Metabolic changes in follicular fluid of the dominant follicle in high-yielding dairy cows early post partum

The Roles of GDF-9, BMP-15, BMP-4 and EMMPRIN in Folliculogenesis and In Vitro Fertilization

Growth differentiation factor 9 (GDF-9) contributes to early ovarian development and oocyte survival. Higher concentrations of GDF-9 in follicular fluid (FF) are associated with oocyte nuclear maturation and optimal embryo development. In in vitro fertilization (IVF), GDF-9 affects the ability of the oocyte to fertilize and subsequent embryonic development. Bone morphogenetic protein 15 (BMP-15) is involved in the regulation of ovarian function and affects oocyte development. During IVF, BMP-15 contributes to the formation of competent blastocysts. BMP-15 may play a role in embryo implantation by affecting endometrial receptivity. Bone morphogenetic protein 4 (BMP-4) is involved in the regulation of follicle growth and development and affects granulosa cell (GC) differentiation. In relation to IVF, BMP-4 is important for embryonic development, influences cell fate and differentiation, and plays a role in facilitating embryo-endometrial interactions during the implantation process. Extracellular matrix metalloproteinase inducer (EMMPRIN) is associated with ovulation and follicle rupture, promotes the release of mature eggs, and affects the modification of the extracellular matrix of the follicular environment. In IVF, EMMPRIN is involved in embryo implantation by modulating the adhesive properties of endometrial cells and promotes trophoblastic invasion, which is essential for pregnancy to occur. The purpose of the current article is to review the studies and recent findings of GDF-9, BMP-15, BMP-4 and EMMPRIN as fundamental factors in normal follicular development and in vitro fertilization.

Lipopolysaccharide-binding protein in follicular fluid is associated with the follicular inflammatory status and granulosa cell steroidogenesis in dairy cows

Metabolic stress and subsequent hepatic dysfunction in high-producing dairy cows are associated with inflammatory diseases and declining fertility. Lipopolysaccharide (LPS)-binding protein (LBP) is produced by hepatocytes and controls the immune response, suggesting that it is involved in the pathophysiology of inflammation-related attenuation of reproductive functions during metabolic stress. This study investigated the effect of LBP on the inflammatory status, oocyte quality, and steroidogenesis in the follicular microenvironment of dairy cows. Using bovine ovaries obtained from a slaughterhouse, follicular fluid and granulosa cells were collected from large follicles to evaluate the follicular status of metabolism, inflammation, and steroidogenesis. Cumulus-oocyte complexes were aspirated from small follicles and subjected to in vitro embryo production. The results showed that follicular fluid LBP concentrations were significantly higher in cows with fatty livers and hepatitis than in those with healthy livers. Follicular fluid LBP and LPS concentrations were negatively correlated, whereas LPS concentration showed a positive correlation with the concentrations of non-esterified fatty acids (NEFA) and β-hydroxybutyric acid in follicular fluid. The blastulation rate of oocytes after in vitro fertilization was impaired in cows in which coexisting large follicles had high NEFA levels. Follicular fluid NEFA concentration was negatively correlated with granulosa cell expression of the estradiol (E2) synthesis-related gene (CYP19A1). Follicular fluid LBP concentration was positively correlated with follicular fluid E2 concentration and granulosa cell CYP19A1 expression. In conclusion, follicular fluid LBP may be associated with favorable conditions in the follicular microenvironment, including low LPS levels and high E2 production by granulosa cells.

Female obesity increases the risk of preterm birth of single frozen-thawed euploid embryos: a retrospective cohort study

INTRODUCTION

Obesity has been associated with an increased risk of reproductive failure, especially preterm birth. As preimplantation genetic testing for aneuploidies (PGT-A) is increasingly used worldwide, however, it is still unclear whether body mass index (BMI) has an effect on the preterm birth rate in patients undergoing in vitro fertilization (IVF) with PGT-A when transferring a single euploid blastocyst.

MATERIALS AND METHODS

This retrospective, single-center cohort study included 851 women who underwent the first cycle of frozen-thawed single euploid blastocyst transfer with PGT-A between 2015 and 2020. The primary outcome was the preterm birth rate. Secondary outcomes were clinical pregnancy, miscarriage, ectopic pregnancy, pregnancy complications, and live birth.

RESULTS

Patients were grouped by World Health Organization (WHO) BMI class: underweight (<18.5, n = 81), normal weight (18.5-24.9, n = 637), overweight (25-30, n = 108), and obese (≥30, n = 25). There was no difference in the clinical pregnancy, miscarriage, ectopic pregnancy, pregnancy complication, and live birth by BMI category. In multivariate logistic regression analysis, preterm birth rates were significantly higher in women with overweight (adjusted odds ratio [aOR] 3.18; 95% confidence interval [CI], 1.29-7.80, p = .012) and obese (aOR 1.49; 95% CI, 1.03-12.78, p = .027) compared with the normal weight reference group.

CONCLUSION

Women with obesity experience a higher rate of preterm birth after euploid embryo transfer than women with a normal weight, suggesting that the negative impact of obesity on IVF and clinical outcomes may be related to other mechanisms than aneuploidy.

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.

Embryonic diapause due to high glucose is related to changes in glycolysis and oxidative phosphorylation, as well as abnormalities in the TCA cycle and amino acid metabolism

Introduction

The adverse effects of high glucose on embryos can be traced to the preimplantation stage. This study aimed to observe the effect of high glucose on early-stage embryos.

Methods and results

Seven-week-old ICR female mice were superovulated and mated, and the zygotes were collected. The zygotes were randomly cultured in 5 different glucose concentrations (control, 20mM, 40mM, 60mM and 80mM glucose). The cleavage rate, blastocyst rate and total cell number of blastocyst were used to assess the embryo quality. 40 mM glucose was selected to model high glucose levels in this study. 40mM glucose arrested early embryonic development, and the blastocyst rate and total cell number of the blastocyst decreased significantly as glucose concentration was increased. The reduction in the total cell number of blastocysts in the high glucose group was attributed to decreased proliferation and increased cell apoptosis, which is associated with the diminished expression of GLUTs (GLUT1, GLUT2, GLUT3). Furthermore, the metabolic characterization of blastocyst culture was observed in the high-glucose environment.

Discussion

The balance of glycolysis and oxidative phosphorylation at the blastocyst stage was disrupted. And embryo development arrest due to high glucose is associated with changes in glycolysis and oxidative phosphorylation, as well as abnormalities in the TCA cycle and amino acid metabolism.

