Abstract: Food diversity and seasonal variation in food quality are key environmental challenges for wild small mammals. Lactation represents one of the most energy-demanding life-history stages, during which dietary preferences are critical for meeting maternal energy needs and ensuring reproductive success. Using energy budget analysis and 16S rRNA gene sequencing, we examined the impacts of high-protein, high-fat, and high-fiber diets during lactation on energy intake, reproductive output, and gut microbiota in striped hamsters (Cricetulus barabensis). The hamsters showed a significant preference for high-fat food, which accounted for 59. 8% of total intake in the non-reproductive period and rose to 78. 1% during lactation. In contrast, control, high-protein, and high-fiber foods comprised only 8. 4%, 3. 3%, and 10. 1% of intake, respectively. Lactating females exhibited significantly increased food intake and resting metabolic rate compared to the non-reproductive period. However, their maximum intake of each food type did not exceed that of the control group. Females on high-protein or high-fiber diets showed significantly lower lactation output and offspring body weights than those in the control and high-fat groups. Digestive system weight increased significantly during lactation. In the high-fiber group, both large intestine and cecum weights were significantly higher than in other groups. At the phylum level, Firmicutes and Bacteroidetes dominated the gut microbiota. Compared to the control group, the highprotein group had decreased Firmicutes and increased Bacteroidetes abundance. The alpha diversity (ASVs number, Chao1 index and Shannon index) was significantly decreased in the hamsters fed with high-fiber and high-protein diet, while it was not significantly changed in the hamsters fed with high-fat food diet and those fed with various types of food. These findings suggest that lactating striped hamsters exhibit strong dietary preferences. The higher specific dynamic action of high-protein food may explain their lower intake. Digestive system plasticity may also reach a limit, constraining dietary choices. The hamsters that were fed a high-fiber and high-protein diets failed to meet the energy needs of their offspring despite increasing their own energy intake, which was partly due to the significant decrease in milk energy output. These changes may be related to a significant decrease in the alpha diversity of the gut microbiota. Seasonal changes in food availability play a key role in shaping reproductive strategies in wild small mammals, and exclusive reliance on high-protein or high-fiber diets may compromise maternal reproductive performance.

Key words: Food quality, Food intake, Lactation, Milk energy output, Seasonal reproduction

摘要： 食物的多样性和食物质量的季节性变化是野生小型哺乳动物必须应对的主要环境因子。哺乳期是动物能量需求最高的生活史阶段之一，在此期间对不同食物的选择偏好对确保哺乳期母体的能量需求和繁殖成功具有重要影响。本研究采用能量收支法和微生物16S rRNA基因测序，探讨了黑线仓鼠（Cricetulus barabensis）在哺乳期分别摄取高蛋白、高脂肪和高纤维食物对其能量摄入、繁殖输出及肠道菌群的影响。结果发现，黑线仓鼠显著偏好高脂食物，非繁殖期摄取高脂食物占总摄食量的59.8%，哺乳期高达78.1%，而标准维持鼠食物、高蛋白和高纤维食物仅占8.4%、3.3%和10.1%。与非繁殖期相比，哺乳期母体摄食量显著增加，静息代谢率亦显著提高，但自由选择食物的母体最大摄食量均未超过对照组水平。摄取高蛋白和高纤维食物母体的泌乳输出、幼体的胎仔质量均显著低于对照组和摄取高脂食物组。与非繁殖期相比，哺乳期母体的消化系统质量显著增加，摄取高纤维食物组的大肠和盲肠质量显著高于其他各组。盲肠厚壁菌门（Firmicutes）和拟杆菌门（Bacteroidota）为门水平上的优势菌群，与对照组相比，高蛋白食物组厚壁菌门相对丰度降低，而拟杆菌门相对丰度升高；高纤维食物组和高蛋白食物组α多样性（ASVs数量、Chao1指数和Shannon指数）显著降低，而高脂食物组和自由选择食物组未发生显著变化。结果表明，哺乳期黑线仓鼠对食物的选择具有显著的偏好，高蛋白食物具有较高食物特殊动力效应，可能是摄取比例较低的主要原因；消化系统可塑性可能达到瓶颈，在一定程度上限制了动物的选择偏好。摄取高纤维和高蛋白食物的母体未能通过增加能量摄入满足幼体的能量需求，泌乳能量支出显著降低是主要原因之一，这些变化可能与肠道微生物α多样性显著降低有关。食物资源可利用性的季节性变化对野生小型哺乳动物的季节性繁殖策略具有重要影响，仅利用高蛋白和高纤维食物会降低母体的繁殖价值。

关键词: 食物质量, 摄食量, 哺乳期, 泌乳支出, 季节性繁殖