Abstract The first step for assessing and refining the nutritional requirements during the larval and early juvenile stages of a fish is the study of the ontogeny of digestive system functionality. The combination of these studies with ecological and anatomical knowledge of the species of interest establishes the base for facing one of the major aquaculture challenges: promoting larvae growth and survival. Considering this, changes in the activity of the main digestive (pancreatic and intestinal) enzymes during larval development of the agastric South America pejerrey (Odontesthes bonariensis) were described in the present work. Digestive enzymes for protein, lipid, and carbohydrate hydrolysis were present from the first-week post-hatching (6.85 ± 0.07 mm total length, TL). Changes in the activity of trypsin, chymotrypsin, and alkaline protease indicated that the exocrine pancreas in pejerrey achieves its functional development at the 2nd week post-hatching (9.22 ± 0.17 mm TL). Interestingly, α-amylase and maltase total activity progressively increased over development, suggesting that gradual incorporation of dietary carbohydrates in a feeding protocol may have a protein-sparing effect, as well as a cheap and fast way to obtain energy for the development and growth of pejerrey. The analysis of intestinal enzymes revealed that the typical shift between intracellular and luminal protein digestion that occurs during larval development in gastric species does not take place in pejerrey, indicating that in agastric species intracellular protein digestion plays a major role in comparison to luminal digestion during larval development. Contrary to gastric species, our results suggest that the ratio of alkaline phosphatase to leucine-aminopeptidase for evaluating gut maturation in agastric species is not recommended, and other parameters should be measured when evaluating the maturation process in fish larvae from this group of species.

中文翻译：

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pejerrey (Odontesthes bonariensis) 个体发育过程中的消化酶活性

摘要 评估和提炼鱼类幼体和幼鱼早期营养需求的第一步是研究消化系统功能的个体发育。这些研究与感兴趣物种的生态学和解剖学知识相结合，为应对水产养殖面临的主要挑战之一奠定了基础：促进幼虫生长和存活。考虑到这一点，在本工作中描述了在胃南美洲 pejerrey (Odontesthes bonariensis) 幼虫发育过程中主要消化 (胰腺和肠道) 酶活性的变化。在孵化后的第一周（总长度为 6.85 ± 0.07 毫米，TL）就存在蛋白质、脂质和碳水化合物水解的消化酶。胰蛋白酶、糜蛋白酶活性的变化，和碱性蛋白酶表明，pejerrey 的外分泌胰腺在孵化后第 2 周（9.22 ± 0.17 mm TL）实现其功能发育。有趣的是，α-淀粉酶和麦芽糖酶的总活性在发育过程中逐渐增加，这表明在喂养方案中逐渐加入膳食碳水化合物可能具有节约蛋白质的作用，以及一种廉价、快速的获得能量用于发育和生长的方法。佩杰里。肠道酶的分析表明，在胃物种幼虫发育过程中发生的细胞内和腔内蛋白质消化之间的典型转变在 pejerrey 中没有发生，这表明与幼虫期间的腔内消化相比，胃内物种的细胞内蛋白质消化起主要作用发展。与胃的种类相反，