The impact of pasteurization on the microbiota in bovine milk and calf feces

Pasteurization is a conventional method to reduce pathogen transmission from milk to calves. Previous studies primarily focused on the effects of pasteurized colostrum or short-term pasteurized milk feeding on neonatal dairy calves. This study examines the impact of continuous pasteurized milk feeding on early growth and the gut microbiome in dairy calves. Fecal samples were collected from 15 newborn dairy calves over one month, using high-throughput sequencing and microbial cultivation to analyze microbiome variations. Continuous feeding of pasteurized milk did not adversely affect growth performance but significantly reduced the abundance of L. reuteri in feces, likely due to the depletion of microbial resources from heat treatment. Extensive cultivation of Lactobacillus from milk and feces identified 40 distinct clusters out of 218 isolates using Rep-PCR. Whole-genome sequencing of 40 L. reuteri strains confirmed the presence of shared isolates in milk and the hindgut of calves. These L. reuteri isolates displayed a broad range of capabilities in metabolizing various oligosaccharides, including FOS, GOS, and inulin, contributing to early-life carbohydrate metabolism in dairy cattle. When optimizing calf growth strategies, it is essential to consider the impact of pasteurized milk on gut microbiota and the potential role of combined probiotics in maintaining intestinal health.

巴氏灭菌（Pasteurization）是减少牛乳向犊牛传播病原体的常规手段。既往研究多聚焦于巴氏灭菌初乳或短期巴氏灭菌牛乳饲喂对新生乳用犊牛的影响。本研究旨在探究持续饲喂巴氏灭菌牛乳对乳用犊牛早期生长性能与肠道微生物组（gut microbiome）的影响。研究周期为1个月，共采集15头新生乳用犊牛的粪便样本，通过高通量测序（high-throughput sequencing）与微生物培养技术分析微生物组的变化情况。持续饲喂巴氏灭菌牛乳未对犊牛生长性能产生负面影响，但显著降低了粪便中罗伊氏乳杆菌（L. reuteri）的丰度，这可能源于热处理对微生物资源的耗竭。通过对牛乳与粪便中的乳酸杆菌进行大规模培养，结合Rep-PCR技术对218株分离菌株进行分型，共得到40个不同的聚类簇。对40株罗伊氏乳杆菌（L. reuteri）进行全基因组测序（whole-genome sequencing）后证实，牛乳与犊牛后肠中存在同源分离菌株。上述罗伊氏乳杆菌分离株可代谢多种低聚糖，包括低聚果糖（FOS）、低聚半乳糖（GOS）与菊粉（inulin），这有助于乳用犊牛早期的碳水化合物代谢。在优化犊牛生长饲喂策略时，需充分考虑巴氏灭菌牛乳对肠道微生物群的影响，以及复合益生菌在维持肠道健康中的潜在作用。