A randomized study on the effect of an extended voluntary waiting period in primiparous dairy cows on fertility, health, and culling during first and second lactation

When the voluntary waiting period (VWP), defined as the days between calving and when the cow is eligible to receive the first insemination, is extended, high-yielding dairy cows may have better opportunities to regain energy balance before first insemination. This study investigated the effect of an extended (145-215 days in milk [DIM], n = 280) or conventional (25-95 DIM, n = 251) VWP treatment on fertility, disease incidence, and culling rate in cows during their first lactation. The cows were also followed through a second lactation without intervention regarding VWP, during which the farmers could decide when they wished to start the inseminations. This was done in a randomized-controlled study on 16 high-yielding commercial herds in southern Sweden, containing a total of 531 primiparous cows of the Holstein and Red Dairy Cattle breeds. Data from the Swedish national dairy herd recording scheme collected between August 2018 and September 2021 were used in the analysis, including records on breed, calvings, estrus intensity, inseminations, disease, somatic cell count, culling date, and culling reason. During first lactation, more cows receiving the extended VWP treatment showed strong estrus intensity (score 4-5, 55% vs. 48%) and fewer showed moderate estrus intensity (score 3, 35% vs. 43%) at first insemination, compared with cows receiving the conventional VWP treatment. First service conception rate (FSCR) was higher (67% vs. 51%) and number of inseminations per conception (NINS) was lower (1.6 vs. 2.0) during the first lactation for cows receiving the extended compared with the conventional VWP treatment. For disease incidence rate or culling rate expressed as number of events per cow-time in the study, we found no differences between the cows receiving the 2 VWP treatments in any lactation. Calving to first service interval during second lactation was longer (86 vs. 74 d) for cows with extended compared with conventional VWP. In conclusion, primiparous cows with extended VWP showed improved reproductive functions, in the form of higher estrus intensity, greater FSCR, and lower NINS, during the first lactation. However, we observed no apparent effect on these fertility measures during the following lactation (without VWP intervention) and no differences in disease prevalence or culling between cows receiving the 2 different VWP treatments in either lactation. Compliance with the planned VWP treatment was lower for cows with planned extended compared with planned conventional VWP treatment. We studied the "intention-to-treat" effect (i.e., the results for all cows randomized to each treatment regardless of whether the planned VWP was achieved or not) to identify any bias arising due to degree of compliance. However, we found no difference in culling rate between cows randomized to an extended VWP compared with those randomized to a conventional VWP. These findings can be used to support management decisions on VWP length in high-yielding dairy herds.

Acid-Base, Gas, Ions, and Glucose Analysis in Follicular Fluid in Holstein-Friesian Dairy Cows Is Associated with the Follicle Size in Poland

The lack of fertilization and early pregnancy loss is seen in the quality and maturation of the oocytes. The environment of the first divisions and maturation of the oogonia, which is also a reflection of the quality of the oocyte, is the follicular fluid (FF). Thus, the purpose of this study was to investigate the variations in parameters such as pH, pCO₂, pO₂, standard HCO₃^-, actual HCO₃^-, base excess (BE), base excess of extracellular fluid (BE ecf), ctCO₂, ions: Na⁺, K⁺, actual ionized calcium Ca²⁺, adjusted ionized calcium (at pH 7.4) Ca²⁺ (7.4), Cl^-, anion gap (AnGap), and glucose in FF collected from different size follicles in dairy cattle. The most apparent differences were related to pH, K⁺, and Ca²⁺ 7.4 concentration in comparison to changes in follicle size (p < 0.05). Several trends were also evaluated as an increase in follicular size was followed by an increase in pH, BE, and Ca²⁺ 7.4 value and a decrease in the K⁺ concentration (p < 0.05). In conclusion, there are changes in FF formularies associated with the size of follicles. However, more research is necessary to establish the reference value, which then could be one of the factors describing the quality of the follicle and the developmental potential of the associated oocyte.

Ketone Body β-Hydroxy-Butyrate Sustains Progressive Motility in Capacitated Human Spermatozoa: A Possible Role in Natural Fertility

Background Calorie restriction is recognized as a useful nutritional approach to improve the endocrine derangements and low fertility profile associated with increased body weight. This is particularly the case for dietary regimens involving ketosis, resulting in increased serum levels of ketone bodies such as β-hydroxy-butyrate (β-HB). In addition to serum, β-HB is detected in several biofluids and β-HB levels in the follicular fluid are strictly correlated with the reproductive outcome in infertile females. However, a possible direct role of ketone bodies on sperm function has not been addressed so far. Methods Semen samples were obtained from 10 normozoospermic healthy donors attending the University Andrology Unit as participants in an infertility survey programme. The effect of β-HB on cell motility in vitro was evaluated on isolated spermatozoa according to their migratory activity in a swim-up selection procedure. The effect of β-HB on spermatozoa undergone to capacitation was also assessed. Results Two hours of exposure to β-HB, 1 mM or 4 mM, proved to be ineffective in modifying the motility of freshly ejaculated spermatozoa isolated according to the migratory activity in a swim-up procedure (all p values > 0.05). Differently, sperm maintenance in 4 mM β-HB after capacitation was associated with a significantly higher percentage of sperm cells with progressive motility compared to β-HB-lacking control (respectively, 67.6 ± 3.5% vs. 55.3 ± 6.5%, p = 0.0158). Succinyl-CoA transferase inhibitor abolished the effect on motility exerted by β-HB, underpinning a major role for this enzyme. Conclusion Our results suggest a possible physiological role for β-HB that could represent an energy metabolite in support of cell motility on capacitated spermatozoa right before encountering the oocyte.

Evaluating the impact of the hexosamine biosynthesis pathway and O-GlcNAcylation on glucose metabolism in bovine granulosa cells

Granulosa cells (GCs) of ovarian follicles prefer glucose as a metabolic substrate for growth and maturation. Disruption of glucose utilization via the hexosamine biosynthesis pathway (HBP) impairs O-linked N-acetylglucosaminylation (O-GlcNAcylation) and inhibits proliferation of bovine GCs of both small (3-5 mm) and large (>8.5 mm) antral follicles. Knowing that 2-5% of all glucose in cells is utilized via the HBP, the aim of this study was to characterize glucose metabolism in bovine GCs and determine the impact of the HBP and O-GlcNAcylation on metabolic activity. The GCs were initially cultured in serum-containing medium to confluency and then sub-cultured in serum-free medium in 96 well plates (n = 10 ovary pairs). The cells were exposed to vehicle and inhibitors of the HBP and O-GlcNAcylation for 24 h. Extracellular acidification rate (ECAR; an indicator of glycolysis) and oxygen consumption rate (OCR; an indicator of oxidative phosphorylation) of the GCs were measured using a Seahorse xFe96 Analyzer, including the implementation of glycolytic and mitochondrial stress tests. GCs from small antral follicles exhibited overall greater metabolic activity than GCs from large antral follicles as evidenced by increased ECAR and OCR. Inhibition of the HBP and O-GlcNAcylation had no effect on the metabolic activity of GCs from either type of follicle. The glycolytic stress test indicated that GCs from both types of follicles possessed additional glycolytic capacity; but again, inhibition of the HBP and O-GlcNAcylation did not affect this. Interestingly, inhibition of cellular respiration by 2-Deoxy-D-glucose impaired OCR only in GCs from small antral follicles, but exposure to the mitochondrial stress test had no effect. Conversely, in GCs from large antral follicles, oxidative metabolism was impaired by the mitochondrial stress test and was accompanied by a concomitant increase in glycolytic metabolism. Immunodetection of glycolytic enzymes revealed that phosphofructokinase expression is increased in GCs of small antral follicles compared to large follicles. Inhibition of O-GlcNAcylation impaired the expression of hexokinase only in GCs of small antral follicles. Inhibition of O-GlcNAcylation also impaired the expression of phosphofructokinase, pyruvate kinase and pyruvate dehydrogenase in GCs of both types of follicles, but had no effect on the expression of lactate dehydrogenase. The results indicate that GCs of small antral follicles possess greater aerobic glycolytic capacity than GCs from large antral follicles; but disruption of the HBP and O-GlcNAcylation has little to no impact on metabolic activity.

