|Abstract: ||南美白對蝦 (Litopeneaus vannamei) 是最常見的商業水生物種之一，現今常用的集約式養殖系統導致了其疾病易發情形，為了克服這些問題，通過天然來源的免疫刺激物來增強免疫系統被認為是一種有效的方法。其中，由藻類萃取出的多種生物活性物質已被證實能夠促進其免疫免應，並具有很大的發展潛力。本研究採集銅藻 (Sargassum horneri) 以取得銅藻熱水萃取物 (SHE)，探討其對白蝦生長的影響，包括：生長率、增重率、存活率與飼料轉化率。對白蝦免疫反應的影響，檢測包括：總血球細胞計數、酚氧化酶活性、活性氧產量與吞噬作用速率。實驗中並分析白蝦免疫相關基因表現的影響，以開發銅藻作為蝦類飼料中之免疫調節劑。 在體外實驗中，結果顯示對白蝦血球細胞使用0.05 - 2% SHE可增強其免疫能力，以1% SHE刺激後，蝦血細胞的酚氧化酶活性和活性氧產量為最高，分別達到0.263 ± 0.031和830 ± 46.15。在投餵試驗中，以投餵添加0.5% SHE飼料之白蝦增重率為最佳，達157.85 ± 7.1 %；白蝦存活率以投餵含有0.25與0.5% SHE之飼料為最高，達93.35 ± 6.65與84.47 ± 2.23%。在免疫反應實驗中，以投餵添加1% SHE飼料之總血球細胞數、酚氧化酶活性、活性氧產量與吞噬作用速率為最高，分別達230.15 ± 50.2×105 cells ml-1、0.198 ± 0.03、2549.98 ± 65.90與14.1 ± 2.42 %，並皆隨著飼料中SHE濃度和投餵時間而增加，但在連續投餵28天後有緩慢下降的情形。 在基因表現實驗中，以投餵添加0.5％ SHE飼料之免疫相關基因表現為最高，包含lipopolysaccharide、β-1,3-glucan binding protein (LGBP)、peroxinectin (PE)、prophenoloxidase I (ProPO I)、prophenoloxidase II (ProPO II)、α2型巨球蛋白(A2Ms )、抗LPS因子(Anti-LPS factor , ALF)、Crustin (Cru)、溶菌酶 (Lyz)、Penaedin2 (CP)、過氧化物酶歧化酶 (SOD)、穀胱甘肽過氧化酶 (GPx) 酶與凝血蛋白等 (CP)，共計12種基因。總體而言，添加0.5 - 1%的銅藻熱水萃取物即可達到提升免疫與生長之效果，銅藻熱水萃取物SHE可作為白蝦免疫調節劑之來源，以增強調節蝦類免疫力和白蝦成長相關因子。|
The white shrimp Litopeneaus vannamei is one of the most common commercial aquatic species. Unfortunately, intensive aquaculture systems in an attempt to meet the demands have led to challenging disease outbreaks. To overcome these issues, a natural source of strengthening the immune system through immunoregulator has been considered as an effective approach. Among them, algae have been proven to have significant effects in promoting immunity and has great potential for development because of its immuno-regulating properties. To solve the environment problem and enhance shrimp industry, we collected Sargassum horneri, which was floated to the coast of Waimusan, Keelung city, to explore S. horneri hot-water extract (SHE) on the growth performance including specific growth rate (SGR), weight gain (WG), survival rate (SUR) and Feed Conversion Ratio (FCR); the immune responses including total haemocyte count (THC), phenoloxidase activity (PO activity), reactive oxygen species (ROS) production, and phagocytic rate; the expression of immune-related genes. In the in vitro experiment, shrimp received SHE 0.05% - 2% has shown increased the immune parameters. PO activity and ROS production of shrimp hemocytes incubated in SHE at 1% were significantly enhanced and reached the value of 0.263 ± 0.031 and 870.33 ± 46.15, respectively. In in vivo experiments, WG in shrimp fed diets at 0.5% SHE obtained a value of 157.85 ± 7.1% which were significantly higher than other groups. Similarly, in shrimp fed diets containing SHE with 0.25 and 0.5% had the best SUR with the value of 93.35 ± 6.65 and 84.47 ± 2.23%. In immune response experiments, the highest value was found at 1% SHE supplementation in THC, PO, ROS, Phagocytic rate with values of 230.15 ± 50.2 x 105 ml-1, 0.198 ± 0.03, 2549.98 ± 65.90, and 14.1 ± 2.42%. These parameters were directly increased with dosage and feeding time. However, they slowly decreased after 28 days of feeding. In gene expression experiment, white shrimp L. vannamei fed diets containing 0.5% of SHE in 28 days showed significantly up-regulated 12 immune-related genes including lipopolysaccharide and β-1,3-glucan binding protein (LGBP), peroxinectin (PE), prophenoloxidase I (ProPO I), prophenoloxidase II (ProPO II), α2macroglobulin (A2M), anti-lipopolysaccharide factor (ALF), crustin (Cru), lysozyme (Lyz), penaiedin2 (Pen2), superoxidase dismutase (SOD), glutathione peroxidase (GPx) and clotting protein (CP). In conclusion, to enhance immune and growth performance, SHE at 0.5-1% supplementation is sufficient to achieve significant effects, can be used as a natural source of immunoregulators in shrimp.