Abstract The aim of this study was to evaluate Viligen® NE (Alltech®, USA) as a feed additive for Penaeus vannamei reared in a biofloc system during the nursery phase, focusing on growth performance, intestinal microbiological analysis, and resistance tocold challenge. Shrimp post-larvae (41 mg) were fed for 6 weeks with four experimental diets: (a) 0.5 g Viligen® NE kg⁻ 1 , (b) 1 g Viligen® NE kg⁻ 1 , (c) 2 g Viligen® NE kg⁻ 1 , and (d) a control diet (0 g Viligen® NE kg⁻ 1 ). The experiment was conducted in quadruplicate, totaling 16 experimental tanks, with a stocking density of 2000 post-larvae m⁻ 3 . Shrimp growth performance parameters were positively influenced by the inclusion of Viligen® NE in the diet. Polynomial regression indicated an optimal inclusion level of 1.17 g kg⁻ 1 for maximizing specific growth rate and weight gain. Additionally, supplementation at 1 g kg⁻ 1 enhanced shrimp resistance to cold challenge. However, no significant differences were observed in intestinal counts of total heterotrophic bacteria or Vibrio spp. among treatments. In conclusion, dietary supplementation with Viligen® NE at an optimal level of 1.17 g kg⁻ 1 improved growth performance, and 1 g kg⁻ 1 enhanced cold challenge resistance of nursery-phase shrimp reared in a biofloc system.

Abstract The potential replacement of fishmeal using fermented abalone viscera meal in Oreochromis mossambicus feeds was explored. Five diets were prepared by adding fermented abalone viscera meal at 0% (control), 10%, 20%, 30%, and 40% to replace fishmeal. Diet 6 constituted the fermented abalone viscera meal only. The diets were then denoted as FAV1, FAV2, FAV3, FAV4, FAV5, and FAV6, respectively. Diets (each) were assigned at random to triplicate tanks of O. mossambicus fingerlings (7 ± 1.4 g) and fed for 6 weeks. Specific growth rate was higher in the FAV4 (1.51 ± 0.09), FAV5 (1.74 ± 0.05), and FAV6 (1.68 ± 0.02) diets than in the FAV1 (1.05 ± 0.09), FAV2 (1.12 ± 0.10), and FAV3 (1.21 ± 0.07) diets. Feed intake and weight gain were also higher in the FAV4, FAV5, and FAV6 diets compared to the FAV1, FAV2, and FAV3 diets. Feed conversion ratio was significantly lower ( P < 0.05) in the FAV4 (2.73 ± 0.31), FAV5 (2.63 ± 0.28), and FAV6 (2.65 ± 0.19) diets than in the FAV1 (3.34 ± 0.67), FAV2 (3.29 ± 0.54), and FAV3 (3.18 ± 0.38) diets. However, among the viscera inclusion levels (FAV2-FAV5) and the FAV6 diet, the highest growth performance was noted in the FAV5 group. The highest apparent digestibility coefficient values were noted in FAV4 (91.27 ± 3.39%), FAV5 (92.52 ± 3.44%), and FAV6 (92.24 ± 3.82%) while lower values were recorded in FAV1 (86.42 ± 3.11%), FAV2 (86.04% ± 3.18), and FAV3 (87.21 ± 2.96%). The addition of the fermented viscera to the O . mossambicus diets did not affect villi height and width nor goblet cells count. In addition, liver histology was not impacted by the use of the fermented abalone viscera meal across treatments (no enlargement of hepatocytes, sinusoids, or vacuolation). The results indicated that activities of protease, amylase, and lipase were higher in the FAV4, FAV5, and FAV6 diets as opposed to the FAV1 and FAV2 and FAV3 diets. The improved growth performance and enzyme activities in the FAV4, FAV5, and FAV6 diets show that the abalone viscera can be utilised as a protein source in O . mossambicus .