Author(s): YanBo WANG
The effectiveness on water quality, population density of bacteria, and shrimp production in ponds treated with commercial probiotics was tested in Penaeus vannamei ponds in Hai-yan, China. Six ponds with replicates for treatment and control were used. Results showed that the probiotics could improve the population density of beneficial bacterial flora, reduce concentrations of nitrogen and phosphorus, and increase yields of shrimp. The average counts of Bacillus sp., ammonifying bacteria, and protein mineralizing bacteria were found to be significantly higher in treated ponds compared to control ponds (P < 0.05). In control ponds, an increase in presumptive vibrios was observed and the average density was up to 2.09 × 103 cfu/mL, whereas that was only 4.37 × 102 cfu/mL in treated ponds (P < 0.05). The use of probiotics also significantly increased dissolved oxygen (P < 0.05) and reduced dissolved reactive-phosphorus, total inorganic nitrogen and chemical oxygen demand (P < 0.05). An average of 8215 ± 265 kg shrimp/ha was obtained in treated ponds with a feed conversion ratio (FCR) of 1.13 ± 0.05 and survival rate of 81.00 ± 6.25% compared with 4985 ± 503 kg shrimp/ha, 1.35 ± 0.12 and 48.67 ± 3.51%, respectively, in control ponds. This indicates that the addition of the commercial probiotics had a noticeable influence on water quality of shrimp ponds and shrimp production.