Seasonal variations in the metabolomic profile of the ovarian follicle components in Italian Mediterranean Buffaloes

The aim of this work was to evaluate the seasonal effect on the metabolomic profile of the ovarian follicle in Italian Mediterranean buffalo to unravel the causes of the reduced competence during the non-breeding season (NBS). Samples of follicular fluid, follicular cells, cumulus cells and oocytes were collected from abattoir-derived ovaries during breeding season (BS) and NBS and analyzed by 1H Nuclear Magnetic Resonance. The Orthogonal Projections to Latent Structures of the Discriminant Analysis showed clear separation into seasonal classes and Variable Importance in Projection method identified differentially abundant metabolites between seasons. Seasonal differences were recorded in metabolite content in all analyzed components suggesting that the decreased oocyte competence during NBS may be linked to alteration of several metabolic pathways. The pathway enrichment analysis revealed that differences in the metabolites between the seasons were linked to glutathione, energy generating and amino acid metabolism and phospholipid biosynthesis. The current work allows the identification of potential positive competence markers in the follicular fluid as glutathione, glutamate, lactate and choline, and negative markers like leucine, isoleucine and β-hydroxybutyrate. These results form a major basis to develop potential strategies to optimize the follicular environment and the IVM medium to improve the competence of oocytes during the NBS.

Sirtuin 3 regulation: a target to alleviate β-hydroxybutyric acid-induced mitochondrial dysfunction in bovine granulosa cells

BACKGROUND

During the transition period, the insufficient dry matter intake and a sharply increased in energy consumption to produce large quantities of milk, high yielding cows would enter a negative energy balance (NEB) that causes an increase in ketone bodies (KBs) and decrease in reproduction efficiency. The excess concentrations of circulating KBs, represented by β-hydroxybutyric acid (BHBA), could lead to oxidative damage, which potentially cause injury to follicular granulosa cells (fGCs) and delayed follicular development. Sirtuin 3 (Sirt3) regulates mitochondria reactive oxygen species (mitoROS) homeostasis in a beneficial manner; however, the molecular mechanisms underlying its involvement in the BHBA-induced injury of fGCs is poorly understood. The aim of this study was to explore the protection effects and underlying mechanisms of Sirt3 against BHBA overload-induced damage of fGCs.

RESULTS

Our findings demonstrated that 2.4 mmol/L of BHBA stress increased the levels of mitoROS in bovine fGCs. Further investigations identified the subsequent mitochondrial dysfunction, including an increased abnormal rate of mitochondrial architecture, mitochondrial permeability transition pore (MPTP) opening, reductions in mitochondrial membrane potential (MMP) and Ca²⁺ release; these dysfunctions then triggered the caspase cascade reaction of apoptosis in fGCs. Notably, the overexpression of Sirt3 prior to treatment enhanced mitochondrial autophagy by increasing the expression levels of Beclin-1, thus preventing BHBA-induced mitochondrial oxidative stress and mitochondrial dysfunction in fGCs. Furthermore, our data suggested that the AMPK-mTOR-Beclin-1 pathway may be involved in the protective mechanism of Sirt3 against cellular injury triggered by BHBA stimulation.

CONCLUSIONS

These findings indicate that Sirt3 protects fGCs from BHBA-triggered injury by enhancing autophagy, attenuating oxidative stress and mitochondrial damage. This study provides new strategies to mitigate the fGCs injury caused by excessive BHBA stress in dairy cows with ketosis.

Contribution of key elements of nutritional metabolism to the development of cystic ovarian disease in dairy cattle

The alteration of signaling molecules involved in the general metabolism of animals can negatively influence reproduction. In dairy cattle, the development of follicular cysts and the subsequent appearance of ovarian cystic disease (COD) often lead to decreased reproductive efficiency in the herd. The objective of this review is to summarize the contribution of relevant metabolic and nutritional sensors to the development of COD in dairy cows. In particular, we focus on the study of alterations of the insulin signaling pathway, adiponectin, and other sensors and metabolites relevant to ovarian functionality, which may be related to the development of follicular persistence and follicular formation of cysts in dairy cattle. The results of these studies support the hypothesis that systemic factors could alter the local scenario in the follicle, generating an adverse microenvironment for the resumption of ovarian activity and possibly leading to the persistence of follicles and to the development and recurrence of COD.

Maternal metabolic health and fertility: we should not only care about but also for the oocyte!

Metabolic disorders due to obesity and unhealthy lifestyle directly alter the oocyte's microenvironment and impact oocyte quality. Oxidative stress and mitochondrial dysfunction play key roles in the pathogenesis. Acute effects on the fully grown oocytes are evident, but early follicular stages are also sensitive to metabolic stress leading to a long-term impact on follicular cells and oocytes. Improving the preconception health is therefore of capital importance but research in animal models has demonstrated that oocyte quality is not fully recovered. In the in vitro fertilisation clinic, maternal metabolic disorders are linked with disappointing assisted reproductive technology results. Embryos derived from metabolically compromised oocytes exhibit persistently high intracellular stress levels due to weak cellular homeostatic mechanisms. The assisted reproductive technology procedures themselves form an extra burden for these defective embryos. Minimising cellular stress during culture using mitochondrial-targeted therapy could rescue compromised embryos in a bovine model. However, translating such applications to human in vitro fertilisation clinics is not simple. It is crucial to consider the sensitive epigenetic programming during early development. Research in humans and relevant animal models should result in preconception care interventions and in vitro strategies not only aiming at improving fertility but also safeguarding offspring health.

