محمود نفیسی بهابادی

A 56-day study was carried out to examine the addition of live foods a biofloc technology (BFT) system on Penaeus vannamei postlarvae performance (PL25, initial weight: 0.15 g). Four treatments were designed, including 1) control: PL were only fed with an artificial diet (38% crude protein; 9%, crude fat) in a clear seawater system; 2) CBC: inclusion of copepod (Calanopia elliptica, 0.2 organisms/mL) in the BFT; 3) ABC: inclusion of Artemia nauplii (Artemia franciscana, 0.1 organisms/mL) in the BFT and 4) RBC: inclusion of rotifer (Brachionus rotundiformis, 0.3 organisms/mL) in the BFT. Postlarvae were stocked into twelve tanks that contained 200 L seawater (70 PL/tank). The mean values for water temperature, salinity, and dissolved oxygen were 31.0 °C, 36 ppt, and > 5 ppm, respectively. Total ammonia and nitrite nitrogen in BFT system were lower than the control. The highest and lowest weight gain (4296.5 vs. 3242.2%) was in CBC and the control, respectively. The best feed conversion ratio (FCR) value (1.22) was in CBC group. The gut’s epithelial cell length in BFT groups was higher than the control. The highest total hemocyte count (152.2 × 105/ mL) and total plasma protein (122.31 g/L) were in CBC group (P < 0.05). The relative abundance of lysozyme, prophenoloxidase, superoxide dismutase, and catalase genes mRNA transcript in the hepatopancreas of shrimps reared in the BFT that supplemented with different live foods was higher than the control (P < 0.05). According to the findings of the present study, the inclusion of Calanopia elliptica at a density of 0.2 organisms/ mL in BFT led to higher growth rate, better FCR, and greater immunocompetence in P. vannamei compare to rotifer and Artemia nauplii.