饲料脂肪含量与奥尼罗非鱼幼鱼肝脏形态结构特征的相关性

研究了投喂不同脂肪含量饲料时奥尼罗非鱼幼鱼（Oreochromis niloticus×O．aureus）肝脏形态学与组织学的变化规律，旨在阐明饲料脂肪对奥尼罗非鱼幼鱼脂肪肝发生的影响。饲料脂肪水平设置为0％、2％、4％、6％和8％等5个梯度组。随着饲料脂肪水平逐渐升高，奥尼罗非鱼幼鱼的增重率与肥满度均先上升后下降，1～5组肥满度分别为1．63±0．14、1．78±0．21、1．92±0．18、1．80±0．21和1．74±0．24。脂肪水平对奥尼罗非鱼肝脏形态学有明显影响，4～5组病鱼的肝胰脏肿大，呈油腻状，颜色发黄，柔软粉糊，有的出现白色坏死病灶，部分胆囊肿大且颜色变深，肠系膜均有过量的白色脂肪沉积。脂肪水平对奥尼罗非鱼肝脏组织学亦有明显影响，1～5组试验鱼的肝细胞直径随之增大，低脂肪水平的1～3组与高脂肪水平的4～5组具有显著差异，平均值分别为8．9和17．9μm，高脂肪水平的4～5组呈现肝细胞核偏位、胞浆内脂肪滴较多、细胞透明空泡化等症状。研究认为奥尼罗非鱼幼鱼饲料中脂肪添加量超过4％时对其肝脏形态学与组织学有一定影响。

Correlation between lipid levels of feed and liver morphology characters of juvenile tilapia (Oreochromis niloticus x O. aureus)

The correlation between diet lipid levels and liver morphology and histology of juvenile tilapia （ Oreochromis niloticus × 0. aureus） were studied. The juvenile tilapia were fed five diets with graded lipid levels of 0%, 2%, 4%, 6%, 8% , respectively, for 70 days. The results showed that weight gain rate （WGR） and condition factor （CF） increased first and decreased later with the growing lipid content level. The feed conversion ratio （FCR） decreased first and increased later contrarily. The color and volume of liver and gallbladder of tested fish were different for different lipid content diets. Liver cells diameter increased continuously with the growing lipid content level. Liver cells diameter of group 4 and 5 were significantly larger than that of groups 1, 2 and 3. The symptom of fatty liver disease was appeared obviously in group 4 and 5. Liver cells shifted normal location. Fatty roundels increased in liver cells. And liver cells were translucent and like vacuole. Juvenile tilapia formed fatty liver disease easily if diet lipid content exceeds 6%. It suggested that the supplement of over 4% lipid in diets of juvenile tilapia would be harmful for fish liver.