Exposure to endotoxin during estrus alters the timing of ovulation and hormonal concentrations in cows

Potential mechanisms and therapeutic strategies for LPS-associated female fertility decline

As a major component of the outer membrane of Gram-negative bacteria, lipopolysaccharide (LPS) can be recognized by toll-like receptors (TLRs) and induce inflammation through MyD88 or the TIR domain-containing adapter-inducing interferon-β (TRIF) pathway. Previous studies have found that LPS-associated inflammatory/immune challenges were associated with ovarian dysfunction and reduced female fertility. However, the etiology and pathogenesis of female fertility decline associated with LPS are currently complex and multifaceted. In this review, PubMed was used to search for references on LPS and fertility decline so as to elucidate the potential mechanisms of LPS-associated female fertility decline and summarize therapeutic strategies that may improve LPS-associated fertility decline.

Retrospective evaluation of udder recovery of cows with subclinical mastitis following treatment with acoustic pulse technology (APT) on commercial dairy farms and its economic impact

Retrospective evaluation of udder recovery following treatment of the inflamed quarter with acoustic pulse technology (APT) of cows with subclinical mastitis was done on 4 Israeli commercial dairy farms. Here, we evaluated the APT treatment as a tool to manage subclinical mastitis and its economic consequences in commercial farms. Recovery of the infected glands following APT treatment was compared to the customary no-treatment (NT) for cows with subclinical mastitis. Over 2 years, 467 cows with subclinical mastitis were identified. Subclinical mastitis was defined by elevated somatic cell count (SCC; >1 × 106 cells/mL) in the monthly test-day milk sample; 222 cows were treated with APT and 245 cows were not treated and served as control. Differences between treatment groups in culling, milk quality, milk yield and bacterial elimination were analyzed. After treatment, cure from bacteria was calculated only for cows with pre-isolated bacteria. The percentage of sampled cows determined as cured (no bacterial finding) in the NT group was 32.7% (35/107) (30.9% Gram negative; 32.4% Gram positive) and in the APT-treated group, 83.9% (42/55) (89.4% Gram negative; 80.6% Gram positive). Culling rate due to mastitis was significantly lower (>90%) in the APT-treated vs. NT group. Recovery was 66.0% in the APT group compared to 11.5% in the NT group at 90 d post-treatment. Average milk volume per cow in the APT-treated group was 16.1% higher compared to NT cows. Based on the study, savings incurred by using APT to treat only subclinical cows per 100-cow herd can total $15,106/y, or $309 per treated subclinically infected cow.

Interval from Oestrus to Ovulation in Dairy Cows-A Key Factor for Insemination Time: A Review

This review describes the oestrus-to-ovulation interval, the possibility of predicting the time of ovulation, and the optimum time for insemination relative to oestrus in dairy cows. The duration of oestrus in dairy cows is approximately 8-20 h, with differences possibly related to the methods of oestrus detection and the frequency of observations. Most cows ovulate approximately 24-33 h after the onset of oestrus and 15-22 h after the end of oestrus. The interval from the preovulatory luteinising hormone (LH) surge to ovulation is approximately 4-30 h. Ovulation occurs when follicle diameter averages 18-20 mm. When it is possible to correctly determine the beginning of oestrus, artificial insemination can be performed utilizing the "a.m.-p.m. rule", and only one insemination may be applied. In cows with too long or too short oestrus-to-ovulation intervals, fertility can be compromised. One important factor that can alter the oestrus-to-ovulation interval is acute or chronic heat stress during the warm season. When there is a risk that insemination may occur too early or too late with respect to the time of ovulation, GnRH administration can be considered.

Impact of negative energy balance and postpartum diseases during the transition period on oocyte quality and embryonic development in dairy cows

Transition period is a critical time for dairy cows because a large proportion of clinical and subclinical diseases are observed in the first month after parturition. Occurrence of negative energy balance is associated with depressed immunity and these conditions can affect oocyte quality and further embryonic development. The aim of this study was to assess the effects of negative energy balance-associated disorders on in vitro embryo production (IVP) in dairy cattle. We hypothesized that subclinical metabolic and/or inflammatory disorders have a negative effect on oocyte developmental competence and morphokinetic parameters of the resulting embryos. The study was conducted on 30 lactating Holstein-Friesian cows which were assigned into four groups: healthy (HEAL, n = 6), metabolic disease (META, n = 8), inflammatory disease (INFL, n = 8), or combined metabolic and inflammatory disease (COMB, n = 8). Ovum pick-up (OPU) was performed twice weekly on all cows over a period of four weeks (n = 8 OPU sessions/cow) starting on the fifth week postpartum, and the collected oocytes were subjected to routine IVP. Donor's health status did not affect the number of oocytes/OPU or the recovery rate (p > 0.05). The number of quality 1 oocytes collected from INFL and COMB cows was lower compared to HEAL cows (p < 0.05). Also, the percentage of quality 1 embryos was reduced in META and COMB compared to HEAL cows (p < 0.05). Cleavage, blastocyst and hatching rates were similar among groups (p > 0.05). Presence of disease did not affect the time required by zygotes to reach specific developmental stages, as recorded by means of time-lapse monitoring. Nevertheless, there was a higher probability of direct cleavage after IVF in oocytes of COMB cows compared to those of HEAL cows (p < 0.05). In conclusion, oocytes and embryos derived from dairy cows diagnosed with subclinical metabolic and/or inflammatory diseases during the transition period showed reduced quality but similar developmental potential and morphokinetics when compared to healthy cows. These results shed light on the consequences of subclinical disease on embryonic development in dairy cows which might be important for embryo transfer programs.

Induced endometritis in early lactation compromises production and reproduction in dairy cows

Objectives of this experiment were to study the effect of infusing utero-pathogenic bacteria to induce endometrial inflammation on productive performance in early lactation and subsequent reproduction. Although endometritis is associated with perturbed reproduction, numerous factors may contribute to the observed association. It was hypothesized that induced endometrial inflammation, resulting in localized and systemic inflammatory responses, compromises production and reproduction. Holstein cows without clinical disease and with less than 18% polymorphonuclear leukocytes (PMN) in endometrial cytology on d 31 ± 3 postpartum had their estrous cycle synchronized. Cows were blocked by parity and genomic breeding value for cow conception rate and, within block, assigned randomly to remain as untreated controls (CON; n = 37) or to receive an intrauterine infusion of 5.19 × 10⁸ cfu Escherichia coli and 4.34 × 10⁸ cfu Trueperella pyogenes during the luteal phase to induce endometrial inflammation (INF; n = 48). Endometrial cytology was taken on d 2 and 7 after treatment to evaluate the proportion of PMN. Rectal temperature, dry matter intake, and yields of milk and components were measured in the first 7 d after treatment. Blood serum was analyzed for concentration of haptoglobin. Leukocytes were isolated from blood on d 2 and 7 after treatment and on d 19 after artificial insemination (AI) and mRNA was quantified for a select group of genes. Cows received AI and reproduction was followed for 300 d postpartum. Bacterial infusion induced endometrial inflammation with increased proportions of PMN in the endometrial cytology on d 2 (4.4 ± 0.7 vs. 26.3 ± 2.8%) and 7 (10.9 ± 1.7 vs. 17.4 ± 2.1%) after treatment, resulting in increased mean prevalence of subclinical endometritis (>10% PMN; 23.3 ± 6.3 vs. 80.9 ± 5.1%). Rectal temperature did not differ between CON and INF, but the concentration of haptoglobin in serum tended to increase in INF compared with CON (113 ± 14 vs. 150 ± 16 µg/mL). Induced endometrial inflammation reduced yields of milk (44.9 ± 0.8 vs. 41.6 ± 0.8 kg/d), protein (1.19 ± 0.03 vs. 1.12 ± 0.03 kg/d), and lactose (2.17 ± 0.04 vs. 2.03 ± 0.04 kg/d) and tended to reduce dry matter intake (20.7 ± 0.5 vs. 19.4 ± 0.6 kg/d) in the first 7 d after treatment. Indeed, the reduction in milk yield lasted 4 wk. However, treatment did not affect yields of energy-corrected milk or fat because treatment with INF increased the concentration of fat in milk (3.54 ± 0.10 vs. 3.84 ± 0.10%). Induced endometrial inflammation reduced pregnancy per AI at all inseminations (33.4 ± 5.1 vs. 21.6 ± 3.7%) and the hazard of pregnancy (0.61; 95% CI = 0.36-1.04), which extended the median days open by 24 d. Blood leukocytes from INF cows had increased mRNA expression of the pro-inflammatory gene IL1B on d 2 and 7 after treatment, but reduced expression of the IFN-stimulated genes ISG15 and MX2 on d 19 after AI. Induced endometrial inflammation depressed production and caused long-term negative effects on reproduction in lactating dairy cows.

