The use of belt feeders in super intensive culture of Pacific White shrimp Litopenaeus vannamei in BFT systems  

Dariano Krummenauer*, Aline Bezerra, Carlos Gaona, Luis H. Poersch and Wilson Wasielesky Jr.
 
Graduate Program in Aquaculture, Institute of Oceanography
Universidade Federal do Rio Grande (FURG), Rio Grande, RS, Brazil
darianok@gmail.com  

Currently, the shrimp culture has been directed to systems that minimize the use of water. The biofloc technology culture system (BFT) contributes to the water quality, through the removal of nitrogen compounds, supplements the shrimp diet and allows the use of high stocking densities. In this system, the use of automatic feeders can minimize reduction of dissolved oxygen as well to overcome labor problems. The aim of this study was, evaluate the use of belt feeders in super intensive culture of Pacific White shrimp Litopenaeus vannamei in BFT systems.

A 60 day-trial was conducted at the Marine Station of Aquaculture, University of Rio Grande, Rio Grande do Sul State, Brazil. After nursery, Pacific white shrimp (1.06g ±0.58) juveniles were stocked at 400/m3 in a nine-35 m³ lined raceways greenhouse enclosed. Three treatments (three replicates) were tested: T1, by hand (three times per day); T2, by hand + 12-hour belt feeder (BF) (three times per day) and T3, 24-hour belt feeder (BF). To accelerate the development of the bioflocs, inoculations of 10% of biofloc-rich water were inserted in order to microorganism's succession and improve water quality. Furthermore, molasses was added when the total ammonia levels reached 1.0 mg L-1. Water temperature, salinity, dissolved oxygen (DO), pH, TA-N, NO2-N, NO3-N and Alkalinity were daily analyzed. Settleable solids (ml L-1) were measured three times per week using an Imhoff cone with readings recorded after 15-20 min. Water was collected to measure the total suspended solids (TSS) and kept below 500 mg.L-1. The results were analyzed by one-way analysis of variance (ANOVA) and Tukey's test (α = 0.05).

The water quality parameters were not influenced by the treatments (P>0.05) and were not limiting for shrimp survival and growth (Table 1). Shrimp survivals were not influenced (P>0.05) by the treatments. The growth parameters were also not different among treatments,  (P>0.05), except FCR (P<0.05) (Table 2). Results suggest that automatic feeders can be incorporated as a important tool in super intensive BFT system in raceways.