|Abstract: ||海蝦對多元不飽和脂肪酸（Poly-unsaturated fatty acid）有營養的需求。然而，多元不飽和脂肪酸也是促氧化物，易引起自行氧化（autooxidation），所產生自由基（free radicals）可造成細胞內蛋白質、核酸及脂質過氧化，進而破壞細胞、組織及生物體正常功能。蝦紅素（Astaxanthin）為抗氧化物，增加蝦體蝦紅素的含量可以提升蝦抗氧化的能力，降低過氧化緊迫的傷害，因此本研究探討飼糧中此類促氧化物與抗氧化物共同對白蝦（Litopenaeus vannamei）的生物功能。研究中以魚油（Fish oil）、亞麻油酸（Linoleic acid）、硬脂酸（Stearic acid）為促氧化物，並以0、40、80、120mg kg-1濃度的蝦紅素為抗氧化物，每處理有三重複。將組合的飼糧餵予白蝦8週後，比較成長、活存、體蝦紅素含量、體脂肪酸組成、抗氧化狀態與低溶氧緊迫下呼吸參數的差異。結果顯示魚油組飼糧因含n-3多元不飽和脂肪酸，所餵飼的蝦不論成長與活存都較其他兩油脂好。蝦體中極性脂肪酸比例與脂肪酸組成受到飼糧油脂種類的影響。蝦體內多元不飽和脂肪酸的含量越高則氧化狀態越高，表現在高量的硫代巴比妥酸反應性物質（Thiobarbituric acid reactive substances）與過氧化物歧化酵素（Superoxide dismutase）上。飼糧油脂種類並不影響蝦體體蝦紅素的含量。白蝦的體內蝦紅素含量與呈色表現隨著飼糧中蝦紅素的濃度呈正比。體蝦紅素含量越高在養殖中的活存率越高，且對低溶氧緊迫的抵抗力越高。飼糧蝦紅素可保護蝦體內多元不飽和脂肪酸的完整性且提昇了蝦體內抗氧化能力，而表現在麩胱甘肽還原酶（Glutathion reductase）與麩胱胺肽過氧化酵素（Glutathione peroxidase）的升高及過氧化物歧化酵素、硫代巴比妥酸反應性物質的降低。體蝦紅素與體脂肪酸之間的無相關性，顯示飼糧中的蝦紅素與脂肪酸係各自獨立地影響其白蝦的生物功能。因此，添加魚油與高量的蝦紅素應是白蝦飼糧最適的組合。|
Marine shrimp have requirement for poly-unsaturated fatty acid (PUFA) However, as a prooxidant, PUFA is in favor of autooxidation and the production of free radicals, which can impair normal function of cell, tissue, and organism by the peroxidation of cellular proteins, nucleotides, and lipids. The increase of astaxanthin (AX), an antioxidant, in shrimp can enhance antioxidant capacity and reduce the damage from oxidative stress. Therefore, this study was aimed to find out the joint effects of aforementioned prooxidant and antioxidant in diet on the biological function of white shrimp Litopenaeus vannamei. Twelve diets supplemented with prooxidants as 3 types of fatty acid fish oil, linoleic acid, and stearic acid and antioxidant of 4 levels of AX: 0, 40, 80, and 120 mg kg-1, each had 3 replicates, were fed to the shrimp for 8 weeks. At the end, comparisons were made on growth, survival, body AX content, body fatty acid composition, antioxidant status, and respiratory parameters under low dissolved oxygen stress. Shrimp in fish oil group had better growth and survival than shrimp in the other two fatty acid groups since fish oil contained high level of n-3 PUFA. The ratio of neutral fatty acid to polar fatty acid in shrimp was affected by the type of dietary fatty acid. Shrimp having high PUFA content exhibited high oxidation status as shown in high values of thiobarbituric acid reactive substances (TBARS) and superoxide dismutase (SOD). Dietary lipid type did not affect body astaxanthin content in shrimp. Shrimp AX content and pigmentation increased with dietary AX concentration. The higher body AX content, the higher shrimp’s survival during rearing, and the higher resistance to low dissolved oxygen stress. AX could protect the integrity of PUFA in shrimp body and enhance shrimp’s antioxidant capacity, as shown in the increase of glutathione reductase and glutathione peroxidase and reduction of SOD and TBARS. No correlations between body AX content and fatty acids indicated that either perform its biological function independently. Therefore, supplementation of fish oil and high concentration of AX is considered best dietary combination for this shrimp.