EFFECTS OF DIFFERENT SOIL TYPES ON AZOLLA Anabelae CULTURE AS A PROTEIN SOURCE REPLACER IN FISH DIETS

The increase in costs and demand of protein from conventional resource necessitates fish farmers and hatcheries manager to incorporate cheap and locally available ingredients in fish diets. Among protein plant sources, Azolla (Anabelae) species seem to be good replacer of protein from expensive sources such as fish meal and fish oil. It contains high crude protein content (13%-30%) and essential amino acid (EAA) composition (rich in lysine) than most green forage crops and other aquatic macrophytes. The present study was conducted to determine the effect of different soil types on Azolla (Anabelae) culture as a protein sources replacer in fish diets.

A 3-week culture trial was conducted in a 4 HDPE sheet pits (6M X 1M X 0.2M). Each two pits laid with 25kg of red and fertile lake soil respectively, after nutrients composition analysis in the soils (Table 1). All four pits were filled with water to a height of 20cm and fertilized with 2kg of cow dung slurry and 30gm of Single Super Phosphate. One day after fertilization, 200gm fresh culture of Azolla (Anabelae) species collected from Tamil Nadu Veterinary and Animal Science University were inoculated in each pit. All four pits were left for rapidly growth and fertilization were repeated after every 6 days with the same quantity of cow dung slurry and Single Super Phosphate for 3 weeks.

After culture period, each pit was harvested with a scoop net having a mesh size of 1mm, weighed, dried on sunlight for three days and weighed again before milled.

After a culture period of 3 weeks, lake fertile soil had significantly (P<0.05) higher wet weight, dry weight and lower cost of production compared to red soil (Table 2 & 3). These results indicate that a lake fertile soil can be used for higher production of Azolla at low costs which will optimize growth of fish and reduce cost of production.