The impact of inflammatory stress on hypothalamic kisspeptin neurons: Mechanisms underlying inflammation-associated infertility in humans and domestic animals

Inflammatory diseases attenuate reproductive functions in humans and domestic animals. Lipopolysaccharide (LPS), an endotoxin released by bacteria, is known to disrupt female reproductive functions in various inflammatory diseases. LPS administration has been used to elucidate the impact of pathophysiological activation of the immune system on reproduction. Hypothalamic kisspeptin neurons are the master regulators of mammalian reproduction, mediating direct stimulation of hypothalamic gonadotropin-releasing hormone (GnRH) release and consequent release of gonadotropins, such as luteinizing hormone (LH) and follicle-stimulating hormone from the pituitary. The discovery of kisspeptin neurons in the mammalian hypothalamus has drastically advanced our understanding of how inflammatory stress causes reproductive dysfunction in both humans and domestic animals. Inflammation-induced ovarian dysfunction could be caused, at least partly, by aberrant GnRH and LH secretion, which is regulated by kisspeptin signaling. In this review, we focus on the effects of LPS on hypothalamic kisspeptin neurons to outline the impact of inflammatory stress on neuroendocrine regulation of mammalian reproductive systems. First, we summarize the attenuation of female reproduction by LPS during inflammation and the effects of LPS on ovarian and pituitary function. Second, we outline the inhibitory effects of LPS on pulsatile- and surge-mode GnRH/LH release. Third, we discuss the LPS-responsive hypothalamic-pituitary-adrenal axis and hypothalamic neural systems in terms of the cytokine-mediated pathway and the possible direct action of LPS via its hypothalamic receptors. This article describes the impact of LPS on hypothalamic kisspeptin neurons and the possible mechanisms underlying LPS-mediated disruption of LH pulses/surge via kisspeptin neurons.

PPARβ/δ Ligands Regulate Oxidative Status and Inflammatory Response in Inflamed Corpus Luteum-An In Vitro Study

Inflammation in the female reproductive system causes serious health problems including infertility. The aim of this study was to determine the in vitro effects of peroxisome proliferator-activated receptor-beta/delta (PPARβ/δ) ligands on the transcriptomic profile of the lipopolysaccharide (LPS)-stimulated pig corpus luteum (CL) in the mid-luteal phase of the estrous cycle using RNA-seq technology. The CL slices were incubated in the presence of LPS or in combination with LPS and the PPARβ/δ agonist-GW0724 (1 μmol/L or 10 μmol/L) or the antagonist-GSK3787 (25 μmol/L). We identified 117 differentially expressed genes after treatment with LPS; 102 and 97 differentially expressed genes after treatment, respectively, with the PPARβ/δ agonist at a concentration of 1 μmol/L or 10 μmol/L, as well as 88 after the treatment with the PPARβ/δ antagonist. In addition, biochemical analyses of oxidative status were performed (total antioxidant capacity and activity of peroxidase, catalase, superoxide dismutase, and glutathione S-transferase). This study revealed that PPARβ/δ agonists regulate genes involved in the inflammatory response in a dose-dependent manner. The results indicate that the lower dose of GW0724 showed an anti-inflammatory character, while the higher dose seems to be pro-inflammatory. We propose that GW0724 should be considered for further research to alleviate chronic inflammation (at the lower dose) or to support the natural immune response against pathogens (at the higher dose) in the inflamed corpus luteum.

Mastitis causes negative reproduction performance similar to genital diseases

The economic efficiency of dairy farms is directly influenced by reproductive performance. Reproductive performance is affected by postpartum health; however, it is unknown which diseases reduce reproductive performance or how often these diseases occur in tie-stall dairy farms. In this study, the 15 most frequent diseases in tie-stalls and their impact on reproduction were determined by logistic analysis. Data from reproductive and veterinary records of 814 cows (473 Holstein) calving between April 2016 and March 2018 reared in 9 tie-stall commercial dairy farms were used. The 15 most frequent diseases were identified by medical records. The odds ratio (OR) of the diseases reducing reproductive performance (days open, number of artificial insemination, and first artificial insemination days in milk) was measured by logistic regression analysis. We focused on mastitis, and factors (inflammation grade, causative bacteria) having a negative effect on reproduction were measured similarly. Of the 15 most frequent diseases, endometritis (OR: 5.45, p < 0.001), ovarian quiescence (OR: 3.95, p < 0.001), mastitis (OR: 2.49, p < 0.001), and follicular cyst (OR: 2.33, p = 0.006) significantly prolonged days open after adjusting for environmental factors (farm, parity, and calving season). Focusing on mastitis, mastitis with mild inflammation significantly prolonged days open. Mastitis and genital diseases were frequent diseases that reduced reproductive performance. Strategies to reduce the incidence of these diseases are considered effective for the economics of tie-stall dairy farms.

Addition of clinoptilolite in the diet reduces uterine PMN leukocytes and open days in multiparous lactating dairy cows managed in a mountain tropical pasture-based system

This study aimed to assess the effect of adding clinoptilolite in the diet on uterine health and reproductive performance in multiparous lactating dairy cows managed in a tropical pasture-based system above 2500 m of altitude. Seventy-seven multiparous Holstein crossbred cows from two farms were allocated randomly into two groups: clinoptilolite supplemented cows (CLG, n = 42) and non-supplemented cows as control (CG, n = 35). Cows from CLG were supplemented with clinoptilolite from 30 days (50 g/cow/day) before to 60 days after calving (200 g/cow/day). In CLG cows, percentages of uterine PMN leukocytes (P < 0.0001) and proportion of subclinical endometritis (P = 0.0187) were lower than in CG. The interval calving to first corpus luteum was shorter (P = 0.0759) in CLG than CG, and calving to first service interval was similar between treatments. Cows from CLG became pregnant 35 days earlier than CG cows (P = 0.0224). On farm A, calving to conception interval was 18.1 days longer in CLG than in CG (P = 0.3750); in farm B, this interval was 86.2 days shorter in CLG than in CG (P = 0.0002). In conclusion, daily addition of clinoptilolite in the diet decreased the percentage of uterine PMN leukocytes, the proportion of cows with subclinical endometritis, and shortened the calving-conception interval in multiparous lactating dairy cows.

Perspective on the relationship between reproductive tract microbiota eubiosis and dysbiosis and reproductive function

The role played by microbiota is attracting growing attention within the scientific and medical community, in both human and animal fields, in the last years. Most of the studies have been focused on the intestinal microbiome, whilst little attention has been paid to other systems, like the reproductive tract of both females and males. However, there is a growing body of information showing the interplay between reproductive tract dysbiosis, due to the action of pathogens and/or unhealthy lifestyle, and reproductive disease and disorders in many mammalian species. The present review aims to summarise current knowledge on the biodiversity of the microbiota of the reproductive tract, and the possible relationships between eubiosis or dysbiosis and reproductive health and function in both females and males.

