EFFECTS OF FEED PROBIOTIC LEVELS ADMINISTERED TO SHRIMP IN A BIOFLOC, NO EXCHANGE TANK SYSTEM

Susan Laramore*, Tzachi Samocha and Jutta Kesselring
 Harbor Branch Oceanographic Institute at Florida Atlantic University
 Aquaculture and Stock Enhancement Program
 5600 US 1 North
 Fort Pierce, FL 34946 USA
 slaramo1@fau.edu

The incorporation of probiotics in feed can contribute to overall health by increasing immune function which may in turn improve production. The present study examined the effects of topdressing shrimp feed (Zeigler HI-35) with Aquastar®, a probiotic manufactured by Biomin, Inc., on shrimp reared in a biofloc tank system. A four factorial random block design (0, 2, 3, and 5 g/kg) trial was conducted in 1.13 m3 (1.45 m dia) cylindrical HDPE tanks operated with air-driven floc circulation systems. Biofloc from the HBOI-FAU IMTA ex-situ bioreactor (16 L) was used to inoculate the culture medium and one hundred 1.5 g shrimp were stocked (88.5/m3) in each tank. Tanks were maintained with no water exchange and only freshwater was added to offset evaporation losses. Feed was delivered 24/7 using belt feeders. Growth was assessed weekly while survival, growth, and FCR were determined at the study termination (12 weeks). Water quality parameters were measured twice daily (DO, temperature, salinity), daily (pH, SS), or twice per week (TSS, TAN, NO2, NO3). Water samples were collected weekly and plated in triplicate on TCBS media. At trial termination water and shrimp intestines were plated onto Marine agar, TCBS, and MacConkey's agar.

Shrimp reached an average weight of 23 g with no statistically significant difference (P = 0.25) between treatments (Table 1). Although survival was higher and FCR was lower in the treatment group containing higher levels of probiotic, differences were not significant (P = 0.056, P = 0.060). There was no significant difference between Vibrio populations in water collected from the various treatment groups, however enteric bacterial counts were higher in treatments without probiotic (P = 0.045). There was no significant differences between the concentration of Vibrio and enteric bacteria in shrimp from the different treatments, although on average shrimp from the control treatment group had a higher percentage of pathogenic Vibrio and a higher percentage of lactose fermenting colonies. Taxonomic identification of bacteria has yet to be conducted.