饥饿和再投喂对短须裂腹鱼幼鱼体组分、消化酶活性及RNA/DNA的影响

通过探究饥饿和再投喂过程中短须裂腹鱼幼鱼的鱼体组分、消化酶活性及RNA/DNA的变化规律,为其人工养殖提供科学依据。以短须裂腹鱼幼鱼为研究对象,用凯氏定氮法测定粗蛋白,索氏抽提法测定粗脂肪,恒温干燥失重法测定水分,马弗炉灼烧法测定粗灰分,电感耦合等离子体发射光谱法测定矿质元素,分光光度法测定消化酶活性和DNA、RNA含量。饥饿后,幼鱼粗脂肪含量在饥饿5天时降至最低值5.01%,粗蛋白含量在饥饿2天时降至最低值13.61%;水分和灰分上升,鱼体的Ca和P含量上升;鱼体K、Na、Mg及Fe含量均先上升再下降,且在饥饿9天时上升至最大值;幼鱼肝胰脏蛋白酶和脂肪酶活性均呈先升高后下降再升高趋势;淀粉酶活性下降,肌肉中的DNA含量上升,RNA含量下降,RNA/DNA下降。恢复投喂后,S15、S25组Fe含量低于对照组水平,各组淀粉酶活性均恢复至正常水平,S15和S25组脂肪酶活性显著低于对照组水平(P<0.05),S15、S25组RNA含量及RNA/DNA极显著下降(P<0.01)。在饥饿9天时,短须裂腹鱼幼鱼的生化指标未受显著影响,恢复投喂后的生化指标与对照组均无显著差异。建议在其养殖中饥饿时间不超过9天。

Effects on Fish Body Composition,Digestive Enzyme Activity and RNA/DNA of Schizothorax wangchiachii Juveniles: Starvation and Refeeding

The study was conducted to investigate the variation of fish body composition, digestive enzyme activity and RNA/DNA ratio of Schizothorax wangchiachii juveniles after starvation and refeeding, to provide a scientific basis for artificial culture. S. wangchiachii juveniles were used as materials. Crude protein, crude fat, moisture and crude ash of the fish body were measured by Kjeldahl method, Soxhlet extraction method, Thermostatic and weightless drying method and muffle furnace burning method, respectively. The mineral elements were measured using inductively coupled plasma atomic emission spectrometry, the digestive enzyme activity and the DNA/RNA ratio were measured by spectrophotometry. The results showed that the crude fat content of juveniles declined to the minimum of 5.01% after 5-day starvation. The crude protein content reduced to the minimum of 13.61% after 2-day starvation. The moisture and ash content, Ca and P content all increased after starvation. The contents of K, Na, Mg and Fe increased to the peak after 9-day starvation, and then decreased with starvation continued. The trypsin and lipase activity of liver-pancreas increased firstly, followed by a short decline, and then the activity finally increased. The amylase activities declined throughout the starvation time. The muscle’s DNA content increased, while RNA content and RNA/DNA ratio decreased. After refeeding, The Fe contents in group S15 and S25 were lower than those of the control group. The amylase activities of liver-pancreas recovered to normal level in all the groups. However, the liver-pancreas lipase activities of group S15 and S25 were significantly lower than that of the control group (P<0.05). The RNA content and RNA/DNA in muscle were extremely and significantly decreased in group S15 and S25 (P<0.01). The biochemical indexes of S. wangchiachii juveniles were not affected by 9-day starvation (P>0.05), and no significant difference with control was found after refeeding (P>0.05). The starvation time should not exceed 9 days.