EFFECT OF AN ALGAE-CLAY BASED BIOCATALYST ON THE DIGESTIVE AND GROWTH PERFORMANCE OF JUVENILE SHRIMP (Litopenaeus vannamei)

Maarten Jay van Schoonhoven*, Jintasataporn Orapint
 Olmix, Arnhemsestraatwerg 8, 6880 AG, Velp, The Netherlands
 mjvanschoonhoven@olmix.com

Although, shrimp production has boomed during the last decades, reaching more than 4 million tons in 2012, farmers have had to deal with infectious diseases, to ensure their production. One of the most important diseases is Vibriosis, killing shrimps all along the production cycle. Though Vibrio bacteria occur naturally in the shrimp environment, Vibriosis can occur in a context of an imbalanced environment and may cause heavy mortality of reared shrimp. Limiting Vibrio contamination can be achieved with good management practices or use of antibiotics and chemotherapy, but these have limits when it comes to environmental hazards and spreading of antibiotic resistance. Alternative methods focus on a natural digestive balance of shrimp in order to prevent the colonization of Vibrio in the intestine. In this context, Olmix developed a product, based on a new technology associating clay and algae extracts, aimed at improving shrimp performance through boosted digestive enzyme activity and improved digestive balance. The aim of the present study was to evaluate the effect of this algae-clay mix (MFeed+) supplementation on the digestive and growth performance of L. vannamei shrimp.

Three hundred and seventy-five shrimps (6.3±0.2g weight) were distributed in fifteen five-hundred-liter glass tanks, containing twenty-five shrimps each. After a seven day period of acclimatization when all shrimp were fed the basal diet, tanks were randomly allotted to one of three treatments (five replicates per treatment), supplemented with different levels of algae-clay mix (0, 0.1 and 0.2% of the basal diet). Growth performance parameters and mortality were recorded during the sixty days of supplementation. Vibrio bacteria were counted in the hepatopancreas and the intestine after sixty days of supplementation as a marker of digestive health.

Results showed a significant improvement of Feed Conversion Ratio for shrimps supplemented with 0.1 and 0.2% of algae-clay mix in comparison with the control (respectively -13 and 14%, P<0.05). Specific Growth Rate tended to be higher as well in these groups. The survival rate was highly significantly increased in the supplemented groups compared to the control, with a possible dose effect (+17% and +23%, respectively for shrimps supplemented with 0.1 and 0.2%, P<0.01). This is in line with the histopathology results, showing a decreased level of Vibrio in the hepatopancreas in the group supplemented with 0.2% of algae-clay mix (-62%, P<0.05).

In conclusion, this study highlighted the capacity of the algae-clay mix to improve the digestion of shrimps and to secure digestive health by limiting Vibrio colonization in the digestive tract, resulting in better growth performance.