An analysis of sites within the maternal reproductive microbiome that potentially contribute to fetal gut microbial colonization, with a special focus on the comparison between humans and cattle.

In cattle, the rumen is an important site for the absorption of feed by-products released by bacterial fermentation, and variation in ruminal function plays a role in cattle feed efficiency. Studies evaluating gene expression in the rumen tissue have been performed prior to this. However, validating the expression of genes identified in additional cattle populations has been challenging. The purpose of this study was to perform a meta-analysis of the ruminal transcriptome of two unrelated populations of animals to identify genes that are involved in feed efficiency across populations. RNA-seq data from animals with high and low residual feed intake (RFI) from a United States population of cattle (eight high and eight low RFI) and a Canadian population of cattle (nine high and nine low RFI) were analyzed for differences in gene expression. A total of 83 differentially expressed genes were identified. Some of these genes have been previously identified in other feed efficiency studies. These genes included ATP6AP1, BAG6, RHOG, and YPEL3. Differentially expressed genes involved in the Notch signaling pathway and in protein turnover were also identified. This study, combining two unrelated populations of cattle in a meta-analysis, produced several candidate genes for feed efficiency that may be more robust indicators of feed efficiency than those identified from single populations of animals.

No abstract

Optimization of host performance in cattle may be achieved through programming of the rumen microbiome. Thus, understanding maternal influences on the development of the calf rumen microbiome is critical. We hypothesized that there exists a shared microbial profile between the cow and calf rumen microbiomes from birth through weaning. Specifically, our objective was to relate the calf’s meconium and rumen fluid microbiomes in early life to that of the cow rumen fluid prior to parturition and at weaning. Rumen fluid was collected from multiparous Angus crossbred cows (n = 10) prior to parturition and at weaning. Immediately following parturition, meconium and rumen fluid were collected from the calf. Rumen fluid was collected again from the calf at d 2, d 28, and at weaning. The rumen fluid microbial profile and subsequent volatile fatty acid (VFA) profile was characterized using 16S rRNA sequencing and gas liquid chromatography, respectively. Microbial data was analyzed using QIIME2 and the GLM procedure of SAS was used to analyze the VFA profile. Alpha diversity was similar in the early gut microbiome (meconium, rumen fluid at birth and d 2; q ≥ 0.12) and between the cow and calf at weaning (q ≥ 0.06). Microbial composition, determined by beta diversity, differed in the early rumen microbiome (rumen fluid at birth, d 2, and d 28; q ≤ 0.04) and VFA profiles complimented these results. There were similarities in composition between meconium, rumen fluid at birth, and rumen fluid from the cow at weaning (q ≥ 0.09). These data indicate successive development of the rumen microbiome and stabilization over time. Similarities between meconium and rumen fluid at birth potentially indicates in utero colonization of the calf gastrointestinal tract. Similarities in composition between the early calf rumen microbiome and the cow at weaning prompt an interesting comparison and area for future consideration in terms of identifying at what stage of gestation might colonization begin. Overall, this study provides insight into similarities between the cow and calf microbiomes and may be helpful in developing hypotheses for the pathway of colonization and programming potential in the early gut.

Feed intake restriction impacts both humans and ruminants in late gestation, although it is unknown whether this adverse maternal environment influences the microbiome of the reproductive tract, and through it, the colonization of the fetal gut. A 2 × 2 factorial design including a 70% feed intake restriction (feed restricted ‘FR’ or control diets ‘CON’) and mineral supplementation (unsupplemented ‘S−’ or supplemented ‘S+’) was used to analyze these effects in multiparous cows (n = 27). Vaginal swabs were obtained 60, 30, and 10 days prior to the estimated calving date, along with neonatal rumen fluid and meconium. Placental tissues and efficiency measurements were collected. Microbial DNA was extracted for 16S sequencing of the V4 region. Feed restriction decreased the diversity of the placental microbiome, but not the vagina, while mineral supplementation had little impact on these microbial communities. Mineral supplementation did improve the richness and diversity of the fetal gut microbiomes in relation to reproductive microbes. These differences within the placental microbiome may influence individual health and performance. Adequate maternal nutrition and supplementation yielded the greatest placental efficiency, which may aid in the establishment of a healthy placental microbiome and fetal microbial colonization.