饥饿与再投喂对方斑东风螺生长、基本营养成分及RNA/DNA比值的影响

在(25.8±1.7)℃条件下,测定了方斑东风螺(5.25±0.53)g在不同时间(7、15、25和40d)饥饿处理后再投饵30d过程中的生长参数、基本营养成分及组织RNA/DNA比值的变化。饥饿状态下,螺体水分含量逐渐上升,第15天时显著高于对照组;脂肪与糖原含量均下降,并分别于饥饿15d、25d时显著低于对照组(P<0.05);而蛋白质含量在不同处理组间无显著性差异(P>0.05);足肌与肝胰脏中RNA/DNA比值均随饥饿时间延长而逐渐降低。恢复生长后,除饥饿40d组含水量显著高于对照组外(P<0.05),该组其余营养成分及其它各组相应指标均恢复至或接近对照组;RNA/DNA比值除在饥饿40d组肝胰脏中仍较低外均接近或显著高于对照组。各组幼螺摄食率(FR)均高于或显著高于对照组(P<0.05),体重增量、食物转化率(FCE)在前3处理组及特殊生长率(SGR)在饥饿7d与25d组均与对照组间无显著差异(P>0.05),而饥饿15d组的SGR显著高于对照组(P<0.05);饥饿40d组尽管FR显著提高,但体重增量、FCE及SGR均显著低于对照组(P<0.05)。结果表明,方斑东风螺幼螺饥饿时主要消耗脂肪与糖原...

Effects of starvation and recovery on growth, proximate composition and RNA/DNA ratio in juvenile spotted ivory shell(Babylonia areolata)

To investigate the compensatory growth responses of the scavenging gastropod Babylonia areolata,a refeeding after starvation study was performed at (25.8 ± 1.7) ℃. Juvenile spotted ivory shells weighing a mean of 5.25 g were starved for 7 (S7), 15 (S15), 25 (S25), and 40 (S40) days, respectively, and then fed to satiation once a day during the 30 days refed period. The four corresponding control groups were fed to satiation during the experiment. Three tanks each containing 30 snails made up a group. The results indicated that the water contents of the whole soft body increased gradually during starvation, and was significantly higher than that of the control when the snails were fasted for 15 days (P <0.05). The lipid and glycogen contents were significantly lower than those of the controls when food were prohibited for 15 days and 25 days respectively (P <0.05), while there were no significant differences in protein contents (P > 0.05). The ratios of RNA/DNA in foot muscle and hepatopancreas of the snails both decreased gradually during the fasting period. After 30 days recovery growth, except for the water content in the S40 group,which was significantly higher than that of the control (P < 0.05), there were no significant differences in other biochemical composition between refed and control groups(P >0.05). The ratios of RNA/DNA were near or markedly higher than that of the control except in hepatopancreas of the S40 group which was lower than that of the control (P <0.05). The feeding rate (FR) during refed period was higher (for S7, S15)or significantly higher (for S25, S40) than that of the controls which were fed throughout the experiment,there were no significant differences in food conversion efficiency (FCE) and increments of body weight between the S7, S15, S25 groups and their controls respectively, as well as no significant differences were found between the S7, S25 groups and the controls respectively as to specific growth rate (SGR) (P >0.05), while the SGR was markedly higher than that of the control in the S15 group (P <0.05). Whereas there were significant decreases in the FCE, SGR and increment of body weight for the S40 group, although the FR of this group was greatly increased compared to the control (P < 0.05). In conclusion, the snails could utilize lipid and glycogen first as energy resource when being deprived of food, and there is complete compensatory growth in snails as the starvation period was no more than 25 days. The results of the present study indicate that prolonging the feeding intervals properly can facilitate the culture manipulation and spare food under the premise of not affecting the growth rate of the snails, and the RNA/DNA ratios in the two tissues are a valid indicator of nutritional condition in spotted babylon juveniles.