养殖密度对斑节对虾生长、肝胰腺抗氧化、免疫性能及其相关基因表达和肠道健康的影响

Effects of stocking density on growth, hepatopancreatic antioxidant, immune performance, related gene expression, and intestinal health of Penaeus monodon

  • 摘要:
    目的 探究斑节对虾健康养殖的适宜放养密度。
    方法 随机选择初始体重(2.55±0.19)g、体长(6.71±0.20)cm的健康斑节对虾,设225、300、375、450、525和600尾/m3共6个不同密度梯度,分别标记为D225、D300、D375、D450、D525和D600,进行为期42 d的养殖实验。
    结果 随着养殖密度的增加,斑节对虾的存活率逐渐下降,而增重率、特定生长率和肥满度则是先升后降,饲料系数为先降后升。肝胰腺抗氧化和免疫性能方面,D375表现最佳,其SOD、AKP和ACP活性显著高于其他组,MDA含量及Prxp53、MyD88和LZM的表达量显著低于其他组。肠道菌群多样性随养殖密度的增加呈现先升后降的趋势,其中D225和D600的Alpha多样性指数显著低于其他组。肠道菌群物种分布情况显示,D450的有益菌(如厚壁菌门和乳酸杆菌属)相对丰度最高,有害菌(如变形菌门)相对丰度最低。肠道组织形态观察显示,D375和D450的斑节对虾肠道结构较完整,肠绒毛密集、排列整齐且高度明显高于其他组,而其他组的肠道有部分上皮细胞脱落,甚至绒毛缺失。
    结论 过低或过高的养殖密度均不利于斑节对虾的生长和生理功能调节,375~450尾/m3的养殖密度最有利于促进斑节对虾的生长,并且提高其肝胰腺的抗氧化能力、非特异性免疫力及优化肠道微生物群落结构。本研究为斑节对虾养殖密度的优化提供了实验依据,以期提高养殖效益,促进斑节对虾养殖的绿色健康发展。

     

    Abstract: The study was carried out to investigate the optimal stocking density of Penaeus monodon. Healthy shrimps initial body weight (2.55±0.19) g, body length (6.71±0.20) cm were randomly distributed into six different stocking densities (225, 300, 375, 450, 525, and 600 ind/m3), labeled as D225, D300, D375, D450, D525, and D600, respectively. Culturing for 42 days. The results showed that the survival rate (SR) gradually decreased with increasing stocking density. Furthermore, the weight gain rate (WGR), specific growth rate (SGR), and condition factor (CF) were increased first and then decreased, while the feed conversion ratio (FCR) was conversely. Antioxidant and immune properties of hepatopancreatic indicated that D375 showed the best antioxidant and immune performance, whose activities of SOD, AKP, and ACP were significantly higher than that of the other groups (P<0.05), and the MDA content and expression of Prx, p53, MyD88, and LZM were significantly lower than that of the other groups (P<0.05). Regarding intestinal health, the Alpha diversity index of intestinal microbiota showed a trend to increase first and then decrease with the increasing stocking density. The Alpha diversity of D225 and D600 was significantly lower than that of the other groups (P<0.05). As for species distribution of intestinal microbiota, D450 showed the highest relative abundance of beneficial bacteria (e.g., Firmicutes and Ligilactobacillus) and the lowest one of harmful bacteria (e.g., Proteobacteria). By observing the intestinal structure and morphology, it was found that the intestinal structure of D375 and D450 was more complete, the villi arranged densely and neatly, and the villi height was higher than that of the other groups. In contrast, the other groups exhibited partial epithelial cell sloughing and villus loss. In summary, the study indicates that excessively high or low stocking density was not conducive to shrimp growth and physiological function regulation. The stocking density of 375-450 ind/m3 promoted growth, improved hepatopancreas antioxidant capacity and non-specific immunity and optimized the intestinal microbial community structure of the shrimp. This study provided an experimental basis for the optimum culturing density of P. monodon, which could help to improve the culture efficiency and promote the development of sustainable and healthy shrimp aquaculture.

     

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