The performance of beneficial microorganisms in promotion of health, survival rate and production of cultivable fish larvae

Objective: A live beneficial microbial adjunct has a profitable effect on a host by modifying the host-associated or ambient microbial community, by improving nutritional value, enhancing the host’s response towards disease, or by improving the quality of its ambient environment. ptimization of microbiological factors can reduce the heavy mortalities that often occur during the rearing of aquatic animals and can promote their cultivation performance. Therefore, using beneficial microorganisms as probiotics investigated as an important strategy by biocontrol and bioencapsulation of live foods for promotion of health and production in cultivation systems for fish larvae. Method & Materials: A number of recent researches by the authors, indicated that some beneficial bacterial and yeast as a live microbial feed supplement and via bioencapsulation of live food (animals for feeding fish) as Artemia urmiana, Daphnia magna and Daphnia sp. The probiotic yeast, Saccharomyces cerevisiae and probiotic bacillus, Bacillus licheniformis, B. subtilis, B. polymixa, B. laterosporus, B. circulans and lactic acid bacteria, Lactobacillus plantarum, L. delbrueckii subsp., L. acidophilus and L. rhamnosus, were used in these studies. The cultivable fish larvae, Acipenser persicus, Acipenser nudiventris, Huso huso, Oncorhynchus mykiss, Hypophthalmichthys molitrix and Cyprinus carpio carpio were employed in these trials feeding. Results & Conclusion: Live preys as important vectors carried the probiotic bacteria to the digestive tract of cultivable fish larvae. The probiotics through improving the intestinal microbial balance had beneficial effects on elevation of survival rate, resistance in return for pathogens, feeding efficiency, growth and production performance, tolerance of fish larvae against environmental conditions in cultivable fish larvae. The results indicated that to what extend the introduction of beneficial bacterial strains can be profitable in increasing the adaptation and enhancement of health of this aquatic animals. Some of these probiotics significantly promoted leveles of crude protein, crude lipid, crude energy, ash and carcass dry matter in experimental treatments in comparison with control treatment. Also the food conversion efficiency, protein efficiency ratio, lipid efficiency ratio, energy efficiency ratio, protein productive value and lipid productive value increased in treatments under the influence of probiotics. These probiotic bacilli increased the digestive enzymes as total amylase, total lipase and total protease in digestive tract of the Persian sturgeon (Acipenser persicus) larvae. Theses studies also showed that different levels of probiotics could have different effects on the cultivable fish larvae. The results of these investigations will be helpful in larviculture of cultivable fish in hatcheries and in rearing pond.

کلیدواژه ها:

Optimization ، Probiotic ، Bioencapsulation ، mortality ، Adaptation