The Dynamic Transcription Profiles of Proliferating Bovine Ovarian Granulosa When Exposed to Increased Levels of β-Hydroxybutyric Acid

Ketosis is common in high-yield dairy cows. It is a condition that is characterized by the accumulation of serum β-hydroxybutyric acid (BHBA). Both subclinical ketosis and clinical ketosis can compromise the reproductive performance and cause long-lasting negative effects on reproductive efficiency by affecting the proliferation of follicular and granulosa cells. However, the regulatory mechanisms involved in the development of follicular cells and granulosa cells in cows experiencing subclinical ketosis and clinical ketosis remain largely unknown. To investigate the effect of a ketosis-triggered increase in BHBA on bovine follicular granulosa cell development, we detected a significant reduction in the proliferation of granulosa cells (P &lt; 0.05) in the BHBA-1.2 mM and BHBA-2.4 mM groups and a significant increase in the number of granulosa cells in the G1 phase of the cell cycle (P &lt; 0.05). RNA-seq and trend analysis were used to identify differentially expressed genes by comparing three clusters: low-concentration response to 1.2 mM BHBA, high-concentration response to 2.4 mM BHBA, and the similar trend (up or down) response following BHBA concentration increased. GO and KEGG enrichment analyses were performed separately for each cluster. Analysis showed that two novel down-regulated genes (G0S2 and S100A6), which are associated with cell proliferation and cycle progression, were enriched in the low-concentration response to 1.2 mM BHBA. Another differentially expressed gene (PARP), which plays a role in the apoptotic pathway, was enriched in the high-concentration response to 2.4 mM BHBA. We also found that CYP27B1 and CYP17A1, which are associated with Ca2+ homeostasis and estrogen synthesis, were enriched in a similar trend response. In conclusion, we describe the dynamic transcription profiles of granulosa cells under different levels of β-hydroxybutyric stress and report key regulators that may underlie the detrimental effects on the development of follicles and granulosa cells, thus representing potential therapeutic targets to improve fertility in dairy cows with subclinical ketosis or clinical ketosis.

Characterization of histone lysine β-hydroxybutyrylation in bovine tissues, cells, and cumulus-oocyte complexes

Besides their canonical roles as energy sources, short-chain fatty acids act as metabolic regulators of gene expression through histone posttranslational modifications. Ketone body β-hydroxybutyrate (BHB) causes a novel epigenetic modification, histone lysine β-hydroxybutyrylation (Kbhb), which is associated with genes upregulated in starvation-responsive metabolic pathways. Dairy cows increase BHB in early lactation, and the effects of this increase on cellular epigenomes are unknown. We searched for and identified that Kbhb is present in bovine tissues in vivo and confirmed that this epigenetic mark is responsive to BHB in bovine and human fibroblasts cultured in vitro in a dose-dependent manner. Maturation of cumulus-oocyte complexes with high concentrations of BHB did not affect the competence to complete meiotic maturation or to develop until the blastocyst stage. BHB treatment strongly induced H3K9bhb in cumulus cells, but faintly in oocytes. RNA-seq analysis in cumulus cells indicated that BHB treatment altered the expression of 345 genes. The downregulated genes were mainly involved in glycolysis and ribosome assembly pathways, while the upregulated genes were involved in mitochondrial metabolism and oocyte development. The genes and pathways altered by BHB will provide entry points to carry out functional experiments aiming to mitigate metabolic disorders and improve fertility in cattle.

Increased β-hydroxybutyrate (BHBA) concentration affect follicular growth in cattle

Metabolic stress conditions caused by negative energy balance (NEB) have been associated with reduced fertility in cows. β-hydroxybutyrate (BHBA) is the main circulating ketone body, which accumulates within follicular fluid. The aim of this study was to evaluate the effects of BHBA on follicle growth and on ovulatory mechanisms in cattle. At 72 h after intrafollicular injection, there was a decrease in follicular diameter in BHBA group compared to control (P = 0.02). Furthermore, follicle growth rate was reduced post-treatment with BHBA in comparison to the control group (P < 0.03). The BHBA intrafollicular injection in follicles ≥ 12 mm, however, did not affect E2 and P4 concentrations in the follicular fluid. In addition, the relative abundance of genes involved in the ovulatory cascade (ADAM 17, AREG, EREG, PTGS2), steroidogenesis (CYP19A1, 3BHSD, STAR), cellular stress (SOD1, CAT, GPX1, HSPA5, XBP1s, XBP1u, ATF4, ATF6), monocarboxylic acid transporters (SLC16A1, SLC16A7) and apoptosis (XIAP) was similar between groups. In conclusion, the results of this study indicate that the increase in intrafollicular concentrations of BHBA affects follicular growth, but it does not compromise the ovulatory cascade and cellular homeostasis in bovine granulosa cells.

Reproductive Consequences of Electrolyte Disturbances in Domestic Animals

Electrolyte balance is essential to maintain homeostasis in the body. The most crucial electrolytes are sodium (Na+), potassium (K+), magnesium (Mg2+), chloride (Cl−), and calcium (Ca2+). These ions maintain the volume of body fluids, and blood pressure, participate in muscle contractions, and nerve conduction, and are important in enzymatic reactions. The balance is mainly ensured by the kidneys, which are an important organ that regulates the volume and composition of urine, together with which excess electrolytes are excreted. They are also important in the reproductive system, where they play a key role. In the male reproductive system, electrolytes are important in acrosomal reaction and sperm motility. Sodium, calcium, magnesium, and chloride are related to sperm capacitation. Moreover, Mg2+, Ca2+, and Na+ play a key role in spermatogenesis and the maintenance of morphologically normal spermatozoa. Infertility problems are becoming more common. It is known that disturbances in the electrolyte balance lead to reproductive dysfunction. In men, there is a decrease in sperm motility, loss of sperm capacitation, and male infertility. In the female reproductive system, sodium is associated with estrogen synthesis. In the contraction and relaxation of the uterus, there is sodium, potassium, and calcium. Calcium is associated with oocyte activation. In turn, in women, changes in the composition of the follicular fluid are observed, leading to a restriction of follicular growth. Imbalance of oocyte electrolytes, resulting in a lack of oocyte activation and, consequently, infertility.

Cholesterol supports bovine granulosa cell inflammatory responses to lipopolysaccharide

During bacterial infections of the bovine uterus or mammary gland, ovarian granulosa cells mount inflammatory responses to lipopolysaccharide (LPS). In vitro, LPS stimulates granulosa cell secretion of the cytokines IL-1α and IL-1β, and the chemokine IL-8. These LPS-stimulated inflammatory responses depend on culturing granulosa cells with serum, but the mechanism is unclear. Here we tested the hypothesis that cholesterol supports inflammatory responses to LPS in bovine granulosa cells. We used granulosa cells isolated from 4-8 mm and > 8.5 mm diameter ovarian follicles and manipulated the availability of cholesterol. We found that serum or follicular fluid containing cholesterol increased LPS-stimulated secretion of IL-1α and IL-1β from granulosa cells. Conversely, depleting cholesterol using methyl-β-cyclodextrin diminished LPS-stimulated secretion of IL-1α, IL-1β and IL-8 from granulosa cells cultured in serum. Follicular fluid contained more high-density lipoprotein cholesterol than low-density lipoprotein cholesterol, and granulosa cells expressed the receptor for high-density lipoprotein, scavenger receptor class B member 1 (SCARB1). Furthermore, culturing granulosa cells with high-density lipoprotein cholesterol, but not low-density lipoprotein or very low-density lipoprotein cholesterol, increased LPS-stimulated inflammation in granulosa cells. Cholesterol biosynthesis also played a role in granulosa cell inflammation because RNA interference of mevalonate pathway enzymes inhibited LPS-stimulated inflammation. Finally, treatment with follicle-stimulating hormone, but not luteinizing hormone, increased LPS-stimulated granulosa cell inflammation, and follicle-stimulating hormone increased SCARB1 protein. However, changes in inflammation were not associated with changes in oestradiol or progesterone secretion. Taken together these findings imply that cholesterol supports inflammatory responses to LPS in granulosa cells.