Inhibition of lipopolysaccharide-induced suppression of luteal function in isolated perfused bovine ovaries

Recently, we observed that lipopolysaccharide (LPS) suppresses corpus luteum (CL) function in isolated perfused ovaries. It remained unclear if this suppression was due to increased luteal PGF_2α secretion or LPS-induced apoptosis. Therefore, possible impacts of PGF_2α and LPS were inhibited by a non-steroidal anti-inflammatory drug (flunixin) and an endotoxin-binding agent (polymyxin B), respectively. Bovine ovaries with a mid-cycle CL were collected immediately after slaughter and perfused for 240 min. After 50 min of equilibration, either flunixin or polymyxin B (5 μg/ml of each) were added to the perfusion medium of six ovaries, respectively. All ovaries (n = 12) were treated with E.coli LPS (0.5 μg/ml) 60 min after the onset of perfusion, and received 500 I.U. of hCG after 210 min of perfusion. Progesterone and PGF_2α were measured in the effluent perfusate every 10 and 30 min, respectively. Biopsies of the CL were collected every 60 min to determine the mRNA expression of the cytokine TNFA and factors of apoptosis (CASP3, -8). Flunixin-treatment inhibited the increase of PGF_2α after LPS-challenge that was observed in the polymyxin B-treated (PX-LPS) ovaries. After hCG-stimulation, progesterone secretion increased (P< 0.05) in group PX-LPS but not in the flunixin-treated (F-LPS) ovaries. Compared to initial values before LPS-challenge, luteal mRNA expression of TNFA and CASP3 was increased (P< 0.05) in group F-LPS at 120 and 180 min, respectively, and those of CASP8 was decreased (P< 0.05) in PX-LPS at 60 and 120 min after LPS-treatment. In conclusion, although flunixin managed to inhibit PGF_2α, it did not suffice to successfully prevent LPS-induced apoptosis. However, endotoxin-binding polymyxin B resulted in luteal responsiveness to hCG after LPS-challenge.

Effect of Foot-and-Mouth Disease Vaccination on Acute Phase Immune Response and Anovulation in Hanwoo (Bos taurus coreanae)

Vaccination against foot-and-mouth disease is the most common method for preventing the spread of the disease; the negative effects include miscarriage, early embryo death, lower milk production, and decreased growth of fattening cattle. Therefore, in this study, we analyze the side effects of vaccination by determining the acute immune response and ovulation rate after vaccinating cows for foot-and-mouth disease. The test axis was synchronized with ovulation using 100 Hanwoo (Bos taurus coreanae) cows from the Gyeongsangbuk-do Livestock Research Institute; only individuals with estrus confirmed by ovarian ultrasound were used for the test. All test axes were artificially inseminated 21 days after the previous estrus date. The control group was administered 0.9% normal saline, the negative control was injected intramuscularly with lipopolysaccharide (LPS; 0.5 µg/kg), and the test group was administered a foot-and-mouth disease virus vaccine (FMDV vaccine; bioaftogen, O and A serotypes, inactivated vaccine) 2, 9, and 16 days before artificial insemination. White blood cells and neutrophils increased significantly 1 day after vaccination, and body temperature in the rumen increased for 16 h after vaccination. Ovulation was detected 1 day after artificial fertilization by ovarian ultrasound. The ovulation rates were as follows: control 89%, LPS 60%, FMDV vaccine (-2 d) 50%, FMDV vaccine (-9 d) 75%, and FMDV vaccine (-16 d) 75%. In particular, the FMDV vaccine (-2 d) test group confirmed that ovulation was delayed for 4 days after artificial insemination. In addition, it was confirmed that it took 9 days after inoculation for the plasma contents of haptoglobin and serum amyloid A to recover to the normal range as the main acute immune response factors. The conception rate of the FMDV vaccine (-2 d) group was 20%, which was significantly lower than that of the other test groups.

Inflammatory diseases in dairy cows: Risk factors and associations with pregnancy after embryo transfer

The objectives of the present prospective cohort study were to identify risk factors for inflammatory diseases in Holstein-Gyr crossbred dairy cows and characterize the associations of those diseases with pregnancy per embryo transfer (ET). Diseases were diagnosed in the first 60 d postpartum in 252 primiparous and 481 multiparous cows. Uterine diseases (UTD) included retained placenta, metritis, clinical endometritis, and subclinical endometritis. Nonuterine diseases (NUTD) included mastitis, lameness, pneumonia, and displaced abomasum. Blood was sampled on d 0, 1, and 2 postpartum and analyzed for concentrations of haptoglobin, fatty acids, total Ca (tCa), P, and Mg, and again on d 8 postpartum and analyzed for concentration of β-hydroxybutyrate. The association between concentrations of metabolites in serum and inflammatory diseases was determined. Cows received a timed ET program starting 28 ± 3 d postpartum with first ET at 46 ± 3 d postpartum using fresh in vitro-produced embryos. Pregnancy was diagnosed on d 31 and 59 of presumptive gestation. Overall, 63.3% of the cows were diagnosed with UTD and 20.6% with NUTD. The risk factors for UTD included season of calving, parity group, calving problems, days with subclinical hypocalcemia, and serum concentrations of haptoglobin and Mg, whereas the risk factors for NUTD were parity group and serum Mg concentration. Cows that developed UTD had increased concentrations of haptoglobin on d 2 and fatty acids on d 1 and 2, and reduced concentrations of tCa on d 1 and 2 and of P and Mg on d 2 postpartum compared with cows without UTD. Cows that developed NUTD had increased concentrations of fatty acids on d 0 to 2 postpartum, and decreased concentrations of tCa and P on d 0 and 1, and of Mg on d 1 and 2 postpartum compared with cows without NUTD. Cows that developed NUTD had a 340-kg reduction in milk yield in the first 60 d postpartum. Inflammatory diseases were associated with lesser body condition score and increased loss of body condition in the first 70 d postpartum. Maintenance of pregnancy after ET was reduced in UTD cows following the first (41.7 vs. 25.4%) or all ET (46.4 vs. 36.2%), whereas maintenance of pregnancy was reduced in NUTD cows only at the second ET (39.0 vs 25.9%). The reduced pregnancy maintenance in UTD cows combined with a reduced 21-d service rate (61.9 vs. 54.8%) decreased the 21-d cycle pregnancy rate (28.6 vs. 19.9%) and the hazard of pregnancy to 300 d postpartum by 35%, resulting in an extra 32 d open. In conclusion, inflammatory diseases depressed fertility in dairy cows receiving ET, with the greatest impact observed in UTD cows. This suggests that local inflammation of the uterus impairs maintenance of pregnancy in dairy cows following ET.

Effects of clinical mastitis and puerperal diseases on reproductive efficiency of dairy cows

The objective of this study was to evaluate the effects of clinical mastitis (CM) occurring before or after the first AI postpartum, and puerperal diseases (PD) on the pregnancy per artificial insemination (P/AI), number of AI/conception, and days open (DO) of two different dairy herds (Girolando and Holstein). The CM, PD (retained placenta and metritis), and reproductive data were collected from two dairy farms throughout 1 year. Both farms were located in the southern region of Minas Gerais State, Brazil. One herd was composed of Girolando cows and the other of Holstein cows. Cows were inseminated after estrus detection or submitted to timed AI. Only CM cases (clots in milk accompanied or not by udder inflammation) that occurred before or after first AI postpartum (from calving until 35 days after the first AI) were considered. There were no effects of CM, PD, or both diseases on the reproductive efficiency of the Girolando herd. In the Holstein herd, a reduce P/AI and prolonged DO were verified for those affected by ≥ 2 CM cases. Holstein cows with CM also required more inseminations to become pregnant. A decrease in the P/AI and an increase in the number of AI/conception and DO were observed in cows of the Holstein herd that developed only CM, only PD, and for those diagnosed with both diseases. In summary, considering that some management differences exist between the two dairy farms, CM occurrence (before or after the first AI postpartum) and puerperal diseases negatively affected the reproductive efficiency of the Holstein herd. However, these diseases did not compromise the reproductive efficiency of the Girolando herd.

