驯食策略对鳡幼鱼存活、生长、肠道组织学与消化酶及肝脏转录组的影响

WEANING STRATEGY ON SURVIVAL,GROWTH,INTESTINAL HISTOLOGY,ENZYME ACTIVITY,AND LIVER TRANSCRIPTOME OF JUVENILE YELLOWCHEEK CARP ELOPICHTHYS BAMBUSA

为探究鳡(Elopichthys bambusa)适宜驯食时机及驯食对其生长和肠道健康的影响,研究设置了分别从15、22和29 dph开始驯食鳡幼鱼的3个驯食组(W15、W22和W29),探究不同起始时间驯食对鳡幼鱼生长、存活、肠道发育及肝脏转录组的影响。结果显示,W22和W29组鳡幼鱼全长、体重、存活率、肠绒毛高度和肌层厚度均显著高于W15组(P<0.05)。鳡36 dph时,W22组鳡幼鱼特定生长率最高,W29组鳡幼鱼存活率最高。在驯食期间,当猎物体高与捕食者口裂宽相等时,捕食者全长是猎物全长的1.5倍左右,猎物和捕食者的关系为TL猎物=0.53×T_(L捕食者)+3.63(T_(L指全长))。在驯食完成后,生长快(FB)鳡幼鱼胰蛋白酶比活力显著高于生长慢组(FS),淀粉酶、脂肪酶、碱性磷酸酶比活力显著低于FS组。FB与FS组鳡幼鱼差异表达基因主要显著富集在PPAR信号通路、脂肪酸合成与代谢等脂质代谢通路,FABP7、FAS、CPT1等脂质代谢相关基因的表达具有显著差异。综上,鳡幼鱼在22—29日龄开始驯食能够取得最佳驯食效果;驯食期间将规格大于群体平均全长1.5倍左右的个体筛出能有效预防残食发生,提高存活率;驯食后生长差异可能与肠道消化酶比活力和脂质代谢差异有关。研究为鳡幼鱼驯食及驯食后苗种培育提供指导,为肉食性鱼类苗种驯食相关研究提供参考。

The yellowcheek carp(Elopichthys bambusa)is a large and aggressive carnivorous fish.Weaning represents a significant bottleneck in the large-scale aquaculture of yellowcheek carp.To investigate the appropriate timing for weaning and its effects on growth and intestinal health,15 days post-hatching(dph)weaning group(W15),a 22 dph weaning group(W22),and a 29 dph weaning group(W29)were set up to wean yellowcheek carp at 15 dph,22 dph,and 29 dph,respectively.We investigated the effects of weaning starting time on growth,survival,and intestinal development.The results showed that the total length,body weight,and survival rate of juvenile yellowcheek carp in the W22 and W29 groups were significantly higher than that in the W15 group at different periods.Additionally,intestinal villus height and muscle thickness were significantly higher in the W22 and W29 groups compared to the W15 group.At 36 dph,the W22 group exhibited the highest specific growth rate,while the W29 group had the highest survival rate.During the weaning period,when the prey’s body depth equaled the predator’s mouth width,the predator’s total length was approximately 1.5 times the prey’s total length,described by the relationship T_(Lprey)=0.53×T_(Lpredator)+3.63.Moreover,the trypsin activity in the fast-growing(FB)group of juvenile yellowcheek carp was significantly higher than that in the slow-growing(FS)group,whereas the activity of amylase,lipase,and alkaline phosphatase were significantly lower.Deferentially expressed genes in the FB and FS groups were significantly enriched in lipid metabolic pathways,including the PPAR signaling pathway,fatty acid metabolism,and fatty acid biosynthesis.qPCR confirmed significant differences in the expression of four lipid metabolism-related genes:FABP7,FAS,CPT1,and GYS2.The results indicated that initiating weaning at 22—29 dph can obtain the best growth and survival outcomes.Additionally,selecting larger individuals,approximately 1.5 times the average length of the population,can prevent cannibalism and improve survival rate during weaning.The growth performance of juvenile yellowcheek carp post-weaning may be linked to differences in intestinal digestive enzyme activities and lipid metabolism ability.This study provides important gui dance for the weaning and post-weaning cultivation of juvenile yellowcheek carp and may inform weaning research for other carnivorous fish species.