Maladaptation to the transition period and consequences on fertility of dairy cows

After parturition, dairy cows undergo a plethora of metabolic, inflammatory, and immunologic changes to adapt to the onset of lactation. These changes are mainly due to the homeorhetic shift to support milk production when nutrient demand exceeds dietary intake, resulting in a state of negative energy balance. Negative energy balance in postpartum dairy cows is characterized by upregulated adipose tissue modelling, insulin resistance, and systemic inflammation. However, half of the postpartum cows fail to adapt to these changes and develop one or more types of clinical and subclinical disease within 5 weeks after calving, and this is escorted by impaired reproductive performance in the same lactation. Maladaptation to the transition period exerts molecular and structural changes in the follicular and reproductive tract fluids, the microenvironment in which oocyte maturation, fertilization, and embryo development occur. Although the negative effects of transition diseases on fertility are well-known, the involved pathways are only partially understood. This review reconstructs the mechanism of maladaptation to lactation in the transition period, explores their key (patho)physiological effects on reproductive organs, and briefly describes potential carryover effects on fertility in the same lactation.

Dietary Fatty Acid Intakes and the Outcomes of Assisted Reproductive Technique in Infertile Women

Background

The purpose of this study was evaluating the relationship between fatty acid (FA) intakes and the Assisted Reproductive Technique (ART) outcomes in infertile women.

Methods

In this descriptive longitudinal study, a validated food frequency questionnaire (FFQ) was used to measure dietary intakes among 217 women with primary infertility seeking ART treatments at Isfahan Fertility and Infertility Center, Isfahan, Iran. The average number of total and metaphase II (MII) oocytes, the fertilization rate, the ratio of good and bad quality embryo and biochemical and clinical pregnancy were assessed. Analyses were performed using mean, standard deviation, Chi-square test, ANOVA, ANCOVA, logistic regression.

Results

A total of 140 women were finally included in the study. There was a positive relationship between the average number of total and MII oocytes and the amount of total fatty acids (TFAs), saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs), linoleic acids, linolenic acids, and oleic acids intakes, while eicosapentaenoic acids (EPAs) and docosahexaenoic acids (DHAs) intakes had an inverse relationship. Consuming more amounts of TFAs, SFAs, PUFAs, MUFAs, linoleic acids, and oleic acids was associated with the lower fertilization rate, whereas the consumption of linolenic acids and EPAs increased the fertilization rate. The ratio of good quality embryo was directly affected by the amount of PUFAs intakes. Additionally, there was a negative correlation between the amount of SFAs intakes and the number of pregnant women.

Conclusion

TFAs, SFA, PUFA, and MUFA intakes could have both beneficial and adverse impacts on ART outcomes.

Current knowledge and the future potential of extracellular vesicles in mammalian reproduction

Extracellular vesicles (EVs), which contain various functional classes of vesicles, namely exosomes, microvesicles, and apoptotic bodies, represent the major nano-shuttle to transfer bioactive molecules from donor to recipient cells to facilitate cell-to-cell communication in the follicular, oviduct, and uterine microenvironments. In addition to transferring various molecular cargos in the form of miRNAs, mRNAs, proteins, lipids, and DNA molecules, the relative proportion of those molecular cargos in the reproductive fluids can be associated with the physiological and pathological condition of the host animal. Inside the follicle, EV-mediated circulation of miRNAs has been reported to be associated with the growth status of the enclosed oocytes, the metabolic status, and the advanced maternal aging of the animal. Importantly, EVs have the potential to protect their cargo molecules from extracellular degradation or modification while travelling to the recipient cells. This fact together with the enormous availability in almost all biological fluids and spent culture media make them attractive in the search for biomarkers of oocyte/embryo developmental competence, receptive maternal environment and a multitude of reproductive pathophysiological conditions. One of the key factors that have contributed to the lower efficiency of assisted reproductive technologies (ART) is the absence of several maternal in vivo factors in the ART procedures. For this, several studies have been conducted to supplement various components present in the follicular and oviductal fluids into the existing ART procedures and significant positive impacts have been observed in terms of embryo cleavage rate, blastocyst rate, resistance to stress, and survival after cryopreservation. The potential of EVs in shuttling protective messages against environmental and physiological stressors has been evidenced. The effective use of the EV-coupled molecular signals against stress-associated conditions has the potential to pave the path for the application of these protective signals against oxidative stress-associated pathological conditions including PCOS, ageing, and endometritis. In this review, we provide current knowledge and potential future use of EVs as remedies in reproductive pathophysiological conditions, mainly in follicular and oviductal microenvironments.

Effects of hydrogenated fat-spray-coated β-carotene supplement on plasma β-carotene concentration and conception rate after embryo transfer in Hanwoo beef cows

We hypothesised that hydrogenated fat (HF)-spray-coated β-carotene (βC) supplement could be used to increase plasma βC concentration and conception rates after embryo transfer (ET) in Hanwoo beef cows. In Experiment 1, 12 multiparous Hanwoo cows were fed one of four experimental diets in a triplicate 4 × 4 Latin square design for a 28-day period. Treatments included no βC addition (control), HF-uncoated βC (HFuβC), HF-spray-coated βC (HFβC), and HF-spray-coated βC and vitamin A (HFβCA). The cows under βC-supplemented treatments were fed 400 mg/day of βC, and a daily intake for vitamin A of HFβCA treatment was 30 000 IU/day as retinyl acetate. Blood was collected on days 0, 26, 27, and 28 to analyse βC and other metabolite concentrations. In Experiment 2, 199 Hanwoo cows with low fertility were randomly assigned to either control (n = 99) or HFβC treatments (n = 100) based on the results of Experiment 1. The oestrus of the cows was synchronised for ET. The HFβC group was fed from 4 weeks before to 4 weeks after ET with a daily intake of 400 mg βC. Pregnancy for conception rates was diagnosed on day 60 after ET, and blood was collected for βC concentrations on the day before ET. Supplementing βC resulted in a high plasma βC concentration (P < 0.001). Supplementing HFβC or HFβCA resulted in higher βC concentrations than HFuβC (P < 0.001); however, there was no difference between HFβC and HFβCA groups. Plasma retinol concentration was lower in the HFβCA treatment than in the control and HFβC groups (P < 0.05). Blood metabolites were unaffected by the treatments. The retinol:βC ratio was lower in the βC-supplemented treatments than in the controls, and was lower in HFβC and HFβCA than in HFuβC groups (P < 0.001). Plasma βC concentration was positively correlated with plasma high-density lipoprotein, low-density lipoprotein, and total cholesterol (P < 0.05). Plasma retinol concentration was negatively associated with plasma protein (P < 0.01), but positively associated with plasma creatinine (P < 0.001) and urea (P < 0.01). Supplementing HFβC to low-fertility cows resulted in higher plasma βC concentration (P < 0.001) and conception rates (P = 0.024) than those in the controls. In conclusion, HFβC had a better bioavailability than HFuβC, and an increase in conception rates by supplementing HFβC may be beneficial for producing more calves given the low pregnancy rates of bovine ET in Korea.

