摘要:
以鮻鱼(Liza haematocheila)为研究对象,采用半静态实验法探讨了摄食水平和氨氮联合作用对鮻鱼幼鱼摄食、食物转化率、生长、肠胃蛋白酶等方面的影响。结果表明:氨氮对鮻鱼幼鱼的摄食具有抑制作用,高浓度氨氮(3.32mg·L-1)对幼鱼摄食的抑制率达28.78%。鮻鱼幼鱼对食物的转化率(FCE)随氨氮浓度升高而减小,随着摄食水平的增加而增加,FCE最大值出现在饱食未添加氨氮组(BS5),为19.83%;最小值出现在低摄食水平的高浓度氨氮组(HS1),为-22.19%。鮻鱼幼鱼特定生长率(SGR)的增长水平受摄食水平和氨氮的影响与幼鱼的FCE变化一致。氨氮对实验幼鱼肠胃蛋白酶活性的影响因摄食水平而不同,本实验中,仅饱食条件下高浓度氨氮对幼鱼的肠胃蛋白酶有显著抑制效应,这可能与氨氮胁迫情况下幼鱼摄食量较小有关;氨氮浓度相同时,对照组和低氨氮浓度组鮻鱼幼鱼肠胃蛋白酶活性受摄食水平影响显著,而高氨氮浓度条件下,由于饱食组幼鱼肠胃蛋白酶活性受抑制,导致摄食水平对肠胃蛋白酶活性影响不显著。研究证实,摄食水平是影响鮻鱼生长及肠胃蛋白酶活性的主要因素,氨氮会抑制鮻鱼摄食,进而影响蛋白酶活性。
Abstract:
Static-renewal method was applied to study the effects of total ammonia (TAN) and ration level on food intake, food conversion efficiency (FCE), growth and pepsin activities of juvenile mullet Liza haematocheila. It was found that the ammonia exposure had a negative effect on the food intake of juvenile mullet, with an inhibition rate of 28.78% under high level ammonia (3.32mg L-1). The FCE of juvenile mullet decreased with the increase of ammonia concentration, while the ration level played a positive effect on the FCE of juvenile mullet. The highest value of FCE was found in group BS5, with a value of 19.83%, and the lowest in HS1, with its value-22.19%. The general trend of special growth rate (SGR) of juvenile mullet was similar with that of FCE. The effect of ammonia exposure on the pepsin activity of juvenile mullet was different from each ration level, only the pepsin activities of juvenile mullet from high level feeding group was depressed by the high concentration of ammonia, showing apossible relation with food intake. The pepsin activities of juvenile mullet under control and low-concentration groups were significantly impacted by ration level while under high concentration the influence was not significant. The food intake were the main factor to influence the growth and pepsin activity of mullet, and the high concentration ammonia may indirectly influence the pepsin activity by inhibiting the food intake of juvenile mullet.
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