Intrauterine therapy with ozone reduces subclinical endometritis and improves reproductive performance in postpartum dairy cows managed in pasture-based systems

New postpartum strategies have been developed in dairy cows to ameliorate uterine health and reproductive performance, especially the first service conception rates. This study aimed to assess the effect of intrauterine therapy with ozone (IUTO) in early postpartum on subclinical endometritis prevalence and reproductive parameters in dairy cows under commercial farm conditions. For this purpose, eighty clinically healthy cows with a body condition score between 3.0 and 3.5, from four dairy farms, were randomly allocated into two groups: ozone therapy group (OG, n = 40), which were subjected to IUTO, and control group (CG, n = 40). Content of uterine polymorphonuclear (PMN) leukocytes and subclinical endometritis (SE) percentage were assessed at 35 days after calving by uterine cytology. A second cytology was performed 72 h after IUTO. Reproductive parameters such as interval calving to first service (IFS), number of services per conception (nSC), interval calving to conception (ICC) and first service conception rate (FSCR) were analysed. The second endometrial cytology demonstrated that IUTO reduced (P < 0.01) both PMN (3.7 ± 1.4 vs. 7.6 ± 1.1%) and SE (5.0 vs. 50.0%) percentages compared with CG. Likewise, after ozone treatment, both nSC (2.1 ± 0.3 vs. 3.1 ± 0.2; P < 0.01) and ICC (126.2 ± 9.7 vs. 149.0 ± 9.0; P = 0.0672) decreased, and FSCR increased (50.0 vs. 16.2%; P < 0.01) compared with CG. In conclusion, intrauterine ozone therapy applied at 35 days after calving reduced subclinical endometritis prevalence and improved reproductive performance in postpartum dairy cows managed in a pasture-based system.

Intrafollicular lipopolysaccharide injection delays ovulation in cows

The aim of this study was to evaluate effects of intra-follicular (i.f.) treatment with lipopolysaccharide (LPS) on follicular and luteal development in cows. There were 18 non-lactating cows assigned to two groups to address this aim: control group (n = 9), which received an i.f. injection of saline; and LPS group (n = 9), which received an i.f. injection of 1 μg of LPS per mL of follicular fluid. Cows were treated with an intravaginal P4 releasing device (IVD) and estradiol benzoate on D0. On D4 and D5 cows were treated with cloprostenol sodium and on D7 the IVD was removed. At 12 h after IVD removal, cows were administered the i.f. injection of LPS or saline. After administration of these treatments, follicular development was evaluated every 12 h until ovulation. The LPS treatment increased blood flow in pre-ovulatory follicles (P = 0.05). Follicle growth was reduced by LPS injection (P < 0.02) resulting a longer period to the time of ovulation for cows in the LPS than control group (P = 0.03). The percentage of cows having ovulations was less for the LPS than control group (P = 0.03). The diameter of the CL, CL blood flow and P4 concentrations 5 and 12 days after ovulation did not differ between groups (P> 0.05). In conclusion, intra-follicular treatment with LPS resulted in a decreased rate of follicle growth, delayed timing of ovulations and a lesser number of cows having ovulations.

Oocyte maturation in plasma or follicular fluid obtained from lipopolysaccharide-treated cows disrupts its developmental competence

Mastitis has deleterious effects on ovarian function and reproductive performance. We studied the association between plasma or follicular fluid (FF) obtained from endotoxin-induced mastitic cows, and oocyte developmental competence. Lactating Holstein cows were synchronized using the Ovsynch protocol. On Day 6 of the synchronized cycle, an additional PGF_2α dose was administered, and either Escherichia coli endotoxin (LPS, 10 μg; n = 3 cows) or saline (n = 3 cows) was administered to one udder quarter per cow, 36 h later. Milk samples were collected and rectal temperatures recorded. Cows treated with LPS showed a typical transient increase in body temperature (40.3 °C ± 0.4), whereas cows treated with saline maintained normal body temperature (38.9 °C ± 0.04). A higher (P < 0.05) somatic cell count was recorded for cows treated with LPS. Plasma samples were collected and FF was aspirated from the preovulatory follicles by transvaginal ultrasound probe, 6 h after LPS administration. Radioimmunoassay was performed on plasma samples to determine estradiol and cortisol concentrations. Either FF or plasma was further used as maturation medium. In the first experiment, oocytes were matured in TCM-199 (Control) or in FF aspirated from cows treated with saline (FF-Saline) or LPS (FF-LPS). Cleavage rate to the 2- to 4-cell stage embryo did not differ among groups. However, the proportion of developed blastocysts on Day 7 postfertilization in the FF-LPS group tended to be lower for that in FF-Saline and was lower (P < 0.05) than that in the Control groups (10.6 vs. 22.4 and 24.4%, respectively). In the second experiment, oocytes were matured in TCM-199 (Control), or in plasma obtained from cows treated with saline (Plasma-Saline) or LPS (Plasma-LPS). Similar to the FF findings, cleavage rate did not differ among groups; however, the proportion of developing blastocysts tended to be lower in the Plasma-LPS group than in the Plasma-Saline group and was lower (P < 0.05) from that in the Control group (11.0 vs. 25.5 and 34.7%, respectively). The proportion of apoptotic cells per blastocyst, determined by TUNEL assay, did not differ among the experimental groups. The findings shed light on the mechanism by which mastitis induces a disruption in oocyte developmental competence. Further studies are required to clarify whether the negative effect on oocyte developmental competence is a result of LPS, by itself, or due to elevation of secondary inflammatory agents.

Response of lactating dairy cows fed different supplemental zinc sources with and without evaporative cooling to intramammary lipopolysaccharide infusion: intake, milk yield and composition, and hematologic profile1

The objective of this study was to determine the effect of dietary supplemental Zn source and evaporative cooling on intake, milk yield and composition, and the rate of leukocyte migration into the mammary gland following intramammary lipopolysaccharide (LPS) infusion. Multiparous Holstein cows (n = 72) were assigned to one of four treatments with a 2×2 factorial arrangement including two sources of supplemental Zn: 75 mg/kg Zn hydroxychloride or 35 mg/kg Zn hydroxychloride + 40 mg/kg Zn-Met complex (ZMC) each with or without evaporative cooling. The cooling system was implemented by the use of fans and misters over the freestall and feeding areas. On day 34 of the experiment, cows (n = 16; days in milk = 263 ± 63 d) received an infusion of 10 μg of LPS, or a saline control, in the left or right rear quarters. Individual milk samples from both quarters were collected at -12, -4, 0, 6, 12, 24, 48, 72, 96, 120, 144, and 168 h relative to infusion and analyzed for composition and bovine serum albumin. Rectal temperature and respiration rate were assessed and blood samples were collected at the same time points (with an additional sample at 3 h) for analyses of lactose and cortisol. Complete blood counts were performed on samples collected within the first 24 h post infusion. Intramammary LPS infusion reduced (P < 0.01) milk yield, DMI and feed efficiency regardless of dietary or cooling treatments. Non-cooled cows tended (P = 0.09) to have greater feed efficiency (=milk yield/DMI) at 1 d after infusion than those subjected to cooling. Intramammary LPS infusion dramatically increased (P < 0.01) milk somatic cell count (SCC) but treatments had no apparent impact on milk SCC. Compared with cooled cows, non-cooled cows had greater (P < 0.05) plasma lactose concentrations, but lower (P < 0.03) blood concentrations of neutrophils and lymphocytes at 3 h post infusion. This suggests a greater leukocyte migration into the mammary gland of heat-stressed cows. In conclusion, noncooled cows tended to maintain greater feed efficiency and appeared to have greater leukocyte migration into the mammary gland immediately after intramammary LPS infusion compared with cooled cows. Dietary supplemental Zn source had no impact on measures assessed after intramammary LPS infusion.

