Shrimps are unique in that they do not have adaptive immunity; therefore, they rely on innate immune responses to protect them from pathogenic infection. The lack of acquired immunity means that vaccination cannot be used as a prevention strategy in shrimp production. Rather, optimizing innate immunity – including the integrity of the intestine and barrier function – is an important strategy to preventing disease. In this regard, an interesting emerging concept is the use of feed supplements that can support the immune system. Of particular interest are botanical supplements that can improve non-specific (innate) immune responses and recovery of disease when an outbreak does occur. Botanical supplements containing actives that have immunomodulatory properties are promising candidates for prevention. Therefore, the plants extract present in this botanical tested have the potential to not only prevent disease but also to increase the animal’s ability to cope if and when disease does strike.
The objective of this experiment was to evaluate the efficiency of a botanical feed supplement on disease resistance of pacific white shrimp (Litopenaeus vannamei) challenged with vibrio, V. parahaemolyticus. Five treatments were considered, depending on botanical inclusion level (g/ton): Control; T1-AVT100; T2-AVT150; T3-AVT200 and T4-AVT250. After 60 days of feeding trial, 8 shrimps per treatment were injected with vibrio at 106 CFU/mL and were kept under observation for 10 days post infection.
Based on microbiological analysis, it was confirmed that mortality of shrimp was caused due to V. parahaemolyticus infection. Treatments T2-AVT and T4-AVT had a lower cumulative mortality percentage compared to the Control group (Fig. 1). That could be explained due the positive effect on immunomodulation of shrimps fed with the botanical supplement.
Relative percentage survival increased proportionately with inclusion level of botanical immunomodulator in the diet (Fig. 2). Shrimps in the treatments T2-AVT150 and T4-AVT250 had higher relative percentage survival.
Botanical immunomodulator proved to be efficient in reducing mortality and increasing survival in shrimps challenged with Vibrio parahaemolyticus at inclusion dose of 150 g/ton of feed.