Effect from Combinations of Yucca schidigera extract with Bacillus Strains on the Growth of White Leg Shrimp (Penaeus vannamei), Density of Vibrio sp., and on the Ammonia and Nitrite Content of Culture Water

The water quality including toxic gas parameters and Vibrio density is a serious problem in intensive shrimp culture. Yucca schidigera extract and Bacillus sp. are considered as a practical solution to improve the water quality. The aim of our study was to determine the effect of combination of Yucca schidigera extract and Bacillus spp. on total ammonia nitrogen (TAN) and nitrite contents, Vibrio count, and the growth performance of white leg shrimp (Penaeus vannamei). Shrimp (PL12) were assigned to seven treatments (triplicates) including treatments with combination of yucca extract and single strain of Bacillus (AY, B2Y, B3Y), combination of yucca extract and Bacillus consortium (ABBY), yucca extract only (Y), Bacillus consortium (ABB), and control treatment (C). Vibrio count was carried out by the spread plate technique every 7 days. TAN and nitrite contents were determined by using sodium nitroprusside, and sulphanilic acid with N-(1-naphthyl) ethylenediamine, respectively, at 24 hours and 168 hours after adding Bacillus strains and yucca extract. The shrimp growth parameters include the final biomass, final body weight (FBW, g), weight gain rate (WGR, %), survival rate (SR, %), and feed conversion ratio (FCR) were recorded after 5 weeks. The results showed that the water quality (0.073 – 0.179 ppm of TAN, 0.187 – 0.934 ppm of nitrite, and Vibrio count of 2.552 – 3.038 log CFU/ml) of tanks treated with combination of yucca extract and single strain of Bacillus (AY, B2Y, B3Y) or Bacillus consortium (ABBY), and Bacillus consortium (ABB) was significantly controlled compared to the control and yucca extract only treatments. The ABBY treatment most significantly improved the shrimp growth parameters (FBW, biomass, WGR, FCR, and SR – 0.424 ± 0.010 g, 40.202 ± 1.510 g, 14048.902 ± 328.756 %, 1.100 ± 0.040, and 94.667 ± 1.856 %, respectively) compared to the other treatments. Overall, our study concluded that the combination of yucca extract and Bacillus consortium could control water quality (0.036 – 0.105 ppm of TAN, 0.187 – 0.604 ppm of nitrite, and Vibrio count of 2.553 – 2.624 log CFU/ml), reduce 46.49% of FCR and significantly increase the growth performance (approximately 92.73% of FWB, 163.19% of biomass, 93.93% of WGR, 46.49% of FCR) of P. vannamei (PL12) with density of 100 individuals/100L.