Impacts of chronic and increasing lipopolysaccharide exposure on production and reproductive parameters in lactating Holstein dairy cows

Lipopolysaccharide (LPS) administration causes immunoactivation, which negatively affects production and fertility, but experimental exposure via an acute bolus is unlikely to resemble natural infections. Thus, the objectives were to characterize effects of chronic endotoxemia on production parameters and follicular development in estrous-synchronized lactating cows. Eleven Holstein cows (169 ± 20 d in milk; 681 ± 16 kg of body weight) were acclimated to their environmental surroundings for 3 d and then enrolled in 2 experimental periods (P). During P1 (3 d) cows consumed feed ad libitum and baseline samples were obtained. During P2 (7 d), cows were assigned to continuous infusion of either (1) saline-infused and pair-fed (CON-PF; 40 mL/h of saline i.v.; n = 5) or (2) LPS infused and ad libitum fed (LPS-AL; Escherichia coli O55:B5; 0.017, 0.020, 0.026, 0.036, 0.055, 0.088, and 0.148 μg/kg of body weight/h i.v. on d 1 to 7, respectively; n = 6). Controls were pair-fed to the LPS-AL group to eliminate confounding effects of dissimilar nutrient intake. Infusing LPS temporally caused mild hyperthermia on d 1 to 3 (+0.49°C) relative to baseline. Dry matter intake of LPS-AL cows decreased (28%) on d 1 of P2, then progressively returned to baseline. Relative to baseline, milk yield from LPS-AL cows was decreased on d 1 of P2 (12%). No treatment differences were observed in milk yield during P2. Follicular growth, dominant follicle size, serum progesterone (P4), and follicular P4 and 17β-estradiol concentrations were similar between treatments. Serum 17β-estradiol tended to increase (115%) and serum amyloid A and LPS-binding protein were increased (118 and 40%, respectively) in LPS-AL relative to CON-PF cows. Compared with CON-PF, neutrophils in LPS-AL cows were initially increased (45%), then gradually decreased. In contrast, monocytes were initially decreased (40%) and progressively increased with time in the LPS-AL cows. Hepatic mRNA abundance of cytochrome P450 family 2 subfamily C (CYP2C) or CYP3A was not affected by LPS, nor was there a treatment effect on toll-like receptor 4 or LBP; however, acyloxyacyl hydrolase and RELA subunit of nuclear factor kappa B tended to be increased in LPS-AL cows. These data suggest lactating dairy cows become tolerant to chronic and exponentially increasing LPS infusion in terms of production and reproductive parameters.

Effect of repeated intravenous lipopolysaccharide infusions on systemic inflammatory response and endometrium gene expression in Holstein heifers

This study aimed to evaluate the effect of repeated intravenous lipopolysaccharide (LPS) infusions in nonlactating heifers on (1) the systemic proinflammatory state as measured by biomarkers in blood and plasma, and (2) endometrial gene expression of candidate transcripts on d 15 of gestation. Our hypothesis was that target transcripts related to a major functional group would be negatively modified in the preimplantation endometrium by the LPS treatments. In the first experiment (n = 13), a systemic proinflammatory state [defined as increased plasma concentrations of tumor necrosis factor (TNF)-α and haptoglobin for 2 wk] was established using 2 different sequential LPS infusion protocols. In the second experiment, heifers (n = 22; 11 mo of age) had their time of ovulation synchronized by a modified Ovsynch protocol and were enrolled in 1 of 2 treatments: control (CON; n = 11), which received sterile saline solution i.v., and LPS treatment (LPS; n = 11), submitted to repeated i.v. LPS injections (0.10, 0.25, 0.50, 0.75, 1.00, and 1.25 µg/kg) starting 2 d after artificial insemination (AI; d 0) and then every other day until d 15 after AI. At each LPS injection, rectal temperatures were measured hourly for 6 h. Blood samples were collected from d -1 to d 13 for analyses of progesterone, TNF-α, and haptoglobin in plasma, along with white blood cell (WBC) count and differential analysis. On d 15, endometrium tissue biopsies were taken and kept at -80°C until quantitative real-time PCR analysis of 30 target transcripts related to the immune system, adhesion molecules, and endometrium receptivity. Data were checked for normality and analyzed by repeated-measures ANOVA using PROC UNIVARIATE and PROC MIXED of SAS (SAS Institute Inc., Cary, NC). After each LPS injection, temperature was greater in the first 4 h in the LPS group compared with CON. Both TNF-α and haptoglobin increased in the LPS treatment with a significant treatment by day interaction. Total leukocyte count did not differ between treatments, but the differential count increased for neutrophils, band cells, and monocytes, and decreased for lymphocytes and eosinophils in LPS compared with CON. Progesterone concentrations in plasma did not differ between treatments during the experimental period. Out of 30 target genes analyzed, 3 transcripts were differentially expressed: indoleamine 2,3-dioxygenase (IDO; fold-change = 0.48) and pentraxin-3 (PTX3; fold-change = 0.38) were downregulated, whereas myxovirus-resistance protein (MX1; fold-change = 2.85) was upregulated in the LPS group. Sequential LPS injections were able to induce a prolonged systemic proinflammatory state, but effects on gene expression were limited to transcripts associated with the immune system. These results suggest that a mechanism for subfertility is linked to a proinflammatory state in dairy heifers.

Polymorphisms in the anti-oxidant paraoxonase-1 (PON1) gene associated with fertility of postpartum dairy cows

Paraoxonase 1 (PON1) is a negative acute phase plasma protein synthesized by the liver that has anti-oxidant activity. The aim of this study was to evaluate the association of single nucleotide polymorphisms (SNPs) in the PON1 promoter region with plasma PON1 activity and fertility in Holstein dairy cows. Sixty-eighty Holstein cows were used in this initial investigative study. Blood samples were collected weekly beginning 28 days prior to expected calving, twice weekly in week 1 and 2 postpartum, and then once weekly through 6 weeks postpartum for plasma PON1 activity analysis. Cows were synchronized for ovulation and timed AI at 63-70 DIM using an Ovsynch program. Pregnancy diagnosis was confirmed by rectal palpation and reproductive performance data was recorded until 210 DIM. DNA was extracted from blood of each cow and a fragment of proximal PON1 gene promoter was sequenced. Seven single nucleotide polymorphisms (SNPs) were identified in the promoter region of the PON1 gene at positions -22, -105, -176, -221, -392, -611 and -676, six of which were significantly associated with plasma PON1 activity level. The SNPs -221 and -392 were significantly associated with both plasma PON1 activity and the calving to conception interval (P < 0.05) with no significant effect on calving to first ovulation interval. In conclusion, the genotypes associated with higher plasma PON1 activity in SNP locations -221 and -392 were also associated with a reduced calving to conception interval in this study set of cows. These SNPs may provide novel genetic markers for improved fertility in future larger studies in dairy cows.

Tolerance and Innate Immunity Shape the Development of Postpartum Uterine Disease and the Impact of Endometritis in Dairy Cattle

Bacteria are ubiquitous in the bovine uterus after parturition, but 50 years ago, cows tolerated these bacteria and few animals developed uterine disease. Now, up to 40% of dairy cattle develop postpartum uterine disease. Uterine disease causes infertility by compromising the function of not only the endometrium but also the ovary. Animals defend themselves against pathogens using tolerance and resistance mechanisms. Tolerance is the ability to limit the disease severity induced by a given pathogen burden. Resistance is the ability to limit the pathogen burden and is usually the function of immunity. Endometrial cells contribute to tolerance and have roles in innate immunity and the inflammatory response to pathogens. However, failures in endometrial tolerance and the character of the inflammatory response shape postpartum uterine disease. We propose that uterine health is more dependent on the ability of the endometrium to tolerate pathogens than the ability to resist invading bacteria.