Fertility risk factors in transferring Japanese Black embryos into dairy heifers: An epidemiological study

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Epidemiological study of embryo transfers of japanese black (JB) embryos.

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JB's bloodline combination was also found to be a risk factor for embryo fertility.

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Success of JB embryo transfer may depend on differences in genetic background.

The aims of this study were 1) to summarize the current status of Japanese Black (JB) embryo transfer into Holstein heifers, which is carried out on a commercial basis in Japan, and 2) to reveal fertility risk factors, including those from the environment (year and season of transfer), recipient (age, number of transfers, clinical status of the ovaries) and embryo (quality, stage, state, genetic background). We used data from 4467 JB fresh or frozen embryo transfers into Holstein heifers conducted by Zen-noh Embryo Transfer Center during 2016–2018, and the differences in fertility risk due to factors related to the environment, recipient, and embryo were statistically evaluated. Differences in fertility risk due to each variable were observed, leading to significant differences in fertility with respect to year of transfer, embryo quality, embryo state, and embryo breed. These results suggest that the fertility of JB embryos might depend on differences in genetic background. There have been no previous reports of differences in embryo fertility due to the differences among JB's bloodline combinations. In the future, overall reproductive efficiency must be monitored, including the effects of different bloodline combinations on the success of embryo recovery and transfer.

The effects of glutathione ethyl ester in in vitro maturation on the developmental ability of oocytes derived from cattle with liver abnormalities

The main objectives of this study was to identify the effects of a relationship of hyper-concentration of Gamma-glutamyltransferase (γ-GTP) in follicle fluid (FF) on the levels of glutathione (GSH)/reactive oxygen species (ROS) in oocytes and subsequent embryo development in cattle with abnormal livers. Furthermore, we investigated the effect of supplementing in vitro maturation medium with glutathione ethyl ester (GSH-OEt) on the subsequent developmental potential of oocytes from such cattle. We used a control group of cattle (with normal livers) and a liver disorder (LD) group, in which the liver was diagnosed as being abnormal. In experiment 1, the LD group was divided to two subgroups according to the concentration of γ-GTP in FF: a low group (≤50 IU/L; the low LD group), and a high group (>50 IU/L: the high LD group). Cumulus oocyte-complexes (COCs) were matured and fertilized in vitro and then cultured to the blastocyst stage. The levels of GSH and ROS in the matured oocytes after IVM were then assessed in each group. On day 7 after fertilization, embryo cleavage and development were assessed. We found that the rate of development to the blastocyst stage was significantly lower in the high LD group than in the control group and the low LD group. The levels of GSH in matured oocytes were significantly lower in the high LD group than in the control group and low LD group. The levels of ROS in matured oocytes was significantly higher in the high LD group than in the control group and the low LD group. In experiment 2, COCs from cattle in the high LD group were matured in m-199 supplemented with 5 mM GSH-OEt, then IVF and IVC was performed for 7 days. The GSH levels were determined in some COCs after IVM. The supplementation of media with GSH-OEt during IVM increased the levels of GSH in mature oocytes and improved the rate of blastocyst development compared with the control group. In conclusion, GSH-OEt supplementation to media during IVM can improve the developmental potential of oocytes in liver-diseased cattle with high γ-GTP concentrations in the FF by increasing intracellular GSH synthesis and scavenging ROS.

Endocrine and Electrolyte Balances during Periovulatory Period in Cycling Mares

Simple Summary

This study provides new evidence on the physiological mechanisms involved in the electrolyte balance during periovulatory period in cycling mares. The interrelationships among adrenocorticotropic hormone (ACTH), cortisol (CORT), aldosterone (ALD) and electrolytes (sodium—Na⁺, potassium—K⁺ and chloride—Cl⁻) were evaluated. The simultaneous increase in ACTH, CORT and ALD toward the time of ovulation could suggest the involvement of the adrenocortical pituitary axis in the ovulatory mechanisms, contributing at the same time to the maintenance of electrolyte homeostasis.

Abstract

In cycling females, the periovulatory period is characterized by stimulation of the hypothalamic pituitary adrenal (HPA) axis. The aim of present study was to analyze the pattern and interrelationships among adrenocorticotropic hormone (ACTH), cortisol (CORT), aldosterone (ALD) and electrolytes (sodium—Na⁺, potassium—K⁺ and chloride—Cl⁻) during periovulatory period in cycling mares. Venous blood samples were obtained daily from a total of 23 Purebred Spanish broodmares, aged 7.09 ± 2.5 years, from day −5 to day +5 of estrous cycle, considering day 0, the day of ovulation. Plasma ACTH was measured by a fluorescent immunoassay kit, serum CORT and ALD by means of a competitive ELISA immunoassay, and plasma Na⁺, K⁺ and Cl⁻ were quantified by an analyzer with selective electrodes for the three ions. ACTH showed higher concentrations at day 0 compared to days −5 to −1 and +1 to +3 (p < 0.05). CORT showed higher concentrations at day 0 compared to days −5 to −2 and +1 to +5 (p < 0.05). ALD showed higher concentrations at day 0 compared to days −5 to −2 (p < 0.05) and +2 (p < 0.05). Na⁺ and Cl⁻ showed higher concentrations at day 0, compared to day −5 and +5. K⁺ showed lower concentrations at day 0 compared to day +1 (p < 0.05). The significant correlations obtained between ACTH and CORT (r = 0.20) and between ACTH and ALD (r = 0.32) suggest that although ACTH may have an effect both on CORT and ALD, there are other very important determinants that could be considered. Hence, it is possible to presume that the pituitary adrenocortical response and ALD may be involved in the ovulatory mechanisms without a direct relation with electrolyte pattern.

