EFFECT OF AN ALGAE-CLAY BASED BIOCATALYST ON THE DIGESTIVE AND GROWTH PERFORMANCE OF NILE TILAPIA (Oreochromis niloticus) FED TWO DIETS WITH DIFFERENT LEVELS OF FISHMEAL  

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

Fishmeal has been a preferred ingredient in aquaculture feeds due to its well balanced nutritional composition and its easy digestibility. With pressure on wild catch and a stagnating supply of fishmeal, alternatives are becoming increasingly important in aquafeed. The use of plant raw materials are becoming the trend in replacing fishmeal in aquafeed formulation. However, plant ingredients as well as other alternative ingredients, have to be used carefully taking into account the digestibility and bioavailability of nutrients for the target aquatic species. Much attention is given to the combination of ingredients to fulfill the nutritional requirements of the aquatic species but the digestibility and nutritional bioavailability is sometimes more difficult to achieve. In this context, Olmix developed a product, based on a new technology associating clay and algae extracts, aimed at improving fish performance by boosting digestive enzyme activity and improving 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 Nile tilapia.

720 fish (6.58g weight) were distributed in thirty six-240L glass tanks, at a density of 40fish/m2. After a seven day period of acclimatization when all fish were fed a basal diet, tanks were randomly allotted to one of six treatments (six replicates per treatment); two diets (20% fishmeal and 5% fishmeal), each supplemented with different levels of algae-clay mix (0, 0.1 and 0.2% of the basal diet). Growth performance and health parameters were recorded during the twelve weeks of supplementation.

Results show a, dose related, increased growth performance in fish when supplemented with the algo-clay mix. A low fishmeal diet with 0.2% supplementation can achieve equal or better growth performance when compared to a high fishmeal diet. FCR tended to improve and health parameters showed improvement with the algo-clay mix supplementation. Liver and gut morphology also benefited from the algo-clay mix.

Conclusion, supplementing tilapia diets with algo-clay resulted in improved digestion, health and significant increases in growth performance in fish fed high and low level fish meal diets.