牛至油对慢性氨氮胁迫下幼鲤组织结构的影响

Effect of Oregano Oil on the Histology of Juvenile Common Carps Stressed by Ammonia Nitrogen

探讨牛至油对慢性氨氮胁迫下幼鲤各器官组织结构的保护作用,为集约化水产养殖提供参考依据。挑选450尾初始体重为(17.02±0.40)g的幼鲤,随机分为6组:L、L0、L300、L600、L900、L1200(L为对照组,养于正常水体中并饲喂基础饲料;其余5组为试验组,养于<4.87±0.21>mg/L氨氮水体中并分别饲喂添加0、300、600、900、1 200 mg/kg牛至油的试验饲料),每组设3个重复,每个重复25尾鱼,养殖试验为期56 d。结果表明,添加量为900 mg/kg时,牛至油对鳃、肝、肾组织发挥的缓解作用最大;当牛至油添加量达到1 200 mg/kg时,其缓解氨氮胁迫的作用降低。日粮中牛至油添加量为300、600、900 mg/kg可以显著增加肠绒毛高度;当牛至油添加量达到1 200 mg/kg时,牛至油对于肠绒毛的促生长作用减弱。在试验条件下,日粮中添加900 mg/kg的牛至油能够最大程度地缓解由氨氮胁迫造成的幼鲤鳃、肝和肾组织的损伤,并且对于幼鲤肠绒毛的生长具有促进作用。

Ammonia nitrogen is a primary environmental stressor for the growth and health of aquatic life. Non-ionic ammonia, one of the primary forms of ammonia nitrogen in waters, is toxic to fish and acts by damaging important organs, such as the gills, kidneys, liver and intestine, which results in declining disease resistance, growth rate and survival rate. Thus, to improve the growth performance and survival rates, it is crucial to promote healing of the histological lesions caused by ammonia nitrogen. In this study, a 56-day feeding trial was conducted to investigate the effects of dietary oregano oil on the gills, liver, kidneys, and intestine of juvenile common carps under chronic ammonia stress. Our aim was to provide evidence for the beneficial effects of adding dietary oregano oil in intensive aquaculture. A total of 450juvenile common carps with initial body weight of(17.02±0.40) g were selected and randomly assigned to18 tanks divided into six groups with three replicates per group. The control group(L) was exposed to normal water and fed a basic diet, and the five experimental groups(L0, L300, L600, L900, L1200) were all exposed to water with ammonia nitrogen of(4.87±0.21) mg/L and fed diets containing 0, 300, 600,900, 1 200 mg/kg of oregano oil. Under the chronic stress of ammonia nitrogen, the final weight, weight gain rate and specific growth rate of the L0 group were significantly lower than those of the control group L(P<0.05). With increased oregano oil in diet, the three growth parameters all increased initially and then decreased, peaking in the L600 group. There were no significant differences in the growth parameters among the L300, L600, L900 groups(P>0.05), but all were significantly higher than those for the L0group(P<0.05), and the weight gain of the L600 group was significantly higher than that of the L1200group(P<0.05). Supplementing the diet with oregano oil effectively alleviated the damage of chronic ammonia nitrogen stress to the gill, liver, kidney and intestine histology of juvenile common carps, with the best alleviation found in L900 group and the effect was less at 1 200mg/kg. The dietary oregano oil in the L300, L600 and L900 groups significantly increased the height of intestinal villi and promoted intestinal tract growth and development. At a level of 1 200mg/kg, the growth-promoting effect of oregano oil on intestinal villi weakened. In conclusion, the optimal supplement of dietary oregano oil was 900 mg/kg for alleviating damage to the gills, liver, kidneys and intestine caused by ammonia nitrogen, and for promoting the growth of intestinal villi in juvenile common carp.