organism of shrimp black spot disease.
β-1,3 GF improves shrimp performance
The results of the study highlight that feeding shrimp 1.0 and 1.5 g kg−1 of β-1,3 GF considerably increased the activity of digestive enzymes in shrimp.
“The results revealed that long-term supplementation with 1.5 g kg−1 β-1.3 GF significantly improved shrimp weight gain, feed conversion ratio, and digestive enzyme profiles, compared to control diet group,” they report.
However, the researchers point out, there were no substantial variations in the moisture, crude protein, total lipid, and ash contents in the muscles of shrimp fed different diets.
Antioxidant activities
The results of the study reflect the main role of β-1,3GF as a potential antioxidant due to its high content of phenolic compounds, which is probably responsible for its potent antioxidant activity.
“Surprisingly, all activities of antioxidants (superoxide dismutase, catalase, glutathione peroxidase) and immune biomarkers (lysozyme, total hemocyte count, phenol oxidase, and respiratory burst) were significantly increased with increasing levels of dietary β-1,3GF. of shrimp, and the highest values were recorded in the 1.5 g kg−1 diet groups”, they highlighted.
Challenge tests
“Regarding the hematological profiles in this study. The values of total hemocytes increased proportionally according to the increase in the level of β-1,3 GF; the highest values were registered in the group fed with the highest dose (1.5 g Kg-1)”, they report.
Furthermore, the challenge test results revealed that Fusarium solani could cause a high mortality rate (86.7%) in a group of shrimp fed a normal basal diet within the first 14 days.
“All groups of shrimp treated with diets with different doses of β-1.3 GF showed high resistance against Fusarium solani, represented by lower cumulative mortality rates (20-43.3%) compared to the control group,” they report. .
The survival rate was clearly higher in the group of shrimp fed the diet containing 1.5 g kg-1 of β-1,3 GF.
“Based on our findings, β-1,3 GF therapy may be a suitable alternative to control fungal infections in shrimp farming systems,” the researchers note.
Conclusion
“Overall, this study recommends an adequate level of β-1,3GF incorporation that could improve growth performance and improve antioxidant activities, non-specific immunity, and disease resistance of L. vannamei, with an optimal level of 1.5 g kg−1”, they concluded.
Reference (free access)
Eissa, El-Sayed Hemdan, Ragaa A. Ahmed, Nadia A. Abd Elghany, Amal Elfeky, Saadea Saadony, Norhan H. Ahmed, Salah El-Sayed Sakr, Geraldine B. Dayrit, Charlene Princess S. Tolenada, Adlene Anne C. Atienza, Mahmoud Mabrok, and Hala F. Ayoub. 2023. “Potential Symbiotic Effects of β-1,3 Glucan, and Fructooligosaccharides on the Growth Performance, Immune Response, Redox Status, and Resistance of Pacific White Shrimp, Litopenaeus vannamei to Fusarium solani Infection” Fishes 8, no. 2:105. https://doi.org/10.3390/fishes8020105
