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Despite differences in gut physiology and morphology, both humans and cattle require a functional gut microbiome in early life. Evidence suggests that both species acquire gut microbes prior to birth, likely from a maternal source, indicating the use of similar mechanisms and timing for fetal gut colonization. Unlike mouse models, cattle share a similar gestation length, parity, and placental microbiome characteristics to humans. The large size of calves allow for contamination-protected sampling of the gut, vagina, and uterus, which would typically require invasive procedures in human cohorts. The ruminant placenta also exhibits a larger degree of separation between maternal and fetal physiology, necessitating a direct and explicit route by which microbes may access the fetal gut. These and other features permit cattle to act as a translational model for early gut colonization. However, cattle do not share similar placental morphology, gut function, or early immune system interactions with humans, creating barriers to their use as a biomedical model. Identifying similarities and differences between humans and cattle may outline the most important functions of the placental and fetal gut microbiomes, indicate the source of these microbes, and highlight the role of maternal or environmental influences upon fetal health across species.

The increasing demand for meat and milk products due to the rising population, coupled with limited resources, requires increased efficiency of livestock. The microbiome within the rumen allows ruminant species to convert low-quality forages into volatile fatty acids (VFA) that are absorbed and digested by the animal to be used as an energy source. Understanding the development of microorganisms within the rumen is of interest due to their effects on host health, energy, performance, and efficiency (Flint and Bayer, 2008; Guan et al., 2008). Evidence suggests that colonization of the calf gastrointestinal tract may occur prior to birth due to the presence of bacteria in the meconium (Alipour et al., 2018). In addition, the establishment of the bacterial communities within the rumen occurs sequentially (Jami et al., 2013; Rey et al., 2014); however, little is known about the relationship and influence of the maternal rumen microbiome on subsequent development of the calf rumen microbiome and VFA production. Research in humans (Biasucci et al., 2010) and ruminants (Cunningham et al., 2018) suggests that there is a maternal influence on gut microbiome development, including mode of delivery and nutrition. In addition, microbial populations established early in life have the ability to affect the health and performance of the adult animal, suggesting the potential for programming of the microbiome (Abecia et al., 2013). Thus, we hypothesized that the cow maternal rumen microbiome would influence colonization of the calf rumen microbiome. Our objective was to relate the rumen microbiome of the cow prior to parturition (RFC) and at weaning (RFCw) to the calf’s meconium microbiome (M) and calf rumen microbiome at birth (RFd1), day 2 (RFd2), day 28 (RFd28), and weaning (RFNw).

Subclinical mastitis is a common intramammary disease in sheep production systems. Expenses associated with compromised animal performance, therapeutic interventions, and decreased ewe longevity make efforts to minimize its prevalence worthwhile. The objectives of this study were to 1) quantify the prevalence of subclinical mastitis throughout lactation, 2) evaluate the impact of bedding treatments on subclinical mastitis during early lactation, 3) evaluate the efficacy of prophylaxis and feed restriction during weaning on subclinical mastitis cure rates, and 4) identify levels and types of antimicrobial resistance in milk-derived bacteria. Ewe milk samples were collected at days 1, 2, and 28 post-partum, weaning, and 3-d post-weaning for bacterial identification via culture-based methods. Staphylococcus spp. and Streptococcus spp. isolates were subjected to in vitro antimicrobial susceptibility testing. The overall prevalence of subclinical mastitis defined by culture growth ranged between 22% and 66% and differences were observed between post-weaning and days 1 and 28 milk samples. Commonly isolated bacteria include coagulase-negative staphylococci (CoNS; 59%), Bacillus spp. (35%), Mannheimia haemolytica (10%), Staphylococcus aureus (8%), Streptococcus spp. (5%), and Corynebacterium spp. (5%). Early milk samples (days 1 and 2) were compared between jug bedding treatment: jugs were recently vacated, cleaned, and dusted with barn lime before adding fresh straw (CLEAN) or jugs were previously vacated and fresh straw was added atop soiled bedding (SOILED). Jug bedding treatment did not affect the prevalence of subclinical mastitis, though CoNS had greater sulfadimethoxine resistance in SOILED isolates than CLEAN isolates (P = 0.03). Three different weaning treatments were used: ewes were injected with penicillin at weaning (PENN), ewes had restricted feed access 48 h prior to and 72 h post-weaning (FAST), or a combination of these treatments (COMBO). Weaning treatment did not affect the prevalence of subclinical mastitis or cure rate from weaning to 3-d post-weaning, though all PENN and no FAST milk S. aureus isolates were resistant against tetracycline (P = 0.08). Subclinical mastitis prevalence tended to decrease from weaning to post-weaning (P = 0.08). These data show that subclinical mastitis is common throughout lactation and the levels of antimicrobial resistance of bacteria isolated from ewe milk are generally low against commonly used antimicrobials.Subclinical mastitis is a common intramammary disease in livestock. Expenses associated with compromised animal performance, therapeutic interventions, and decreased ewe longevity make minimizing its prevalence worthwhile. The objectives of this study were to quantify the prevalence of subclinical mastitis, evaluate the impact of bedding treatments on subclinical mastitis, evaluate the efficacy of weaning treatments, and identify levels of antimicrobial resistance in milk-derived bacteria. The overall prevalence of subclinical mastitis was 45%. Common bacteria included coagulase-negative staphylococci (CoNS), Bacillus spp., Mannheimia haemolytica, Staphylococcus aureus, Corynebacterium spp., and Streptococcus spp. Early lactation milk samples were compared between jug bedding treatments: jugs were cleaned before adding fresh straw (CLEAN) or jugs had fresh straw added atop soiled bedding (SOILED). Jug bedding treatment did not affect the prevalence of subclinical mastitis, though did affect CoNS resistance to sulfadimethoxine. Three different weaning treatments were used: ewes were administered penicillin at weaning, ewes had restricted feed access at weaning, or a combination of the two treatments. Weaning treatment did not affect the prevalence of subclinical mastitis, though subclinical mastitis prevalence decreased post-weaning. Our data show that subclinical mastitis is generally prevalent throughout lactation, and the levels of antimicrobial resistance of bacteria isolated from ewe milk are generally low.