Subclinical mastitis interferes with ovulation, oocyte and granulosa cell quality in dairy cows

The objective was to evaluate the effect of mastitis by somatic cell count (SCC) on follicular growth, ovulation, oocytes and cumulus cells quality and on the concentration and size of exosomes in follicular fluid of dairy cows. In the study, crossbred cows (Bos taurus - Holstein x Bos indicus - Gir) were classified for analysis as Control (SCC<200.000 cells/mL) and Mastitis (SCC>400.000 cells/mL) groups. In experiment 1 (follicular dynamics), cows (n = 57) were submitted to ultrasound evaluations every 24 h, from progesterone-releasing-intravaginal-device (PRID) removal (D8) until 48 h later (D10). Thereafter, evaluations were performed every 12 h, until ovulation or up to 96 h after PRID removal. In experiment 2 (oocyte, cumulus complexes, and follicular fluid evaluation), cows (n = 26) were submitted to follicular aspiration (OPU) for oocyte quality and cumulus cells transcript evaluation. The amount of cumulus complexes transcripts (BCL2, BAX, PI3K, PTEN, FOXO3) was determined by Real-Time Polymerase Chain Reaction. Moreover, seven days after the OPU session, the dominant follicle was aspirated. Exosomes were isolated from the follicular fluid for evaluation of particle size and concentration. Ovulation rate [Control 77.4% (24/31) and Mastitis 57.7% (15/26); P = 0.09] and viable oocytes rate [Control 59.1% (130/220) and Mastitis 41.9% (125/298); P = 0.01] were higher in Control animals. Additionally, there was a greater number of degenerate oocytes [Control 6.7 ± 1.2 and Mastitis 13.3 ± 5.5; (P = 0.001)] in subclinical mastitis cows. There was greater abundance (P = 0.003) of BAX cumulus cell transcripts and exosome mean (P = 0.03) and mode (P = 0.02) was smaller in subclinical mastitis cows. In conclusion, ovulation rate, oocyte quality, and exosome diameter were smaller in cows with SCC>400.000 cells/mL.

Disruption of female reproductive function by endotoxins

Endotoxemia can be caused by obesity, environmental chemical exposure, abiotic stressors and bacterial infection. Circumstances that deleteriously impact intestinal barrier integrity can induce endotoxemia, and controlled experiments have identified negative impacts of lipopolysaccharide (LPS; an endotoxin mimetic) on folliculogenesis, puberty onset, estrus behavior, ovulation, meiotic competence, luteal function and ovarian steroidogenesis. In addition, neonatal LPS exposures have transgenerational female reproductive impacts, raising concern about early life contacts to this endogenous reproductive toxicant. Aims of this review are to identify physiological stressors causing endotoxemia, to highlight potential mechanism(s) by which LPS compromises female reproduction and identify knowledge gaps regarding how acute and/or metabolic endotoxemia influence(s) female reproduction.

Human granulosa-luteal cells initiate an innate immune response to pathogen-associated molecules

The microenvironment of the ovarian follicle is key to the developmental success of the oocyte. Minor changes within the follicular microenvironment can significantly disrupt oocyte development, compromising the formation of competent embryos and reducing fertility. Previously described as a sterile environment, the ovarian follicle of women has been shown to contain colonizing bacterial strains, whereas in domestic species, pathogen-associated molecules are concentrated in the follicular fluid of animals with uterine infection. The aim of this study is to determine whether human granulosa-luteal cells mount an innate immune response to pathogen-associated molecules, potentially disrupting the microenvironment of the ovarian follicle. Human granulosa-luteal cells were collected from patients undergoing assisted reproduction. Cells were cultured in the presence of pathogen-associated molecules (LPS, FSL-1 and Pam3CSK4) for 24h. Supernatants and total RNA were collected for assessment by PCR and ELISA. Granulosa-luteal cells were shown to express the molecular machinery required to respond to a range of pathogen-associated molecules. Expression of TLR4 varied up to 15-fold between individual patients. Granulosa-luteal cells increased the expression of the inflammatory mediators IL1B, IL6 and CXCL8 in the presence of the TLR4 agonist E. coli LPS. Similarly, the TLR2/6 ligand, FSL-1, increased the expression of IL6 and CXCL8. Although no detectable changes in CYP19A1 or STAR expression were observed in granulosa-luteal cells following challenge, a significant reduction in progesterone secretion was measured after treatment with FSL-1. These findings demonstrate the ability of human granulosa-luteal cells to respond to pathogen-associated molecules and generate an innate immune response.

Mastitis outcomes on pre-ovulatory follicle diameter, estradiol concentrations, subsequent luteal profiles and conception rate in Buffaloes

The objectives of this study was to investigate the outcome of mastitis, in its clinical or subclinical forms, on the mean diameter of pre-ovulatory follicle (POF), plasma estradiol concentration on the day of estrus, subsequent luteal profile and subsequent conception rate in buffaloes. Sixty dairy buffalo (Bubalus bubalus) conducted in this study were divided into three groups {healthy (H), n=20; subclinical mastitis (SCM), n=18; and clinical mastitis (CM), n=22}. Ultrasonography of ovaries revealed that mean diameter of POF was larger (P<0.05) in H buffalo (14.35mm) compared to SCM (12.40mm) and CM (10.25mm). Also, plasma estradiol concentration on the day of estrus was higher (P<0.05) in H buffalo compared to SCM and CM counterparts; 34.95 vs. 32.87 and 27.50pg/ml, respectively. Besides, positive correlation was observed between the POF diameter with plasma estradiol concentration in H, SCM and CM buffaloes (r=0.64, 0.74, 0.72 respectively, P<0.05). Moreover, positive correlations (P<0.01) were found on days 9, 12, 16, and 21 post-ovulation between POF diameter and luteal profile. Thus, the conception rate in H buffalo was higher (P<0.05) compared with SCM and CM counterparts; 55% vs. 38.89 and 18.18%, respectively. In conclusion, mastitis in its clinical or subclinical forms disrupts the functioning of the pre-ovulatory follicle on the day of estrus, associated with low follicular estradiol production, resulting in suppression to subsequent luteal profile leading to substantial decrease in pregnancy consequence of buffaloes.

The acute effect of intravenous lipopolysaccharide injection on serum and intrafollicular HDL components and gene expression in granulosa cells of the bovine dominant follicle

The aim of this study was to evaluate the effect of an acute systemic inflammatory response induced by lipopolysaccharide (LPS) in the serum and follicular fluid (FF) high-density lipoprotein (HDL) components, hormone concentrations and granulosa cell gene expression. For this purpose, twenty non-lactating Jersey dairy cows were submitted to a progesterone (P4) - estradiol (E2) based synchronization protocol. Cows received a single i.v. dose of LPS (2.5 μg/kg of body weight) or saline solution (CTL Group) 2 h after P4 insert removal. Blood, granulosa cells and FF samples were collected six hours after LPS injection. Five hours after LPS injection rectal temperature was increased in LPS (P < 0.0001, 40.4 ± 0.1 °C) compared to the CTL cows (38.8 ± 0.1 °C). Serum PON1 activity was reduced by LPS injection (130.2 ± 5.1 vs. 99.6 ± 3.3 U/mL; P < 0.001), as well as HDL-cholesterol concentrations (70.3 ± 5.3 vs. 50.1 ± 6.2 mg/dL; P < 0.05). The FF E2 and P4 concentrations were not different between groups (P > 0.05). The PON1 activity in the FF was also decreased by LPS injection (P = 0.01). In comparison to CTL group, cows injected with LPS had a ten fold reduction in STAR, TLR4 and TNF mRNA expression (P < 0.05). In conclusion, an intravenous LPS challenge in cows induced an acute systemic inflammatory response reducing HDL and its components in serum but not in the FF. Only PON1 activity serum reduction was reflected in the FF in the short term. Additionally, steroidogenic and inflammatory genes had reduced expression in the granulosa cells.

