The ontogeny of the gastrointestinal tract of the hybrid between female rainbow trout, RT (Oncorhynchus mykiss) and male Caspian brown trout, CBT (Salmo trutta caspius) was compared to the parental species. Larvae were collected for histology and enzymatic assays (amylase, lipase and trypsin) at 3, 6, 9, 12, 15, 18, 21, 26, 31, 35, 40 and 45 days post‐hatch (dph). The development of the gastrointestinal tract (GI‐tract) and the onset of digestive enzyme production was variable between groups. The GI‐tract post‐hatch was a relatively simple tubular structure, and a rudimentary oesophagus was differentiated from other regions at 3 dph in all studied groups. The pyloric caeca and the U‐shaped stomach were clearly visible at 26, 35 and 40 dph in RT, triploid hybrid and CBT, respectively. An abrupt increase in trypsin activity at 31, 35 and 45 dph was identified in CBT, RT and the triploid hybrid, respectively. The increasing activity of trypsin and decreasing activity of lipase during larval development suggests that the CBT, RT and triploid hybrid rely more on dietary proteins than lipids with increasing age. The hybrid grew better and had a faster GI‐tract development than CBT, while RT performed best overall.

中文翻译：

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cor cor x Salmo trutta caspius♂三倍体杂种与其亲本物种消化道的比较个体发育。

雌性虹鳟RT（Oncorhynchus mykiss）和里海雄性棕鳟CBT（Salmo trutta caspius）之间的杂种的胃肠道发育）与亲本物种进行了比较。在孵化后（dph）第3、6、9、12、15、18、21、26、31、35、40和45天收集幼虫进行组织学和酶学检测（淀粉酶，脂肪酶和胰蛋白酶）。两组之间胃肠道（GI-tract）的发育和消化酶产生的开始是可变的。胃肠道孵化后是一个相对简单的管状结构，在所有研究组中，食管的原始食道均以3 dph的速率与其他区域区分开。在RT，三倍体杂种和CBT中，幽门盲肠和U型胃分别在26、35和40 dph时清晰可见。分别在CBT，RT和三倍体杂种中鉴定到31、35和45 dph时胰蛋白酶活性突然增加。在幼虫发育过程中，胰蛋白酶的活性增加和脂肪酶的活性降低表明，随着年龄的增长，CBT，RT和三倍体杂种更依赖饮食蛋白，而不是脂质。混合动力车比CBT更好地生长，并具有更快的胃肠道发育能力，而RT总体上表现最好。