The influence of probiotic bacillus on health, survival rate and growth of Rainbow Trout (Oncorhynchus mykiss) fry in exploitation of Daphnia meal

Objective: The aim of this study was to use Probiotic Bactria in diets of Rainbow Trout larvae to increase health rate, growth parameters, and survival rate during a culture period. One of the important aims of using probiotics is to increase survival rate. Due to extra cellular substances of probiotics, they can lead to an increase of the digestibility of food in fish larvae, and so causes an increase of growth performance and feeding efficiency in larvae of these fishes. So the study examined the above said effects on Trout larvae by measuring of growth parameters and survival rate. Method & Materials: Five probiotic bacteria were used in this experiment which was conducted in a completely randomized design with four treatments and control. Five diets were prepared from Biomar and meal of Daphnia. Experimental diets were supplemented with the probiotic bacillus in levels of 1×106, 2×106, 3×106, 4×106 CFU/g and control diet were prepared. The trout fry were fed on the base of the 10 percent of their body weight for 6 times per day for a period of 30 days. In the termination of experiment, the growth parameters, Survival and health rates of fish were measured. Results & Conclusion: The total length, body weight, survival and health rate, weight gain and growth rate of trout fry, were affected by bacterial supplemented diet in. The experimental treatments maximum body weight (2.44 g) and survival rate (95%) was obtained in treatment diet D2 (2×105 CFU/g). The specific growth rate (3.63), average daily growth (7.16), food conversion efficiency (62.83), protein efficiency ratio (0.90), and Lipid efficiency ratio (3.22) in trial 2 treated with. The probiotic bacillus, were significantly higher than the control (p<0.05) best performance of fish in terms of growth performance, health and survival rate was recorded at the bacterial supplementation of 2×105 CFU/g in diet. A positive significant correlation was obtained between the levels of probiotic (p<0.05). The bacillus in diets and growth parameters, survival and health rate results of this investigation will be helpful in formulation of practical diets for trout culture. Suggesting that the addition of probiotics reduced the mortality of fishes in cultivation systems.This study showed that different levels of probiotic bacillus could have different effects on growth and survival rate in trout fry.

کلیدواژه ها:

Probiotic ، Daphnia ، supplemented diet ، growth parameters ، survival