Comparing the effects of heat stress and mastitis on ovarian function in lactating cows: basic and applied aspects

Reduced reproductive performance of lactating cows is strongly associated with environmental and pathogenic stressors. This review summarizes the most recent knowledge on the effects of acute or chronic heat stress (HS) and acute or chronic intramammary infection (IMI) on ovarian function. It also offers various approaches for improving the fertility of cows under chronic HS or IMI. Comparing the 2 stressors reveals a few similarities in the mode of alteration in the hypothalamus-pituitary-ovarian axis, in particular, in the follicle and its enclosed oocyte. Both HS and IMI cause a reduction in the preovulatory LH surge, with a pronounced effect in cows with IMI, and consequently, ovulation is being delayed or inhibited. Both stresses induce changes in follicular growth dynamics, reduce follicular steroidogenesis, and disrupt follicular dominance. Unlike their effects on follicular function, the effects of mastitis and HS on corpus luteum (CL) function are debatable. Under chronic summer thermal stress, several, but not all, studies show reduced progesterone secretion by the CL. Subclinical mastitis does not affect CL function, whereas the effect of clinical mastitis is controversial; some show a reduction in progesterone, whereas others do not. Both stresses have been found to impair cytoplasmic and nuclear maturation of oocytes, associated with reduced embryonic development. These findings have provided insights into the mechanism by which HS and IMI compromise fertility, which enable developing new strategies to mitigate these effects. For instance, treatment with GnRH and PGF2α to induce follicular turnover successfully improved conception rate in subpopulations of HS cows during the summer, in particular, primiparous cows and cows with high BCS. The "Ovsynch" program, also based on the use of GnRH and PGF2α, has been shown to improve conception rate of subclinical mastitic cows, most likely due to better synchronization of timing of ovulation with that of AI. Supplementing progesterone after AI improves conception rate of HS cows, particularly those with postpartum uterine disease and low BCS. It should be noted that similarities between the 2 stressors do not necessarily suggest a shared mechanism. Although not clear enough, an additive deleterious effects of HS and IMI on reproduction is suggested.

PHYSIOLOGY AND ENDOCRINOLOGY SYMPOSIUM: Uterine infection: linking infection and innate immunity with infertility in the high-producing dairy cow

Uterine contamination with bacteria is ubiquitous in the postpartum dairy cow. Nearly one-half of all postpartum dairy cows develop clinical disease resulting in metritis and endometritis, which cause depressed milk production and infertility. The causative links between uterine infection and infertility include a hostile uterine environment, disrupted endocrine signaling, and perturbations in ovarian function and oocyte development. In this review we consider the various mechanisms linking uterine infection with infertility in the dairy cow, specifically 1) innate immune signaling in the endometrium, 2) alteration in endocrine signaling in response to infectious agents, and 3) impacts of infection on ovarian function, oocyte development, and follicular development. Normal ovarian follicular and oocyte development requires a series of temporally and spatially orchestrated events; however, several of the cellular pathways required for ovarian function are also used during the innate immune response to bacterial pathogens. We propose that activation of cellular pathways during this immune response has a negative impact on ovarian physiology, which is manifest as infertility detected after the clearance of the bacteria. This review highlights how new insights into infection and immunity in cattle are linked to infertility.

LPS-mediated effects and spatio-temporal expression of TLR2 and TLR4 in the bovine corpus luteum

When given intravenously (iv), lipopolysaccharide (LPS) transiently suppresses the structure and function of the bovine corpus luteum (CL). This is associated with increased release of prostaglandin (PG) F2α metabolite. The underlying regulatory mechanisms of this process remain, however, obscure. Therefore, the aims of this study were: i) to investigate the expression of the LPS receptor toll-like receptor 4 (TLR4) and 2 (TLR2) in the bovine CL during early, mid- and late luteal phases; and ii) to further dissect the mechanisms of LPS-mediated suppression of luteal function. As revealed by semi-quantitative qPCR and immunohistochemistry, both receptors were detectable throughout the luteal lifespan. Their mRNA levels increased from the early toward the mid-luteal phase; no further changes were observed thereafter. The TLR4 protein seemed more highly represented than TLR2. The cellular localization of TLRs was in blood vessels; weaker signals were observed in luteal cells. Additionally, cows were treated either with LPS (iv, 0.5 μg/kg BW) or with saline on Day 10 after ovulation. Samples were collected 1200 h after treatment and on Day 10 of the respective subsequent (untreated) cycle. The mRNA expression of several possible regulatory factors was investigated, revealing the suppression of PGF2α receptor (PTGFR), STAR protein and 3β-hydroxysteroid dehydrogenase, compared with controls and subsequent cycles. The expression of TLR2 and TLR4, interleukin 1α (IL1A) and 1β (IL1B) and of PGF2α and PGE2 synthases (HSD20A and mPTGES respectively) was increased. The results demonstrate the presence of TLR2 and TLR4 in the bovine CL, and implicate their possible involvement in the deleterious effects of LPS on its function.

Lipopolysaccharide enhances apoptosis of corpus luteum in isolated perfused bovine ovaries in vitro

Lipopolysaccharide (LPS), the endotoxin of Gram-negative bacteria, has detrimental effects on the structure and function of bovine corpus luteum (CL)in vivo. The objective was to investigate whether these effects were mediated directly by LPS orviaLPS-induced release of PGF2α. Bovine ovaries with a mid-cycle CL were collected immediately after slaughter and isolated perfused for 240 min. After 60 min of equilibration, LPS (0.5 μg/ml) was added to the medium of five ovaries, whereas an additional six ovaries were not treated with LPS (control). After 210 min of perfusion, all ovaries were treated with 500 iu of hCG. In the effluent perfusate, concentrations of progesterone (P4) and PGF2αwere measured every 10 and 30 min, respectively. Punch biopsies of the CL were collected every 60 min and used for RT-qPCR to evaluate mRNA expression of receptors for LPS (TLR2,-4) and LH (LHCGR); the cytokineTNFA; steroidogenic (STAR,HSD3B), angiogenic (VEGFA121,FGF2), and vasoactive (EDN1) factors; and factors of prostaglandin synthesis (PGES,PGFS,PTGFR) and apoptosis (CASP3,-8,-9). Treatment with LPS abolished the hCG-induced increase in P4(P≤0.05); however, there was a tendency (P=0.10) for increased release of PGF2αat 70 min after LPS challenge. Furthermore, mRNA abundance ofTLR2,TNFA,CASP3,CASP8,PGES,PGFS, andVEGFA121increased (P≤0.05) after LPS treatment, whereas all other factors remained unchanged (P>0.05). In conclusion, reduced P4responsiveness to hCG in LPS-treated ovariesin vitrowas not due to reduced steroidogenesis, but was attributed to enhanced apoptosis. However, an impact of luteal PGF2αcould not be excluded.

Reduced use of glucose by normoxic cow's mammary gland under acute inflammation: an example of homeostatic aerobic glycolysis

The concentration of glucose and glucose-derived carbons in milk reflect their concentrations in the mammary epithelial cell cytosol.

