4
EMS IN SHRIMP
R
AQUA FEEDS
DECREASING THE MORTALITY IN EARLY MORTALITY SYNDROME by Dr Ron Cravens and Dr San “Chris” Ching, Amlan
esearch shows Calibrin products decrease the effects of biotoxins. For example biotoxins produced by Clostridium perfringens that are the cause of necrotic enteritis in poultry. Similarly, Early Mortality Syndrome (EMS) in shrimp is caused by biotoxins from Vibrio parahaemolyticus. Therefore, research was conducted to determine if Calibrin products would decrease the effects of this disease. Studies done in Thailand and the University of Arizona in the USA showed Calibrin products reduced mortality of shrimp challenged with V. parahaemolyticus or the toxins it produces.
Rapid move across SE Asia
The devastating disease soon to be known as Early Mortality Syndrome was first seen by Chinese shrimp producers in 2009. It rapidly moved to Vietnam, Malaysia and Thailand and in 2013 was first reported across the ocean in Mexico. The name Early Mortality Syndrome is very descriptive as its symptom is a high percentage of dead shrimp before 30 days of age. In 2013, a team of researchers at the University of Arizona found that the cause of EMS was the bacteria V. parahaemolyticus. Soon researchers in Thailand isolated, and researchers in Taiwan purified, biotoxins from V parahaemolyticus which are responsible for the damage to
the hepatopancreas of the shrimp, causing the high levels of mortality. Research shows Calibrin products decrease the effects of biotoxins. An example would be biotoxins produced from Clostridium perfringens, the cause of necrotic enteritis in poultry. Therefore, when it was resolved that EMS in shrimp was caused by biotoxins from V parahaemolyticus it was anticipated that Calibrin products might be able to help decrease the effects of this disease that was devastating the shrimp industry around the world. Experiments were conducted to determine the effects of Calibrin products on challenged shrimp.
In vitro / in vivo Toxin Binding – Thailand
These studies looked at how Calibrin products would interact directly with the V. parahaemolyticus toxins: ToxA and ToxB. Biotoxin binding and toxicity studies were performed by incubating increasing amounts of Calibrin (0, 31.3, 62.5, 250, and Table 1: Histopathology Scoring of Shrimp Treatment Control (no EMS)
Shrimp Number
EMS Grading1
Sampling Status
6
G0
Survivors
EMS Control
7
G2
Moribund
EMS + Calibrin-Z
8
G0
Survivors
1Grading system based upon severity of EMS from G0 (not detected) to G4 (severe infection). Survivors were assumed to have healthy status University of Arizona
54 | September | October 2016 - International Aquafeed