SMARTSHIELD CONCEPT IN SHRIMP FEED AGAINST BACTERIAL DISEASES IN WHITE LEGS SHRIMP Litopenaeus vannamei
Acute Hepatopancreas Necrosis Disease (AHPND) is a bacterial disease which affect early stages of Litopenaeus vannamei, due to Vibrio parahaemolyticus, that has genes of both toxins, PirA and PirB (Li et al., 2017). Functional feeds are one of the key alternatives against bacterial disease and specifically against AHPND. A combination of organic acids, fermented products based on yeast, hepatoprotectors and nucleotides were assessed against bacterial infection, caused by V. parahaemolyticus. Two trials with shrimp (L. vannamei) were performed during 2018 in the Global Innovation Center (GIC) and Technological Application Center (TAC), Elk River and Bac Lieu TAC in Vietnam, respectively. In the first trial, performed in Elk River, 600 shrimps, average weight of 0.5 g/ shrimp, were allocated in 20 tanks, 30 shrimps/tank. Four treatments were considered for groups of shrimp allocated in 4 tank each, where A was control feed, B the low dose of SmartShield, C medium dose of SmartShield and D was control feed without challenge. Shrimp fed the experimental feeds for 3 weeks. After this period all groups of shrimps were challenge with V. parahaemolyticus, except group D. Mortality was recorded daily until 5 days post infection (Figure 1).
For the second trial done in TAC Vietnam, 6.400 shrimp with an average weight of 2.5 g/shrimp, were allocated in 32 hapas, 200 shrimps/hapa located in one pond of 400m2. Four treatments with 8 replicates were considered, where A was the group of shrimps fed with control feed, B was the group fed with low SmartShield, C was fed with medium level of SmartShield and D was the group fed with high level of SmartShield. Shrimps fed experimental feeds during 61 days. Mortality was recorded at the final (Figure 2).
Shrimps feds with medium level of SmartShield in feed in both trial obtained an average survival of about 60% which represented between 7 to 12% higher survival compared with control groups.
