Understanding the gut microbiota characteristics of endangered species such as the Eurasian otter (Lutra lutra), especially in their early stages of life, could be essential for improving their management and ex situ conservation strategies. Here, we analyzed the gut microbiota diversity, composition, and function of captive Eurasian otters at different ages using high-throughput 16S rRNA gene sequencing. We found that: (1) Clostridiaceae was abundant in all age stages; (2) Lactococcus in cubs is thought to predominate for digesting milk; (3) bacteria associated with amino acid metabolism increase with age, while bacteria associated with carbohydrate metabolism decrease with age, which is likely due to decrease in dietary carbohydrate content (e.g., milk) and increase in dietary protein contents (e.g., fishes) with age; and (4) fish-related bacteria were detected in feces of healthy adults and juveniles. Overall, the gut microbiota of captive Eurasian otters was taxonomically and functionally different by age, which is thought to be attributed to the difference in the diet in their life stages. This study provided baseline information regarding the gut microbiota of Eurasian otters for the first time and contributes to improvement in their management in captivity.

了解欧亚水獭 ( Lutra lutra )等濒危物种的肠道微生物群特征，尤其是在它们生命的早期阶段，对于改善它们的管理和异地保护策略可能至关重要。在这里，我们使用高通量 16S rRNA 基因测序分析了不同年龄圈养欧亚水獭的肠道微生物群多样性、组成和功能。我们发现： (1) 梭菌科在各个年龄阶段均丰富；(2)乳球菌在幼崽中，被认为主要用于消化牛奶；(3) 与氨基酸代谢相关的细菌随着年龄的增长而增加，而与碳水化合物代谢相关的细菌随着年龄的增长而减少，这可能是由于膳食碳水化合物含量（如牛奶）减少和膳食蛋白质含量（如鱼类）增加所致年龄; (4) 在健康成人和青少年的粪便中检测到与鱼类有关的细菌。总的来说，圈养欧亚水獭的肠道微生物群在分类学和功能上因年龄而异，这被认为是由于它们生命阶段饮食的差异。这项研究首次提供了有关欧亚水獭肠道微生物群的基线信息，并有助于改善它们的圈养管理。