Fig. 2.

Overview of study design of 46 studies included in this systematic review. Each column depicts the study design of a paper which was represented with a paper identification number (ID) (Additional File 2). The rows describe the data extracted from the paper, including year of publication, sequencing platform, sequencing region, WHO geographical region, cattle breed, sample size, specimen type, microbiome DNA isolation method, taxonomy identification database and rationale. The colour codes for each data categories are listed in the Figure legend