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 the parturition, meconium and rumen fluid were collected from the calf. Rumen fluid was collected again from the calf on day 2, day 28, and at weaning. The rumen fluid microbial profile and subsequent volatile fatty acid (VFA) profile were 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 day 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, day 2, and day 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.Developmental programming has highlighted important influences of maternal factors on offspring development. Recent research indicates a programming potential of the rumen microbiome and understanding this role as well as how inoculation occurs may allow beef producers to optimize management practices of gestating cows such that offspring performance is improved via the rumen microbiome. To investigate this, rumen fluid samples were collected from mature cows immediately prior to calving, from their calf immediately after calving with a meconium sample, day 2, and day 28 as well as collected from both dam and calf at weaning. The rumen and meconium microbiome of the newborn calf were similar to each other as well as to the cow rumen microbiome at weaning, although not to the cow rumen microbiome immediately prior to calving. The shared microbiome of the early calf gut highlight a common source of inoculation. The similarities with the cow rumen at weaning could indicate initiation of colonization occurs early in gestation. Results indicate there are shared microbial properties between the cow and calf rumen microbiome. This further supports the opportunity to alter the calf rumen microbiome to improve productivity through the management of the cow during gestation.

Simple Summary The purpose of this study was to explore the influence of maternal feed intake restriction on the microbiome of the reproductive tract and its subsequent colonization of the bovine fetal gut microbiome in utero. After sequencing the microbial DNA of the maternal vagina, placental tissues, and fetal gut, our data show the microbiome of the vagina and cotyledon remain relatively unaffected by feed intake restriction and mineral supplementation. The placental microbiome of feed restricted pregnancies was less diverse, and feeding using a mineral supplement did not impact these differences. However, mineral supplementation improved the richness of the fetal gut microbiomes regardless of feeding treatment, substantiating prior evidence that in utero mineral supplementation improves calf performance. The obtained results may offer insight into improving nutrient use of calves born to dams experiencing feed restriction. Abstract 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.

Understanding the development of the calf rumen microbiome is important in developing manipulation strategies to improve efficiency as the animal ages. We hypothesized that the cow maternal microbiome would influence the colonization of the calf rumen microbiome. Our objective was to relate the microbiomes of the cow rumen fluid (RFC) to the calf meconium (M) and calf rumen fluid (RFN) at twenty-eight days of age. Mature, multiparous Angus crossbred cows (n = 10) from the University of Wyoming beef herd were used in this study. Rumen fluid was collected from the cows prior to parturition. Immediately following parturition, meconium was collected from the calf and at 28 days post-parturition, rumen fluid was collected from the calves. Microbial DNA was isolated using a lysis buffer and mechanical bead-beating procedure and purified using the QIAamp DNA Stool Mini Kit (Qiagen). Amplicon sequencing of the 16S rRNA V4 region was completed on the MiSeq and analyzed with QIIME2. Both alpha and beta diversity were evaluated by sample type and day. Richness and evenness differed by sample type. The greatest richness and evenness was in RFC (q < 0.01) followed by RFN and M, which did not differ from each other (q ³ 0.5). Bray-Curtis and Jaccard beta diversity differed by each sample type (q < 0.01). These data indicate that the M and RFN do not differ in number and distribution of features, but the samples are compositionally different. Additionally, the RFC differed in both alpha and beta diversity from both calf samples. These profiles can be used to develop hypotheses for the pathway of colonization in the early gut yet still reflect the vast differences in the developmental stage between the cow rumen microbiome and the early calf gastrointestinal microbiome.