Mannoprotein dietary supplementation for Pacific white shrimp raised in biofloc systems

In order to reduce disease outbreaks in shrimp aquaculture, biosafe farming practices have been created, such as the biofloc system and the use of feed additives to improve shrimp immune response and growth performance. Many studies with feed additives have tested probiotics in biofloc rearing systems; yet to date, no studies have reported on the use of prebiotics in the feed of farmed shrimp in biofloc systems. Moreover, the effects of mannoprotein (MP) prebiotics on shrimp and shrimp farming are also unknown. Therefore, this study aimed to evaluate the effects of dietary supplementation with mannoproteins (MP) on the performance, immune response, and midgut intestinal villi of L. vannamei raised in a biofloc system. Three diets with different MP concentrations were formulated (0.02%; 0.08%; 0.12%) and one control group without MP additive. The experiment utilized 12 experimental units (800 L) stocked with 400 shrimp/m3, with 3.64 ± 0.07 g of initial weight, in triplicate. Shrimp were fed four times per day, and both histology of the midgut and growth indices were assessed after 65 days. Intestinal villi presented a larger internal surface area in animals that were fed dietary supplements of 0.08% and 0.12% MP (p < .05). Shrimp fed with MP showed an approximate 10% increase in survival compared to animals in the control treatment (p < .05). No statistical differences were found in the growth parameters (final weight, weekly weight gain, final biomass, feed efficiency) or survival after challenge with Vibrio parahaemolyticus. Prior to infection, no differences were found in any of the immunological parameters analyzed. However, after infection, the production of superoxide anion after feeding with 0.12% MP showed higher ROI values. Therefore, dietary supplementation with different concentrations of mannoproteins resulted in an increase in survival and average surface area of shrimp midgut, as well as higher superoxide anion production in shrimp fed with 0.12% MP after infection with V. parahaemolyticus.