First postpartum ovulation, metabolites and hormones in follicular fluid and blood in transition dairy cows supplemented with a Saccharomyces cerevisiae fermentation product

We hypothesized that feeding a Saccharomyces cerevisiae fermentation product (SCFP) from -4 through +7 wk (calving = Day 0) facilitates early first postpartum ovulation and alters blood and follicular fluid concentrations of glucose, beta-hydroxybutyrate (BHB), free fatty acids (FFA), and steroid hormones favorable to subsequent fertility. Holstein cows were fed individually a SCFP product (n = 24) or served as controls (n = 23). Blood samples were collected at wk -4 and -2 from expected calving and at 1, 2, 5, and 7 wk postpartum to determine plasma concentrations of FFA and BHB. Early spontaneous ovulation (progesterone > 1 ng/mL or corpus luteum presence by postpartum median Day 33) or late ovulation was determined. Plasma FFA in weekly samples was not affected by SCFP supplementation, but FFA was greater (P < 0.01; week by ovulation status) in late compared with early ovulating cows during and after postpartum wk 2. Plasma BHB in weekly samples was greater (P = 0.03) in SCFP than control cows and tended (P = 0.06) to be greater in late than early ovulating cows. Cows were exposed to ovulation synchronization (GnRH, PGF_2α, and GnRH on Days 33, 40, and 43 ± 3, respectively). Transvaginal dominant follicle aspiration was conducted at Day 50, 7 d after GnRH on Day 43. Metabolites (FFA, BHB, and glucose) and steroid hormones (progesterone, androstenedione, and estradiol) measured in follicular fluid and blood samples collected at aspiration revealed that androstenedione in serum was numerically less (P = 0.11) in SCFP-treated compared with control cows, whereas androstenedione in serum was less (P < 0.05) in late than early ovulating cows. Concentrations of BHB (r = 0.75) and glucose (r = 0.52) in follicular fluid were positively correlated (P < 0.01) with those in blood. Body weight at calving and Day 42 was less (P ≤ 0.05), and energy balance through Days 28 and 42 was more positive (P < 0.05) in early than late ovulating cows and in SCFP-supplemented compared with control cows (P < 0.05). Dry matter intake, daily milk yield, and yields of fat, protein, lactose, and total solids were less (P < 0.01) in early compared with late ovulating cows, whereas milk fat percentage was increased (P < 0.01) by SCFP supplementation. We conclude that elevated postpartum BHB and FFA in plasma, greater negative energy balance, and greater milk yield and components were associated with later postpartum ovulation, but metabolites and steroid hormones in blood and follicular fluid were unaffected by SCFP treatment or ovulation status except for androstenedione.

Capacity of Trolox to improve the development and quality of metabolically compromised bovine oocytes and embryos invitro during different windows of development

Trials to improve oocyte developmental competence under metabolic stress by using antioxidants may start before or after oocyte maturation. In the present conceptual study, we aimed to identify the most efficient timing of antioxidant application in relation to a metabolic insult using a bovine invitro embryo production model. Pathophysiological concentrations of palmitic acid (PA) were used to induce metabolic stress during oocyte maturation or embryo development. Trolox (TR; antioxidant) treatment prior to, during or after the PA insult was tested to evaluate the protective, neutralising and rescuing capacity of TR respectively. Changes in embryo developmental competence, mitochondrial activity, reactive oxygen species (ROS) concentrations, blastocyst cell allocation and apoptosis and cell stress-related gene expression were monitored. The improvement in developmental capacity was most obvious when oocytes were preloaded with TR before the PA insult. This protective effect could be explained by the observed combination of increased mitochondrial activity with reduced ROS production. This resulted in blastocysts with normal cell counts and apoptosis, as well as increased nuclear factor erythroid 2-related factor 2 (NRF2) expression (a marker for redox regulatory processes) and normalised the expression of the mitochondrial transcription factor A (TFAM), a marker of mitochondrial biogenesis. These results indicate that 'pretreatment' of oocytes with antioxidants produces embryos that seem to be more resilient to a metabolic stress insult.

Extracellular Vesicles as Mediators of Environmental and Metabolic Stress Coping Mechanisms During Mammalian Follicular Development

Extracellular vesicles are evolutionarily conserved nano-sized phospholipid membraned structures and released from virtually all types of cells into the extracellular space. Their ability to carry various molecular cargos (mRNA, miRNA, proteins, and lipids) from one cell to the other to exert functional impact on the target cells enables them to play a significant role in cell to cell communication during follicular development. As the molecular signals carried by extracellular vesicles reflect the physiological status of the cells of origin, they are expected to mediate any effect of environmental or metabolic stress on the follicualr cells and the growing oocyte. Recent studies have evidenced that reproductive cells exposed to various environmental stressors (heat and oxidative stress) released extracellular vesicles enriched with mRNA and miRNA associated with stress response mechanisms. Moreover, the metabolic status of post-calving cows could be well-reflected in the follicular extracellular vesicle's miRNA profile, which signified the potential role of extracellular cellular vesicle molecular signals in mediating the effect of metabolic stress on follicular and oocyte development. In the present review, the potential role of extracellular vesicles in mediating the effect of environmental and metabolic stress in various reproductive cells and oocytes are thoroughly discussed Moreover, considering the importance of extracellular vesicles in shuttling protective or rescuing molecular signals during stress, their potential usage as means of targeted delivery of molecules to mitigate the effect of stress on oocytes are addressed as the focus of future research.

Role of extracellular vesicles during oocyte maturation and early embryo development

The follicle is a dynamic microenvironment in the ovary where the oocyte develops. Intercellular communication between somatic cells and the oocyte inside the follicle is essential to generate a competent gamete. Extracellular vesicles are nanoparticles secreted by cells that mediate cell-to-cell communication in the follicle microenvironment and can be obtained from the follicular fluid. These extracellular vesicles have been studied as biomarkers and supplementation tools to mimic physiological conditions during assisted reproductive techniques because they are vehicles of bioactive molecules. Therefore, this paper reviews the importance of changes in the ovarian follicle and the effects of extracellular vesicles from follicular fluid during oocyte maturation and early embryo development. Finally, we propose that is important to consider the source of the extracellular vesicles to improve diagnostic methods and to increase invitro embryo production.

Association between Body Mass Index and Reproductive Outcome in Women with Polycystic Ovary Syndrome Receiving IVF/ICSI-ET

Objective

To examine the association between body mass index (BMI) and the outcome of in vitro fertilization or intracytoplasmic sperm injection embryo transfer- (IVF/ICSI-ET) assisted reproduction in women with polycystic ovary syndrome (PCOS) receiving the ultra-long agonist protocol.

Methods

We retrospectively identified all women receiving IVF/ICSI-ET for the first time using the ultra-long protocol between January 2013 and January 2018 at our hospital. Only women at ≤35 years of age receiving the first cycle were analyzed.

Results

A total of 1782 women were included in the analysis: 42 were underweight, 742 were overweight, 198 were obese, and 800 were normal weight. Gonadotropin dosage and duration were comparable between underweight and normal weight groups but were significantly higher/longer in overweight and obese groups (P < 0.008). The number of oocytes retrieved was significantly lower in overweight and obese groups than in the normal weight group (P < 0.008). The number of transferable embryos was significantly higher in normal weight group than overweight and obese groups (P < 0.008). Embryo implantation rate, clinical pregnancy rate, full-term birth rate, and live birth rate did not differ among the 4 groups. The cycle cancellation rate was lower in the overweight and obese group than normal weight group (P < 0.008). The miscarriage rate was higher in the obese group than the normal weight group (P < 0.008). In multivariate logistic regression analysis, abnormal BMI was an independent risk for miscarriage (OR: 1.069, 95% CI 1.020, 1.122; P = 0.006).

Conclusion

Overweight and obesity are associated with poor outcomes in PCOS patients receiving ultra-long protocol. Measures to reduce body weight should be encouraged in overweight and obese PCOS women at ≤35 years of age prior to assisted reproductive technology (ART).

