配合饲料替代活饵对鳜生长性能、消化功能及小肽转运载体基因表达的影响

Effects of replacing live bait with compound feed on growth, digestion and expression of small peptide transporter(PepT1) gene of Siniperca chuatsi

  • 摘要: 【目的】比较投喂活饵鱼和配合饲料对鳜(Siniperca chuatsi)生长性能、消化功能及肠道PepT1基因表达的影响,明确其摄食配合饲料后的消化、吸收生理变化,为提高鳜对配合饲料的利用效果提供理论依据。【方法】挑选驯化鳜鱼苗(初始平均体质量5.92±1.41 g)和未驯化鳜鱼苗(初始平均体质量6.06±1.73 g)各300尾,分别使用配合饲料或活饵鱼喂养30 d,饲养结束后测定分析其生长性能、肌肉成分、消化道结构、消化酶活性及小肽转运载体(PepT1)基因表达情况。【结果】配合饲料组鳜的终末平均体质量、总摄食量、尾摄食量、饵料系数、日增重量、日增重率、特定生长率、蛋白质效率、存活率及肥满度均极显著低于活饵鱼组鳜(P< 0.01,下同),脏体比和肝体比显著高于活饵鱼组鳜(P< 0.05,下同)。以配合饲料替代活饵鱼投喂鳜,对其肌肉成分有明显影响,具体表现为鳜肌肉水分含量极显著低于活饵鱼组鳜,粗蛋白含量显著高于活饵鱼组鳜。在消化酶活性方面,配合饲料组鳜的幽门盲囊胰蛋白酶活性极显著低于活饵鱼组鳜,幽门盲囊脂肪酶活性显著低于活饵鱼组鳜,但肝脏和肠道中的消化酶活性无显著差异(P> 0.05,下同);配合饲料组鳜的肝细胞排列松散,肝细胞间有脂肪堆积,胃、肠道肌层及胃黏膜下层厚度极显著小于活饵鱼组鳜,肠道单个褶皱绒毛层杯状细胞数极显著多于活饵鱼组鳜,幽门盲囊褶皱间距极显著大于活饵鱼组鳜。PepT1基因在鳜肠道中的相对表达量表现为前肠>中肠>后肠,且在前肠表现为配合饲料组鳜极显著低于活饵鱼组鳜,在中肠和后肠则表现为差异不显著。【结论】鳜对配合饲料的摄食量和利用率均低于活饵鱼,消化道组织结构及其消化酶活性也因摄食配合饲料发生适应性变化。投喂配合饲料显著影响鳜的消化吸收功能和生长性能,因此,还需针对其摄食和代谢特性进一步改良配合饲料的营养组分或优化鳜的配合饲料驯化技术。

     

    Abstract: 【Objective】To compare the differences in growth performance, digestive function and expression of PepT1 gene in intestine of Siniperca chuatsi fed by live bait and compound feed, and clarify the physiological changes of digestion and absorption after feeding compound feed, and provide theoretical basis for improving the utilization effect of compound feed for S.chuatsi.【Method】A total of 300 individuals with feeding domestication(average initial weight of 5.92±1.41 g) and 300 individuals without feeding domestication(average initial weight of 6.06±1.73 g) were selected and fed with compound dietand live bait fish for 30 d respectively.The growth performance, muscle composition, structure of digestive tract, digestive enzyme activity and small peptide transporter(PepT1) gene expression were determined and analyzed after feeding.【Result】The final mean body weight, total food intake, average individual feed intake, feed coefficient, daily gain, daily gain, special growth rate, protein efficiency, survival rate and fatness of the compound feed group were extremely significantly lower than thoseof the live bait group(P< 0.01, the same below), while the organbody weight ratio and liver-body weight ratio were significantly higher than thoseof the live bait group(P< 0.05, the same below).The muscle composition of live bait fish was obviously affected by feeding compound feed instead of live bait.The moisture content of muscle was extremely significantly lower than that of the live bait group, and the crude protein content of muscle was significantly higher than that of the live bait group, when compound feed replacedlive bait to feed.In terms of digestive enzyme, activity of trypsin in the pyloriccaecum in the feed group were extremely significantly lower than that in the live bait group, and that of lipase were significantly lower than that in the live bait group, but there was no significant difference in digestive enzyme activity of liver and intestine(P> 0.05, the same below).Loose liver cells were observed in compound feed group, the fat accumulation among liver cells was detected, the thickness of stomach, intestinal muscle layer and gastric submucosa in the compound feed group was extremely significantly lower than those in the live bait group.The number of goblet cell in single villuswas extremely significantly more than that in live bait group, and the fold spacing of pyloric caecum was extremely significantly higher than that in the live bait group.The relative expression level of gene PepT1 in the intestine of each group was foregout> midgut> hindgut, and the expression level in foregut of compound feed group was extremely significantly lower than that in the live bait group, but there was no significantly difference in the midgut and hindgut.【Conclusion】Feed intake and utilization of compound feed are lower than those of live bait fish, and the structure of the digestive tract, digestive enzymes activity also change adaptively due to the compound feed, and it significantly affects the function of digestion and absorption and growth performance.Thus, it is necessary to further improve the nutritional components of feedor optimize the domestication technology of S.chuatsi according to its feeding and metabolic characteristics.

     

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