In the United States, 36.5% of women between the ages of 20 and 39 years are obese. This obesity results in not only metabolic disorders including type II diabetes and cardiovascular disease, but also impaired female fertility. Systemic and tissue-specific chronic inflammation and oxidative stress are common characteristics of obesity. This is also true in the ovary. Several studies have demonstrated that pro-inflammatory cytokines and reactive oxygen species alter estrous cyclicity, steroidogenesis and ovulation. Inflammation and oxidative stress also impair meiotic and cytoplasmic maturation of the oocyte which reduces its developmental competence for fertilization and pre-implantation embryo development. Interestingly, there is recent evidence that obesity-and/or polycystic ovary syndrome (PCOS)-dependent changes to the gut microbiome contributes to ovarian inflammation, steroidogenesis and the expression of mRNAs in the oocyte. However, several gaps remain necessitating future studies to identify inflammation, oxidative stress and gut microbiome mechanisms that reduce ovarian function and oocyte quality.Reproduction (2019) 158 R79-R90

Increasing evidence from human and other animal species supports the existence of a commensal microbiota in semen and that this seminal microbiota may influence not only sperm quality and fertility but also female reproduction. Seminal microbiota in bulls and its evolution and factors shaping this community, however, remain largely underexplored.

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We hypothesized that yearling bulls selected for a 28‐d breeding season would have reduced sperm concentrations and morphology, and have increased seminal plasma concentrations of pro‐inflammatory cytokine interleukin‐8 (IL‐8). Yearling bulls were selected based on a breeding soundness examination (BSE) at approximately 415 d of age and contained at least 750 million sperm in the ejaculate, with 12 bulls randomly selected for breeding (BREEDERS) and 12 bulls not selected for breeding (NON‐BREEDERS). After a 28‐d breeding period, all bulls underwent a BSE. Plasma and seminal plasma were collected at each time point for analysis. Data were analysed utilizing either the MIXED or GLIMMIX procedures with repeated measures in SAS with breeding group, age and the interaction as fixed effects. Sperm concentration per ml of ejaculate was reduced (p < .05) in yearling bulls used for breeding compared with those not used for breeding at the end of the breeding season. Seminal plasma IL‐8 concentrations in yearling bulls used for breeding were increased (p < .05) after the breeding season compared with bulls not used for breeding. Taken together, yearling bulls selected for a 28‐d breeding season have reduced sperm production per ml of an ejaculate and increased inflammatory response in the seminal plasma that can lead to impaired breeding response if they are to be used for more than 30 d of breeding.

The UNL physiology herd has a population of cows that secrete excess androstenedione (A4) in follicular fluid. These High A4 cows are less fertile, have irregular cycles, are often anovulatory, and have similar characteristics to women with Polycystic Ovary Syndrome (PCOS). Ovarian cortex cultures of High A4 cows secrete more A4 than controls. High A4 cows reached puberty 45 d earlier than control cows. Thus, we hypothesized that heifers reaching puberty earlier were predisposed to become High A4 cows. To test this hypothesis, we collected blood plasma from weaning to breeding (2012–2017) in 611 heifers. A custom SAS program was developed using progesterone >1ng/ml to identify four distinct puberty groups: 1) Early Puberty- 317.0 ± 3.6 days of age (doa) with continued cyclicity (n = 143); 2) Typical Puberty- 378.4 ± 2.1 doa with continued cyclicity (n = 279); 3) Start-Stop Puberty- 265.3 ± 4.1 doa with discontinued cyclicity (n = 91); and 4) Non-Cycling- no P4≥1ng/ml (n = 98). The pattern of Sex Hormone Binding Globulin (SHBG) was increased prior to puberty in Early and Typical and reduced in Start-Stop and Non-Cycling heifers. Early heifers (4.9) had greater prebreeding reproductive tract scores, followed by Typical (4.7), Start-Stop (4.5), and Non-Cycling (4.0) heifers. At breeding, all heifers that showed estrus in response to PGF2a were artificially inseminated. Typical (78.9%), Early (79.5%) and Start-Stop heifers (50.3%) had a greater response compared to Non-Cycling heifers (12.6%). All heifers were exposed to bulls, and overall pregnancy rate was not different. However, a greater percentage of Typical (57.9%), Early (51.0%), and Start-Stop (45.2%) heifers calved in the first 21 d of the calving season compared to Non-Cycling (20.9%). Start-Stop (3.0ng/ml) and Non-Cycling (4.2ng/ml) heifers had increased A4 in ovarian cortex culture media compared to Typical (0.062ng/ml) or Early (0.091ng/ml) puberty heifers. Greater A4 produced by ovarian cortex of Start-Stop and Non-Cycling heifers, irregular cycles and reduced calves in the first 21 d indicates these females may be predisposed to becoming High A4 cows with decreased fertility.

Background: Increasing evidence supports the existence of a microbial community in bovine semen, and that this seminal microbiota may influence not only the male fertility but also female reproduction. In this study, we evaluated the seminal and fecal microbiota in yearling beef bulls fed a common diet to achieve moderate (1.13 kg/d) or high (1.80 kg/d) rates of weight gain. Semen samples were collected on days 0 and 112 of dietary intervention (n = 19/group) as well as post-breeding (n = 6/group) using electroejaculation and the microbiota was assessed using 16S rRNA gene sequencing, qPCR, and culturing. The fecal microbiota was also evaluated and its similarity with seminal microbiota assessed. A subset of seminal bacterial isolates (n = 33) was screened for resistance against 28 antibiotics.Results: A complex and dynamic microbiota was detected in bovine semen, and the community structure was affected by sampling time (R2 = 0.16, P < 0.001). Microbial richness increased from d 0 (ASVs, 253 ± 12) to d 112 (293 ± 14) (P < 0.05). Microbial diversity did not change during pre-breeding but increased after breeding (P < 0.05). Fusobacteriota, Bacteroidota, Firmicutes and Actinobacteriota were dominant in the seminal microbiota, and their abundance changed over time and following breeding (P < 0.05). Seminal microbiota remained unaffected by the differential rate of gains, and its overall composition was distinct from fecal microbiota, with only 6% of the taxa shared between them. The fecal microbiota did not differ between the two dietary treatments at d 112 and post-breeding but changed over time from d 112 to post-breeding (P < 0.05). A total of 364 isolates from 49 different genera were recovered under aerobic and anaerobic culturing. Among these seminal isolates were pathogenic species associated with respiratory disease, liver abscesses and reproductive infections, as well as those resistant to several antibiotics. Conclusions: Our results suggest that bovine semen harbors a rich and complex microbiota which changes over time and in response to breeding activity but appears to be resilient to differential gains achieved via a common diet. Seminal microbiota is distinct from the fecal microbiota and harbors potentially pathogenic and antibiotic-resistant bacterial species.

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