LACTOBACILLUS PARACASEI SUBSP. TOLERANS ISOLATED FROM JENYN`S SPRAT (RAMNOGASTER ARCUATA) AS PROBIOTIC FOR JUVENILE RAINBOW TROUT (ONCORHYNCHUS MYKISS) (WALBAUM, 1792)

MARÍA GABRIELA SICA; ANDREA LOPEZ CAZORLA; LORENA BRUGNONI; PATRICIA MARUCCI; MARÍA AMELIA CUBITTO

San Miguel de Tucuman

Simposio; IV Simposio Internacional de Bacterias Lácticas; 2013

CERELA (CONICET)

Rainbow trout (Onchorhynchus mykiss) is the predominant species reared in Argentine aquaculture. The feed accounts for is the main cost of production of this specie, and therefore the feed quality and feeding strategy are of utmost importance. Slight improvements in feed efficiency can result in an important diminution of the production costs and feed wastes that would otherwise alter the water quality. The use of probiotics in aquaculture is presented as an excellent choice not only for disease control, but also as growth promoters of the organisms. The beneficial effect of the feed efficiency and growth promotion when these strains are given as dietary supplements, have attracted increasing interest in recent years. The aim of this study was to evaluate the effects of a Lactobacillus paracasei subsp toleransF2 strain on growth parameters of juvenile rainbow trout. This strain was isolated from the gastrointestinal tract of Ramnogaster arcuata (nv: Jenyn?s sprat), a fish that spends whole life cycle in Bahía Blanca Estuary. The feeding experiment was conducted in 500 L fibreglass tanks, each provided with 98% re-circulated aerated freshwater at a rate of 300 l h. The water temperature was maintained at 14 ± 2 ºC, oxygen levels above 80 % saturation. Fish were held under natural photoperiod of latitude 39 ºS. and treatments were conducted in triplicate One system was employed for the probiotic treatment (commercial feed supplemented with the strain F2) and the other was used as control (commercial feed). During the 66 days of experiment there was no evidence of negative effects of strain F2 in rainbow trout because no pathology and normal behavior was observed. No significant differences in the survival in both systems were detected. F2 fed fish showed a mean weight gain of 228% and 211 % in the control diet fed fish. Significant differences in the specific growth rate and feed conversion ratio in the treatment group, compared to the control were detected. The improvement in feed efficiency, results in a diminution of the amount of balanced food required to obtain the desired weight. These values have a significant impact on the costs when the amount of food is scaled to the production levels. The results of this study would indicate that F2 could be used as a probiotic in juvenile rainbow trout culture.