Rumen epithelium-associated microbiome from German Holstein calves fed two different milk replacer feeding intensities

In dairy calves, feeding milk replacers has a major impact on metabolism, immune system, and microbial composition and influences the animals' welfare and lifetime performance. The 14 newborn female calves examined in this study received either 10% (n = 7) or 20% (n = 7) milk replacer of their body weight pre-weaning and had ad libitum access to grass hay and concentrate pellets. The rumen epithelium (papillae from the left lateral site) of the calves was sampled by rumen cannulation at week 9 (pre-weaning) and week 22 (post-weaning) of age. To investigate the composition of the microbiota, microbial DNA was isolated and analysed by 16S sequencing.