Relative abundance of different species of microorganisms in different parts of the digestive tract of calves during the first four days after birth.

<p>The abundance of <i>Methanomicrobiales mobile</i>, <i>Methanococcales votae</i>, <i>Methanobrevibacter</i> spp. and <i>Geobacter</i> spp. was determined in (A) rumen fluid, (B) rumen tissue, (C) abomasum, (D) cecum fluid, (E) cecum tissue, and (F) feces of calves of 0 days old (blue bars), 1 day old (orange bars), 2 days old (grey bars), and 3 days old (yellow bars). Abundance, as Log₁₀ copy number per μl of 16S ribosomal DNA, is expressed relative to the lowest value among all species. Data are means ± SEM (n = 3). For each species, data without a common letter are significantly different (ANOVA, <i>P</i> < 0.05). Note the logarithmic scale of the y-axis.