The purpose of this study was to evaluate the effect of Brachionus plicatilis and Navicula sp. addition on growth performance, Vibrio count, immunological responses and resistance to white spot syndrome virus (WSSV) of Litopenaeus vannamei in nursery biofloc system. The study was divided into two phases and four treatments were examined in the first phase: BFT (biofloc); BFT-N (addition of 10×10⁴ cells mL⁻¹ of Navicula sp.); BFT-B (addition of 30 org mL⁻¹ of B. plicatilis) and; BFT-BN (addition of 10×10⁴ cells mL⁻¹ of Navicula sp. and 30 org mL⁻¹ of B. plicatilis), all in triplicate and; the second phase included a viral challenge, also in triplicate. Shrimp (PL_10, 2 ± 0,01 mg) were reared in biofloc system (fertilized with inorganic and anaerobic and aerobic carbon process with a microbial mix), for 45 days at a density of 3000 shrimp m^-3, with controlled temperature, without water exchange and fed with commercial feed. The diatoms and rotifers were added every 10 days, and at the end, shrimp performance, water quality, Vibrio count and total hemocyte count were evaluated. After 45 days, 300 shrimp m⁻³ were challenged with WSSV (2.2 × 10⁷ copies of WSSV μL⁻¹ of DNA) for 9 days. The BFT-N, BFT-B and BFT-BN treatments had higher values of final weight (1.02 to 1.16 g) and yield (2.85 to 3.30 kg m⁻³) which were higher than the BFT (0.86 g and 2.46 kg m⁻³). There were no differences in water quality among treatments. Vibrio count from water samples was significantly lower at the end of experiment with significant decrease of non-sucrose-fermenting gram-negative bacteria. However, for hepatopancreas, the Vibrio count was significant higher at the end, however with significantly increase of sucrose-fermenting gram-negative bacteria (98 to 100%). There was no significant difference between the THC and hyalyne count for all treatments. Massive mortality rate was firstly achieved in BFT and BFT-B treatments in the second phase. However, all treatments reported complete mortality and WSSV infection was confirmed by nested-PCR and histopathologically, with lesions suggestive of WSD (presence of nodules and tissue deformations). The Navicula sp. and B. plicatilis addition contributed to better performance parameters of shrimp in the nursery biofloc system, although there was no significant effect on the WSSV resistance of shrimp. Absence of tissue degeneration in WSSV infected shrimp from BFT-N treatment indicated benefit of using diatoms under standardized conditions.

这项研究的目的是评估Brachionus plicatilis和Navicula sp。的作用。此外，在苗圃生物群系统中，南美白对虾的生长性能，弧菌计数，免疫应答和对白斑综合症病毒（WSSV）的抵抗力也很强。该研究分为两个阶段，在第一阶段检查了四种治疗方法：BFT（生物絮凝剂）；BFT-N（除了10×10的⁴细胞毫升^-1的舟形藻。）; BFT-B（添加30 org mL ^-1的B. plicatilis）和；BFT-BN（添加10×10 ⁴细胞mL ^-1的Naviculasp。和30 org mL ^-1的B. plicatilis），一式三份；第二阶段包括一式三份的病毒挑战。虾（PL _10， 2±0,01毫克）在生物絮凝系统中饲养（受精与无机和厌氧和好氧碳处理与微生物混合），45天以3000虾米的密度^-3，具有受控温度，无需换水，并用商业饲料喂养。每隔10天添加一次硅藻和轮虫，最后评估虾的生产性能，水质，弧菌计数和总血细胞计数。45天后，用WSSV攻击了300只虾米^-3（2.2×10 ⁷份WSSVμL ^-1DNA）9天。所述BFT-N，BFT-B和BFT-BN处理具有的最终重量（1.02〜1.16克）和产率的较高的值（2.85 3.30公斤米^-3），其比所述BFT更高（0.86克和2.46公斤米^{- 3}）。各处理之间水质无差异。在实验结束时，水样中的弧菌计数显着降低，非蔗糖发酵革兰氏阴性菌明显减少。但是，对于肝胰腺，弧菌计数在结束时显着更高，但是蔗糖发酵革兰氏阴性细菌显着增加（98％至100％）。在所有治疗中，THC和透明质酸计数之间无显着差异。在第二阶段中，BFT和BFT-B治疗首先达到了大规模死亡率。但是，所有治疗均报告完全死亡，并且通过巢式PCR和组织病理学证实了WSSV感染，病灶提示为WSD（存在结节和组织变形）。该舟形藻。和B. plicatilis尽管对虾的WSSV抗性没有显着影响，但添加添加有助于虾在苗圃生物絮凝系统中获得更好的性能参数。BFT-N处理的WSSV感染虾没有组织变性，这表明在标准化条件下使用硅藻有好处。