Relationship of concentrations of cortisol in hair with health, biomarkers in blood, and reproductive status in dairy cows

Hair cortisol has been used to measure chronic stress in dairy cows as it offers the advantage of being noninvasive, fast, and able to indicate levels of cortisol over long periods. The aim of this study was to determine the associations between hair cortisol with clinical disorders, reproductive status, and the development of subclinical endometritis in dairy cows. Furthermore, we aimed to determine the association between hair cortisol concentrations and blood markers associated with metabolic status and acute inflammation. In experiment 1, cows (n=64) were hair sampled every 3wk from the tail switch beginning at calving (d 0) until d 126 for cortisol analysis; blood samples were collected every 3wk from d 0 until 42 for β-hydroxybutyrate and glucose analysis. In experiment 2, cows (n=54) were chosen retrospectively by diagnosis of subclinical endometritis (END), subclinical endometritis and at least 1 clinical disease (END+CLIN), or as healthy (control) using a cytobrush and ultrasonography at 30±3d in milk. At the same time, animals were hair sampled for cortisol analysis and blood sampled for haptoglobin and ceruloplasmin analysis. Health records were recorded throughout both experimental periods. Animals with clinical disease presented higher cortisol concentrations than clinically healthy animals in experiment 1 [geometric mean (95% confidence interval); 8.8 (7.8, 9.9) vs. 10.7 (9.6, 12.0) pg/mg]; however, animals diagnosed with subclinical endometritis in experiment 2 did not differ in hair cortisol concentrations [11.7 (9.8, 14.0), 12.2 (9.3, 15.9), 10.5 (8.1, 13.6) pg/mg for control, END, and END+CLIN, respectively]. In experiment 1, an effect of sample day was noted, where d 21 had higher cortisol concentrations than d 42, 84, and 126, but not from d 0 for both parities. Within both experiments, a parity effect was present where multiparous animals consistently had higher cortisol concentrations than primiparous animals. Multiparous cows that became pregnant by 100d postpartum had lower concentrations of hair cortisol at d 42 and 84 in milk. Lastly, other biomarkers associated with metabolic status and acute inflammation, such as glucose, β-hydroxybutyrate, haptoglobin, and ceruloplasmin, were not strongly correlated with measurements of cortisol in hair. Overall, hair cortisol measurements appear to be associated with clinical disorders and have a direct association with pregnancy status; however, concentrations of hair cortisol may not be suited to differentiate situations of stress with lower magnitudes, such as the development of subclinical disease.

Subclinical mastitis disrupts oocyte cytoplasmic maturation in association with reduced developmental competence and impaired gene expression in preimplantation bovine embryos

Subclinical chronic mastitis was induced to examine the effects on oocyte developmental competence. Uninfected Holstein cows were intramammary administrated with serial (every 48h for 20 days) low doses of toxin of Staphylococcus aureus origin (Gram-positive; G+), endotoxin of Escherichia coli origin (Gram-negative; G-) or sterile saline (control). Follicular fluid of toxin- and saline-treated cows was aspirated from preovulatory follicles and used as maturation medium. Oocytes harvested from ovaries collected at the abattoir were matured and then fertilised and cultured for 8 days. The percentage of oocytes undergoing nuclear maturation, determined by meiotic nuclear stages, did not differ between groups. Cytoplasmic maturation, determined by cortical granule distribution, was affected by both toxins (PPPPTGS2) mRNA increased, whereas that of growth differentiation factor 9 (GDF9) decreased in matured oocytes. In addition, PTGS2 expression increased and POU class 5 homeobox 1 (POU5F1) expression decreased in 4-cell embryos developed from both G+ and G- oocytes. Thus, regardless of toxin type, subclinical mastitis disrupts oocyte cytoplasmic maturation and alters gene expression in association with reduced developmental competence.

Innate immunity and inflammation of the bovine female reproductive tract in health and disease

Mammalian reproductive physiology and the development of viviparity co-evolved with inflammation and immunity over millennia. Many inflammatory mediators contribute to paracrine and endocrine signalling, and the maintenance of tissue homeostasis in the female reproductive tract. However, inflammation is also a feature of microbial infections of the reproductive tract. Bacteria and viruses commonly cause endometritis, perturb ovarian follicle development and suppress the endocrine activity of the hypothalamus and pituitary in cattle. Innate immunity is an evolutionary ancient system that orchestrates host cell inflammatory responses aimed at eliminating pathogens and repairing damaged tissue. Pattern recognition receptors on host cells bind pathogen-associated molecular patterns and damage-associated molecular patterns, leading to the activation of intracellular MAPK and NFκB signalling pathways and the release of inflammatory mediators. Inflammatory mediators typically include the interleukin cytokines IL1β and IL6, chemokines such as IL8, interferons and prostaglandins. This review outlines the mechanisms of inflammation and innate immunity in the bovine female reproductive tract during health and disease condition.

Effects of Escherichia coli- and Staphylococcus aureus-induced mastitis in lactating cows on oocyte developmental competence

Mastitis is associated with decreased fertility in dairy cows. In the current study, we created an experimental model to simulate short-term mastitis by a single intramammary administration of Gram-negative endotoxin ofEscherichia coliorigin (G−), or Gram-positive toxin ofStaphylococcus aureusorigin (G+), to examine the effect of mastitis on oocyte developmental competence. Healthy Holstein cows were synchronized, and follicular fluid (FF) of cows treated with G+ or G− and of uninfected cows (controls) was aspirated from the preovulatory follicles by transvaginal ultrasound procedure. The aspirated FF was used as maturation medium forin vitroembryo production. The distribution of matured oocytes into different cortical granule classes and meiotic stages was affected by G− administration (P<0.05) but not by G+ administration. The proportion of oocytes that cleaved to two- and four-cell stage embryos (44 h postfertilization) was lower in both G+ and G− groups than in controls (P<0.05). Blastocyst formation rate (7–8 days postfertilization) was lower in the G− group (P<0.05) and numerically lower in the G+ group compared with their uninfected counterparts. The total cell number in blastocysts did not differ among groups; however, the apoptotic index was higher in the G+ group (P<0.05), but not in the G− group, relative to controls. Examining mRNA relative abundance in oocytes and early embryos revealed mastitis-induced alterations inPTGS2(COX2),POU5F1, andHSF1but not inSLC2A1(GLUT1) orGDF9. Results indicate a differential disruptive effect of mastitis induced by G− and G+ on oocyte developmental competence in association with alterations in maternal gene expression.

Chronic mastitis is associated with altered ovarian follicle development in dairy cattle

Connection between mastitis and fertility is multifaceted; therefore, several aspects need more elucidation. In particular, the aim was to investigate if naturally occurring chronic mastitis has an effect on ovarian function. At the time of slaughter, a milk sample and both ovaries were collected from 68 cows. The presence and intensity of chronic mastitis was diagnosed by the combined evaluation of bacteriological examination and somatic cell count of the milk of each individual quarter according to the measures of the National Mastitis Council. Animals were divided into 4 groups characterized by a low (n=15), mild (n=14), intense (n=19), or severe (n=16) degree of infection. A count of visible follicles on each ovary was followed by a quantitative analysis of microscopic traits on a selected group of animals (n=16). The latter included the classification and count of the entire preantral follicle population, and the morphometric analysis of the vascular bed extension and connective stroma in the cortical region. Finally, the expression of growth and differentiation factor-9 (GDF-9) was studied. The number of follicles with diameters ranging from 1 to 3 mm and 4 to 7 mm was not affected by the degree of infection. A significant effect of the degree of udder infection was observed on the number of follicles with a diameter larger than 8 mm. Furthermore, the intensity of mastitis had no effect on the number of primordial and primary follicles, but severely affected cows showed a lower number of secondary follicles (0.5±0.1 vs. 0.2±0.03). Quantitative analysis demonstrated a decrease in the density of blood vessels (6.30±1.08 vs. 4.68±0.28) expressed as ratio of vascular bed/total area) and a higher incidence of fibrous stroma (1.60±0.99 vs. 6.04±3.08 expressed as ratio of connective tissue/total area) in the cortical area of the most affected animals. Finally, the level of GDF-9 protein within the oocytes of different follicle size was lower in the animals with the severe form of chronic mastitis (1.34±0.05 vs. 0.78±0.21 expressed as arbitrary units). In conclusion, decreased fertility of cows with chronic mastitis takes place through an effect on the ovary altering the dynamics of folliculogenesis. Within the ovary, this implies a reduction of the vascular bed and an increase in the fibrotic tissue together with a direct effect on oocyte-specific factors as GDF-9, all of which are essential regulatory elements of folliculogenesis.