Bacterial succession in the gut of pre-weaning dairy calves. bovine gut metagenome breed:crossbreed (Holstein x Gyr)

The bacterial community in the gastrointestinal tract (GIT) of livestock ruminants play important roles in influencing animal health and performance. However, little is known about the establishment of these bacterial communities during development of the GIT in pre-ruminant calves, as well as the changes in their structure and abundance as they transition to functional ruminants. Here, we used next-generation sequencing to characterize and assess changes in the bacterial communities in the rumen, jejunum, cecum and colon of 17 crossbred calves at four developmental stages (7, 28, 49 and 63 days old) that characterize the transition from a milk-based diet to solid concentrate at pre-weaning. This work adds new insights into bacterial colonization of the developing calf GIT and may be useful in formulating strategies to improve the health and performance of dairy calves pre-weaning.