【作者】 王立波；

【导师】 刘伟；

【作者基本信息】 东北农业大学 ， 动物遗传育种与繁殖， 2007， 硕士

【摘要】 怀头鲇是我国新开发的一种养殖鱼类，由于其生长速度快，肉质鲜美而受到养殖业者和消费者的普遍欢迎。对于新开发的养殖对象，全面了解其消化生理特征，尤其是了解幼鱼消化酶的种类性质、时间分布及活性变化，对全面了解幼鱼的食性转化、营养生理特点以及研制开口饲料具有重要的意义。本论文研究了pH值、温度、底物浓度等理化因素对怀头鲇幼鱼体内主要消化酶(蛋白酶、脂肪酶、淀粉酶)活性的影响；同时，研究了怀头鲇仔、稚鱼期消化酶及碱性磷酸酶活性的分布和变化趋势，探讨了摄食前后怀头鲇幼鱼消化酶活性的变化等。结果如下：1．怀头鲇幼鱼胃蛋白酶作用的适宜pH为2.6左右：肠蛋白酶作用的适宜pH为9.8～10.3；胃淀粉酶作用的适宜pH为6.0，肠淀粉酶作用的适宜pH为7.0～7.4。胃蛋白酶作用的最适温度为35℃左右，肠蛋白酶作用的最宜温度为40～45℃；胃淀粉酶作用的最宜温度为45℃，肠淀粉酶作用适宜温度为40～45℃。胃和肠蛋白酶作用适宜底物浓度都为0.5％干酪素；胃淀粉酶作用适宜底物浓度为0.5％可溶性淀粉。2．在怀头鲇早期发育过程中，消化酶活性随日龄增加依酶类不同呈现不同变化趋势，并表现一定波动性。自孵化后2d龄起，仔鱼的各种消化酶活性开始上升，其酸性蛋白酶活性呈由弱渐强缓慢上升趋势，碱性蛋白酶活性随日龄增加上升较快，3～10d龄期间，仔鱼的碱性蛋白酶活性均明显高于酸性蛋白酶，在5d龄时即达到较高值，而酸性蛋白酶在10d龄达到峰值。脂肪酶活力的波动相对平稳，酶活力在4d龄最高，而淀粉酶活性在仔鱼摄食初期活性很高，之后随日龄增加明显下降。在4d龄和8d龄时，碱性蛋白酶和淀粉酶活力均有不同程度下降，而脂肪酶均在此期间有所升高，显示出鱼类早期发育阶段中消化酶的变化与消化生理特点。消化酶的变化与仔鱼营养和食性转化密切相关，推测怀头鲇约在8d龄时完成由内源至外源营养的机能转换。碱性磷酸酶与蛋白酶的变化趋势相近，随着怀头鲇的生长发育活性一直缓慢上升。3．摄食后幼鱼胃蛋白酶活性下降，随后开始快速上升至摄食后3h酶活性达到最高值，与摄食前相比差异显著(P＜0.05)；而肠蛋白酶活性一直保持上升趋势，摄食后3h酶活性达到最高值。胃淀粉酶活性在摄食1h后明显的降低(P＜0.05)，但很快又迅速上升，到摄食后3 h达到最高值；肠淀粉酶在摄食后表现为先降低后增加的趋势，摄食后5 h达到最高值。同时发现，摄食前后胃中脂肪酶活性变化较为剧烈，摄食后3 h达到最高峰，而肠道中脂肪酶活性的变化较为缓慢，说明摄食对胃中脂肪酶活性影响较大。更多还原

【Abstract】 Now the northern Sheatfish (Silurus soldatovi) culture becomes a new industry in oureconomy.In order to promote its culture in our country, it is very necessary to do some work on itsbasic research. In this study, the main digestive enzymes in northern Sheatfish were fully discussed.The physico-chemical characters (pH value, temperature and substrate-concentration)ofdigestive enzymes and the effect of feeding on the activity of protease、amylase and lipase in themain digestive organs of northern sheatfish were studied in this paper, simultaneity, the activities ofsome digestive enzymes and alkaline phosphatase were investigated during the larval and juveniledevelopment of northern sheatfish.The results are as follows.1. The optimum pH of protease in stomach is 2.6,protease in intestine canal is 9.8～10.3.Theoptimum pH of amylase in stomach is 6.0,amylase in intestine canal is 7.0～7.4.The optimumtemperature of protease in stomach is about 35℃, protease in intestine canal is 40～45℃, amylase instomach is 45℃, amylase in intestine canal is 40～45℃. The optimum substrate-concentration ofprotease in stomach and intestine canal are 0.5％casein,amylase in stomach is 0.5％dissolvablestarch.2. During the first developmental life of northern sheatfish (1～10 days old), the alkalineprotease, lipase and amylase activities changed very markledly,the acid protease activities appearedthe rising current gradually.The alkaline protease activities appeared the rising current in dailyfluctuating period. The result indicated that the larva of northern sheatfish had the effectiveactivities of the acid protease about 2 days old of hatching during the first developmental days.Thealkaline protease activities were better than the acid protease activities at the process of the entireforepart development, which achieved the high value in the 5 days old, subsequently, but the acidprotease achieved the high value in the 10 days old. The lipase change was steady in the process ofthe forepart development, the first high value appeared in the 4 days old. The amylase activity waseffective in the early phase,which decreased along the increase of days old.. The alkaline proteaseand amylase activities decreased in the 4th and 8th days old,but the lipase activities increased.At thedevelopment of northern sheatfish ,the digestive enzymes changed markedly in the alimentarytract,it showed that the digestive enginery was improving during the larval and juveniledevelopment of northern sheatfish.These patterns indicated a maturation of enterocytes and theacquisition of an adult mode of digestion within the first month of live.3. The activity of protease in stomach decreased after feeding,then increased and kept at a highlevel after 3h of feeding (P＜0.05). But the activity of protease in intestinal canal increased all alongand kept at a higher level after 4h of feeding.The effect of feeding on the activity of amylase indicated that the amylase in stomach decreased after 1h of feeding (P＜0.05), then increased andkept at a higher level after 3h of feeding, which was 15.87±2.02 U/mg protein.Trend of amylaseactivities in stomach change appeared from low to high.The activity of amylase in intestinal canalkept at a higher level after 5h of feeding. At the same time,the results showed the activity of lipasein stomach changed quite acutely, which kept at a higher level after 3h of feeding, but the activityof lipase in intestinal canal changed slack, The feeding effect the activity of lipase in stomach wasmore distinct than the activity of lipase in intestinal canal.更多还原