Tejpal C S, Sumitha E B, Pal A K, Shivananda Murthy H, Sahu N P, Siddaiah G M
National Fisheries Development Board, Hyderabad, Andhra Pradesh 500 052, India.
Regional Shrimp Hatchery, Department of Fisheries, Kerala, India.
J Therm Biol. 2014 Apr;41:59-64. doi: 10.1016/j.jtherbio.2014.02.008. Epub 2014 Feb 12.
A 60 day feeding trial was conducted to study the effect of dietary l-tryptophan on thermal tolerance and oxygen consumption rate of freshwater fish, mrigala, Cirrhinus mrigala reared under ambient temperature at low and high stocking density. Four hundred eighty fingerlings were distributed into eight experimental groups. Four groups each of low density group (10 fishes/75L water) and higher density group (30 fishes/75L water) were fed a diet containing 0, 0.68, 1.36 or 2.72% l-tryptophan in the diet, thus forming eight experimental groups namely, Low density control (LC) (basal feed +0% l-tryptophan); LT1 (basal feed+0.68% l-tryptophan); LT2 (basal feed+1.36% l-tryptophan); LT3 (basal feed+2.72% l-tryptophan); high density control (HC) (basal feed+0% l-tryptophan); HT1 (basal feed+0.68% l-tryptophan); HT2 (basal feed+1.36% l-tryptophan); and HT3 (basal feed+2.72% l-tryptophan) were fed at 3% of the body weight. The test diets having crude protein 34.33±0.23 to 35.81±0.18% and lipid 423.49±1.76 to 425.85±0.31KCal/100g were prepared using purified ingredients. The possible role of dietary l-tryptophan on thermal tolerance and oxygen consumption rate was assessed in terms of critical thermal maxima (CTMax), critical thermal minima (CTMin), lethal thermal maxima (LTMax) and lethal thermal minima (LTMin). The CTMax, CTMin, LTMax and LTMin values were found to be significantly higher (p<0.05) in the treatment groups with CTMax 42.94±0.037 (LT2); LT Max 43.18±0.070 (LT2); CTMin 10.47±0.088 (LT2) and LTMin 9.42±0.062 (LT3), whereas the control group showed a lower tolerance level. The same trend was observed in the high density group (CTMax 42.09±0.066 (LT3); LTMax 43 23±0.067 (HT3); CTMin 10.98±0.040 (HT3) and LTMin 9.74±0.037 (HT3). However, gradual supplementation of dietary l-tryptophan in the diet significantly reduced the oxygen consumption rate in both the low density group (Y=-26.74x+222.4, r²=0.915) and the high density group (Y=-32.96x+296.5, r²=0.8923). Dietary supplementation of l-tryptophan at a level of 1.36% improved the thermal tolerance level and reduced the oxygen consumption rate in C. mrigala fingerlings.
进行了一项为期60天的饲养试验，以研究日粮中L-色氨酸对在环境温度下以低密度和高密度饲养的淡水鱼——印度鲮（Cirrhinus mrigala）的耐热性和耗氧率的影响。480尾鱼苗被分配到8个实验组。低密度组（10尾鱼/75升水）和高密度组（30尾鱼/75升水）各有4个组，分别投喂含0%、0.68%、1.36%或2.72% L-色氨酸的日粮，从而形成8个实验组，即低密度对照组（LC）（基础饲料+0% L-色氨酸）；LT1（基础饲料+0.68% L-色氨酸）；LT2（基础饲料+1.36% L-色氨酸）；LT3（基础饲料+2.72% L-色氨酸）；高密度对照组（HC）（基础饲料+0% L-色氨酸）；HT1（基础饲料+0.68% L-色氨酸）；HT2（基础饲料+1.36% L-色氨酸）；HT3（基础饲料+2.72% L-色氨酸），投喂量为鱼体重的3%。使用纯化成分制备粗蛋白含量为34.33±0.23%至35.81±0.18%、脂质含量为423.49±1.76至425.85千卡/100克的试验日粮。根据临界热最大值（CTMax）、临界热最小值（CTMin）、致死热最大值（LTMax）和致死热最小值（LTMin）评估日粮中L-色氨酸对耐热性和耗氧率的可能作用。发现处理组的CTMax、CTMin、LTMax和LTMin值显著更高（p<0.05），其中CTMax为42.94±0.037（LT2组）；LTMax为43.18±0.070（LT2组）；CTMin为10.47±0.088（LT2组）；LTMin为9.42±0.062（LT3组），而对照组的耐受性水平较低。在高密度组中也观察到相同趋势（CTMax为42.09±0.066（LT3组）；LTMax为43.23±0.067（HT3组）；CTMin为10.98±0.040（HT3组）；LTMin为9.74±0.037（HT3组））。然而，日粮中逐渐添加L-色氨酸显著降低了低密度组（Y=-26.74x+222.4，r²=0.915）和高密度组（Y=-32.96x+296.5，r²=0.8923）的耗氧率。日粮中添加1.36%的L-色氨酸提高了印度鲮鱼苗的耐热性水平并降低了耗氧率。
