SHRIMP (L. VANNAMEI) CHALLENGED WITH EMS/AHPND CAUSING BACTERIA AND THE EFFICACY OF CLAY, ALGAE AND COPPER PREMIX ON THE HEALTH PERFORMANCE
Over the years, the shrimp industry has had to deal with its share of diseases, which is a natural development in the evolution of the production of live animals. One of the more recent disease outbreaks which has had a very strong impact in the shrimp industry is AHPND, also known as EMS. Its slow but steady progress started in Asia where it spread into various countries, such as Vietnam, Malaysia and Thailand. EMS eventually made its way into the Latin American markets where it has also had a strong impact in the industries there.
Diseases are a natural part of animal production and the industry normally finds a way to deal with them. Generally past experiences in dealing with disease outbreaks are the first approach. Often small adjustments are developed to manage the disease. These tend to lead to preventive measures to be taken such as biosecurity and adapted culture techniques.
Preventive measures still allow for exposure to microbial environments, but also reduce risks of disease outbreaks. Improving shrimp gut health is a very effective method of preventing pathogens affecting the digestive tract. Use of clays, algae and copper in feed can influence the intestinal mucosa integrity and the microflora balance in the gut.
The present study consisted in evaluating the effect of a commercial premix based on clay (Bentonite), algae (Ulvan sp) and copper on the health performance of shrimp (L. vannamei) after a challenge test with EMS causing bacteria (V. parahaemolyticus). PL5 shrimp, testing negative to common shrimp diseases (including V. parahaemolyticus) by PCR method, were reared following 4 treatments. T1 was the negative control, T2 the positive control, T3 had a continuous inclusion of 0,2% MFeed premix in the diet and T4 had a continuous inclusion of 0,4% MFeed premix. At PL25 shrimp were challenged via an immersion bath with V. parahaemolyticus causing EMS. Survival rates were monitored daily over a 14 day period until conditions were stable. First mortalities were observed 9 hours post challenge in the positive control, compared to 24 and 36 hours in the T3 and T4 respectively. Also preventive use of MFeed premix showed a 55% and 73% increase in overall survival for T3 and T4 respectively, when compared to the positive control group T2.
In conclusion, feed supplemented with the clay, algae and copper premix used in this trial can significantly increase survival rates of shrimp challenged with EMS causing bacteria when applied in a preventive manner.