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<p>Immunostimulants like seaweed can significantly enhance the immune response and disease prevention in aquatic animals. These substances boost fish resistance to infections by strengthening the nonspecific immune system, thereby improving overall health and pathogen combat capabilities. This study investigated the effects of the brown macroalga <i>Sargassum ilicifolium</i> extract on Asian seabass (<i>Lates calcarifer</i>), including growth, mucosal and serum immune responses, serum biochemical markers, bactericidal activity in serum and mucus, digestive enzyme activity, and resistance against <i>Streptococcus iniae</i>. A total of 360 Asian seabass with an average weight of 50.41 ± 1.08 g were divided into four treatment groups, each with three replicates. The fish were fed&#xa0;<i>S. ilicifolium</i>&#xa0;extract at concentrations of 0%, 0.5%, 1%, and 2% for eight weeks. Results showed that growth parameters, final weight, weight gain percentage, and specific growth rate increased significantly at 1% and 2% levels compared to the control group (<i>P</i> &lt; 0.05). The food conversion ratio also decreased significantly with these concentrations. Immune parameters such as serum and mucus bactericidal activity, mucus lysozyme, and immunoglobulin levels were significantly enhanced at the 1% and 2% levels (<i>P</i> &lt; 0.05). Furthermore, digestive enzymes like alpha-amylase (1% and 2%), trypsin (2%), and lipase (1% and 2%) showed significant increases after eight weeks of administration (<i>P</i> &lt; 0.05). Following the feeding period, fish were challenged with&#xa0;<i>S. iniae</i>, revealing survival rates of 15% in the control group, 25% in the 0.5% group, 40% in the 1% group, and 47% in the 2% group. Immune and biochemical parameters were assessed 14 days post-challenge. While total protein, triglycerides, and cholesterol levels did not differ significantly from the control group (<i>P</i> &gt; 0.05), immune parameters such as lysozyme and serum immunoglobulin levels increased significantly (<i>P</i> &lt; 0.05). Antioxidant parameters, including catalase (CAT) and superoxide dismutase (SOD), also showed significant enhancement. In conclusion, supplementation with a 2%&#xa0;<i>S. ilicifolium</i>&#xa0;extract is found to enhance growth, serum and mucosal immunity, digestive enzyme activity, and antioxidant parameters both before and after exposure to&#xa0;<i>S. iniae</i>.</p>

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The hydroalcoholic extract of Sargassum ilicifolium improves growth, immuno-antioxidant, digestive enzymes, and resistance to Streptococcus iniae in Asian seabass (Lates calcarifer)

  • 期刊论文

  • 发表日期：

    2025年9月4日

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  • Majid Khanzadeh,
  • Seyed Hossein Hoseinifar,
  • Aliakbar Hedayati,
  • Hamidreza Tabibi,
  • Majid Raahimi Golsefidi,
  • Hien Van Doan

摘要

Immunostimulants like seaweed can significantly enhance the immune response and disease prevention in aquatic animals. These substances boost fish resistance to infections by strengthening the nonspecific immune system, thereby improving overall health and pathogen combat capabilities. This study investigated the effects of the brown macroalga Sargassum ilicifolium extract on Asian seabass (Lates calcarifer), including growth, mucosal and serum immune responses, serum biochemical markers, bactericidal activity in serum and mucus, digestive enzyme activity, and resistance against Streptococcus iniae. A total of 360 Asian seabass with an average weight of 50.41 ± 1.08 g were divided into four treatment groups, each with three replicates. The fish were fed S. ilicifolium extract at concentrations of 0%, 0.5%, 1%, and 2% for eight weeks. Results showed that growth parameters, final weight, weight gain percentage, and specific growth rate increased significantly at 1% and 2% levels compared to the control group (P < 0.05). The food conversion ratio also decreased significantly with these concentrations. Immune parameters such as serum and mucus bactericidal activity, mucus lysozyme, and immunoglobulin levels were significantly enhanced at the 1% and 2% levels (P < 0.05). Furthermore, digestive enzymes like alpha-amylase (1% and 2%), trypsin (2%), and lipase (1% and 2%) showed significant increases after eight weeks of administration (P < 0.05). Following the feeding period, fish were challenged with S. iniae, revealing survival rates of 15% in the control group, 25% in the 0.5% group, 40% in the 1% group, and 47% in the 2% group. Immune and biochemical parameters were assessed 14 days post-challenge. While total protein, triglycerides, and cholesterol levels did not differ significantly from the control group (P > 0.05), immune parameters such as lysozyme and serum immunoglobulin levels increased significantly (P < 0.05). Antioxidant parameters, including catalase (CAT) and superoxide dismutase (SOD), also showed significant enhancement. In conclusion, supplementation with a 2% S. ilicifolium extract is found to enhance growth, serum and mucosal immunity, digestive enzyme activity, and antioxidant parameters both before and after exposure to S. iniae.