EVALUATION OF AN EXPERIMENTAL PROBIOTIC IN A NURSERY SYSTEM TO DETERMINE THE EFFECT OF GROWTH AND SURVIVAL OF WHITE SHRIMP Penaeus vannamei
The white shrimp aquaculture in intensive systems is a highly profitable activity in northeastern Mexico. However, in recent years, the presence of different diseases has generated severe economic losses, affecting the supply chain. Therefore, it is important to explore production alternatives with an economic, social and environmental sustainability approach. Among the technologies incorporated, we found high-density units or nursery systems with minimal water exchange and use of a microbial consortium (probiotics and BFT biofloc technology).
The present study was carried out at a commercial shrimp farm located in southern Sonora, Mexico, and aimed to evaluate the performance of an experimental probiotic in a nursery system of white shrimp postlarvae (Penaeus vannamei). The trial was carried out in a raceway pond covered with liner and greenhouse dome, with an area of 1,440 m2, 1.20 m of depth and a water volume of 1,728 m3; which was stocked with a population of 4,545,000 organisms (PL 12 with an average weight of 3.5 mg). During 26 days the shrimp postlarvae were fed every 2 hours at 10% average body weight (ABW) until obtaining a suitable size (approx. 300 mg) for their transfer into the ponds.
The preparation of the probiotic was developed with lyophilized bacteria of the genus Bacillus sp. (strains 13L, 36R, 42), which were obtained from marine environments of the coast of Sonora. This group of bacteria were preliminary evaluated in laboratory with in vitro and in vivo tests showing good results. For the preparation and activation of the probiotic it was added molasses, bran, urea, yeasts and constant aeration; the process was carried out in 3 phases of 18-24 h of incubation each, and in volumes of 10, 100 and 1,000 L. The last scaling phase was used for the daily application in two modes: 150 mL/kg for feed (mixing before feeding) and 200 L directly to culture water. To determine the effect of the consortium on the shrimp nursery system, daily biometrics, digestive tracts analysis, pigmentation and behavior activity were performed, as well as monitoring physicochemical water parameters (disolved oxygen, temperature, pH, salinity, nitrite, nitrate, ammonia).
The trial results are indicated in Table 1. The shrimp postlarvae reared in the nursery system with the experimental probiotic consortium and normal management, showed a good survival rate, growth and health, with proper development and weight gain. However, water quality was compromised during the final phase due to high temperatura (35oC) and shrimp biomass. The use and application of the experimental probiotic in feed and water worked as a management tool during the shrimp culture, however more studies and field trials in other systems as well as growout ponds are recommended.
