臺灣博碩士論文加值系統

　　水產養殖使用人工飼料的目的，主要是提高能量來源與促進魚體成長。已知市售水產飼料中之脂質品質差異甚大，且抗氧化劑的添加以二丁基羥基甲苯（Dibutylated hydroxytoluene, BHT）為主。因此為了解不同氧化程度的黃豆油與添加高量BHT的飼料對養殖魚類之影響，乃以高經劑魚種一鰻魚為實驗對象，分別投喂控制組過氧化物價（Peroxide value, POV）為17.2 meq/kg oil、不同氧化程度（POV 28.2、55.4及97.4 meq/kg oil），以及不同氧化程度且添加BHT (POV 27.7、52.0及94.1 meq/kg oil + 0.02% BHT）的飼料12週。結果不論是在只添加氧化油的飼料組，或是合併0.02% BHT之氧化油的飼料組，其魚體在成長的表現上均較控制組差，且肝體比值（Hepatosomatic index, HSI）亦高於控制組。另外，添加氧化油的飼料組以及合併0.02% BHT之氧化油飼料組，鰻魚肝臟中總Glutathione (Total GSH）與還原態Glutathione (Reduced GSH) 的含量，均隨著實驗時間的增加而含量有明顯下降的趨勢，但是這些生化上的改變在鰻魚重新接受控制組飼料兩週後，即有改善的情形出現。肌肉中Thiobarbituric acid reactive substances (TBARS)的濃度，則隨著飼料中POV值的增加而增加，其中投與含有BHT的飼料組者，雖比飼料中僅有氧化油組者低，但仍與控制組者有意義的增加。再經由組織切片可進一步觀察到，隨著飼料中氧化程度的提高，鰻魚肝細胞出現肥大（Hypertrophy）、排列不規則甚至細胞壞死(Cell necrosis)等病理現象之程度也相對增加、經過2週的回復實驗發現，飼料的氧化程度小於60 meq/kg oil以及合併0.02% BHT添加等組之細胞大小逐漸復原，細胞再生(Regeneration)，但POV大於90 meq/kg oil組鰻魚，其肝細胞恢復的情形較差。
　　又由於國內鰻魚養殖場多分佈於中南部沿海地帶，根據環保署所委託的研究調查指出，臺灣西南海域在廠夏季時水瘟較高，為知在不同溫度下氧化飼料對鰻魚之影響，乃在水溫變化的壓力下，給與鰻魚油脂品質較差的飼料(63.0 meq/kg oil) 8週。結果顯示，在水溫32℃下飼養之鰻魚，飼料中不含維生素C和E，以及飼料中只含維生素C或E之飼料組，在體重的增加、總GSH和還原態GSH含量均比飼料中含有維生素C和E組者有顯著差異，且明顯比同樣飼料條件但殖水溫在26℃者不佳。另外在Aspartate transaminase (AST)和Alanine transaminase (ALT)的活動性方面，在水溫26℃下飼之鰻魚，除了飼料中不含維生素C和E組活性較高外，蓁各組間並沒有顯著差異。在水溫32℃下飼養這鰻魚，不論是飼料內不含維生素C和E，或僅含維生素C和E組，其AST和ALT之酵素活性遠高於飼料中含有維生素C和E組者，肌肉中TBARS的含量也有相同的情況。顯示鰻魚在高溫及不當飼料的養殖環境下，對魚體本身會造成不良的影響。

　　The effects of oxidized oil and BHT on the Japanese eel (Anguilla japonica) were determined. Japanese eel were treated with POV 27.7 to 97.4 meq/kg oil and 0.02% BHT in their diet for 12 weeks. The growth rate and glutathione content in liver were found to significantly decrease when Japanese eel were fed a diet with supplements of oxidized oil (POV> 50 meq/kg oil) and 0.02% BHT. The hepatosomatic index (HSI) and the level of thiobarbituric acid-reactive substances (TBARS) were found to significantly increase when Japanese eel were fed a diet with supplements of oxidized oil and 0.02% BHT. The pathological symptoms in hepatocytes induced by oxidized oil and BHT were observed under microscope. The lesions indicated that the hepatocytes had hypertrophy, arrangement irregular and necrosis, but these symptoms were alleviated when the fish were switched to the without containing oxidized oil and BHT diet. The Japanese eel were cultured at two temperature (26 amd 32℃) and fed various diets including: moderately (POV 63.0 meq/kgoil) oxidized oil with or without supplement of ascorbic acid and/or DLatocopherol for 8 weeks. The growth rate and glutathione content in liver were found to be significantly higher in the fish fed the diet with supplements of ascorbic acid and DLatocopherol than in fish fed diets with supplement of ascorbic acid or DLatocopherol, and without supplements of ascorbic acid and DL-α-tocopherol.
　　It was also found that the growth rate and glutathione content in liver were lower in fish cultured at 32℃ than in fish cultured at 26℃. The activities of aspartate transaminase (AST) and alanine transaminase (ALT) in plasma and the level of thiobarbituric acid-reactive substances (TBARS) in muscle were lower in the fish fed the diet with supplements of ascorbic acid and DLatocopherol than in other groups. It was also found that the activities of AST and ALT in plasma and the level of TBARS in muscle were higher in fish cultured at 32℃ than in fish cultured at 26℃.