Effects of Stevia Extract on Growth, Non-specific Immune Response and Disease Resistance of Grass Prawn, Penaeus monodon (Fabricius), Juveniles

為研究甜菊萃取液對草蝦Grass Prawn, Penaeus monodon (Fabricius)幼蝦的生長、非特異性免疫反應及抗病性的影響，針對草蝦之幼蝦（均重0.76克）和半成年蝦（均重14.7克）分別進行兩項實驗。30尾幼蝦及15尾半成年蝦分別養於200L玻璃纖維養殖槽內各4個月和1個月。實驗組以加有不同濃度(1, 2, 4, 8%)的甜菊萃取液的飼料餵養。對照組則以未加添加劑的商業用飼料飼養。幼蝦組每隔15天（自第45天）記錄體重。非特異性免疫參數（總血球數，酚氧化，呼吸爆，超氧化物歧化酶活性）在試驗結束時加以收集分析。半成年蝦則以細菌性病原Vibrio harveyi進行免疫感染試驗。結果顯示，添加甜菊萃取液的飼料對於草蝦的生長無顯著作用。但添加4%和8%的甜菊萃取液飼養的蝦總血球數明顯高於對照組及添加1%和2%甜菊萃取液飼養組。血細胞呼吸釋放活性的觀測也得到相似的結果。酚氧化酶活性在以2%-8%甜菊萃取液添加組觀察到明顯升高。而1%甜菊萃取液添加組則未觀察到與對照組之間有明顯區別。超氧化物歧化酶活性在最高濃度甜菊萃取液(8%)添加組未觀察到與對照組有明顯區別。在免疫感染試驗中以8%甜菊萃取液飼養組觀察到能完全保護（零死亡率之效果），而以4%甜菊萃取液飼養組死亡率為30%，而在對照組中觀察到最高死亡率(60%)。這一結果顯示甜菊萃取液以4%以上的濃度添加飼料中，可用作草蝦的免疫刺激劑。

關鍵字

甜菊萃取液；草蝦；非特異性免疫反應；抗病性

並列摘要

Two separate experiments were undertaken on grass prawn juveniles (mean body weight: 0.76 g) and sub-adults (mean body weight: 14.7 g) to study the effects of stevia exract on growth, non-specific immune response and disease resistance. Thirty (30) juveniles and 15 sub-adults were reared in 200-liter tanks for four months and one month, respectively. They were fed with stevia-supplemented feeds at different concentrations (1, 2, 4 and 8%). Control prawns were fed with non-supplemented commercial pellet. For juveniles, growth (body weight) was monitored every 15 days (starting at 45 days of culture). Non-specific immune parameters (total haemocyte count and phenoloxidase, respiratory burst and superoxide dismutase activities of haemocytes) were analyzed at the termination of the experiment. The sub-adults, on the other hand, were used for challenge experiment using the bacterial pathogen Vibrio harveyi. Results show that there was no significant effect on growth among prawns fed with stevia-supplemented feeds and that of the control. Total haemocyte counts of prawns fed with 4 and 8% stevia were significantly higher than the control and those fed with 1 and 2% stevia. Similar results were obtained for respiratory burst activity of haemocytes. For phenoloxidase activity, prawns fed with 2-8% stevia showed significantly higher activities, while those fed with 1% stevia did not differ from the control. Superoxide dismutase activity of haemocytes was not significantly affected by stevia except at the highest concentration of 8%. For the challenge test, complete protection (0% mortality) was observed on prawns fed 8% stevia while 30% mortality was observed on prawns fed 4% stevia. Highest mortality was observed on prawns fed with control diet (60% mortality). Results of this study show that stevia extract can be used as immunostimulant for grass prawn, which can be given through feed incorporation at concentrations of at least 4% or higher.

並列關鍵字

Stevia extract ； Penaeus monodon ； Non-specific immune response ； Disease resistance

國際替代計量

Effects of Stevia Extract on Growth, Non-specific Immune Response and Disease Resistance of Grass Prawn, Penaeus monodon (Fabricius), Juveniles

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