Glutathione-dependent enzymes in the follicular fluid of the first-retrieved oocyte and their impact on oocyte and embryos in polycystic ovary syndrome: A cross-sectional study

Background

Oxidative stress and GSH-dependent antioxidant system plays a key role in the pathogenesis of polycystic ovary syndrome (PCOS).

Objective

We compared glutathione peroxidase (GPx) and glutathione reductase activities and reduced glutathione (GSH) levels in serum and follicular fluid (FF) of the first-retrieved follicle and their impact on quality of oocyte and embryo in PCOS women undergoing IVF.

Materials and Methods

This cross sectional study was conducted on 80 pairs of blood samples and FF of the first-retrieved follicle from PCOS women, at the Infertility center of Ghadir Mother and Child Hospital. The mean activity of GPx and GR, also GSH levels in the serum and FF were compared to the quality of the first follicle and resultant embryo.

Results

Retrieved oocytes included 53 (66.25%) MII, 17 (21.25%) MI, and 10 (12.5%) germinal vesicles; after IVF 42 (52.50%) embryos with grade I and 11 (13.75%) with grade II were produced. The mean values for all three antioxidants were higher in the FF compared to serum (p < 0.001). Also all of the mean measured levels were significantly higher in the FF of the MII oocytes compared to that of oocytes with lower grades (p = 0.012, 0.006 and 0.012, respectively). The mean GPX activity and GSH levels were significantly higher in the serum (p = 0.016 and 0.012, respectively) and FF (p = 0.001 for both) of the high-quality grade I embryos.

Conclusion

GSH-dependent antioxidant system functions more efficiently in the FF of oocytes and embryos with higher quality.

Metabolism-associated genome-wide epigenetic changes in bovine oocytes during early lactation

Dietary intake in early lactating cows is outmatched by milk production. These cows experience a negative energy balance, resulting in a distinct blood metabolism and poor reproductive function due to impaired ovulation and increased embryo loss. We hypothesize that oocytes from lactating cows undergoing transient metabolic stress exhibit a different epigenetic profile crucial for developmental competence. To investigate this, we collected oocytes from metabolically-profiled cows at early- and mid-postpartum stages and characterized their epigenetic landscape compared with control heifers using whole-genome bisulfite sequencing. Early-postpartum cows were metabolically deficient with a significantly lower energy balance and significantly higher concentrations of non-esterified fatty acids and beta-hydroxybutyrate than mid-postpartum animals and control heifers. Accordingly, 32,990 early-postpartum-specific differentially methylated regions (DMRs) were found in genes involved in metabolic pathways, carbon metabolism, and fatty acid metabolism, likely descriptive of the epigenetic regulation of metabolism in early-postpartum oocytes. DMRs found overlapping CpG islands and exons of imprinted genes such as MEST and GNAS in early-postpartum oocytes suggest that early lactation metabolic stress may affect imprint acquisition, which could explain the embryo loss. This whole-genome approach introduces potential candidate genes governing the link between metabolic stress and the reproductive outcome of oocytes.

Follicular environment as a predictive tool for embryo development and kinetics in cattle

Follicular fluid composition and the transcription pattern of granulosa cells were analysed to better comprehend associations between embryo development and morphokinetics. Bovine follicles were punctured and their respective follicular fluid and granulosa cells were collected. Cumulus-oocyte complexes derived from these follicles were matured and fertilised invitro. Embryo morphology and kinetics were evaluated at 40h after insemination, when embryos were classified as fast (FCL, four or more cells), slow (SCL, 2-3 cells) or non-cleaved (NCL). Their development was followed until the blastocyst stage. Glucose, pyruvate, cholesterol and oestradiol were quantified in the follicular fluid and the transcription pattern of 96 target genes was evaluated in granulosa cells by large-scale quantitative reverse transcription polymerase chain reaction. Follicular fluid from the blastocyst group had increased levels of glucose, total cholesterol and pyruvate compared to the non-blastocyst group, whereas higher levels of oestradiol were observed in the follicular fluid of embryos and blastocysts with fast cleavage. The transcriptional pattern revealed altered metabolic pathways between groups, such as lipid metabolism, cellular stress and cell signalling. In conclusion, both follicular fluid and granulosa cells are associated with the possibility of identifying follicles that may generate embryos with high potential to properly develop to the blastocyst stage.

Lipid profile of bovine blastocysts exposed to insulin during in vitro oocyte maturation

Insulin is a key hormone with important functions in energy metabolism and is involved in the regulation of reproduction. Hyperinsulinaemia is known to impair fertility (for example, in obese mothers); therefore, we aimed to investigate the impact of elevated insulin concentrations during the sensitive period of oocyte maturation on gene expression and lipid profiles of the bovine Day-8 embryo. Two different insulin concentrations were used during in vitro oocyte maturation (INS10=10µgmL-1 and INS0.1=0.1µgmL-1) in order to observe possible dose-dependent effects or thresholds for hyperinsulinaemia in vitro. By investigating gene expression patterns by an mRNA microarray in combination with lipid profile analysis by desorption electrospray ionisation-mass spectrometry (DESI-MS) of embryos derived from insulin-treated oocytes, we gained further insights regarding molecular responses of embryos to insulin provocation during the first days of development. Lipid metabolism appeared to be influenced on multiple levels according to gene expression results but the profiles collected in positive-ion mode by DESI-MS (showing mostly ubiquinone, cholesteryl esters and triacylglycerols) did not differ significantly from controls. There are parallels in follicular development of ruminants and humans that make this bovine model relevant for comparative research on early human embryonic development during hyperinsulinaemia.

Hyperketolactia occurrence before or after artificial insemination is associated with a decreased pregnancy per artificial insemination in dairy cows

The reproductive parameters of dairy cattle have continuously declined worldwide over the last 50 years. Nutritional imbalances are identified as risk factors for this decrease of reproductive performance. The present paper aims to quantify the decrease in the pregnancy per artificial insemination (P/AI) in the case of high milk ketones before and after AI. A total of 388,731 test-day from the Brittany Milk Recording Program in France from 226,429 cow-lactations were provided for this trial. For each test-day, information about lactation characteristics, date of AI, date of the following calving, and acetone and β-hydroxybutyrate (BHB) values were included. Ketones were predicted by Fourier transform mid-infrared spectroscopy using MilkoScan Foss analyzers (Foss, Hillerød, Denmark). Many thresholds were evaluated to define cows with hyperketolactia. Hyperketolactia statuses were then categorized into 1 of 4 possible classes according to the milk ketone dynamics for each AI and each threshold of acetone or BHB values (low-low, high-low, low-high, and high-high) within 20 d before and after AI. Similarly, the dynamics of udder health were characterized by changes in somatic cell counts measured at the same test day as ketone bodies. A logistic regression with a Poisson correction was performed to explain the relationship of P/AI with milk ketones and somatic cell count dynamics. Predicted acetone and BHB ranged from -0.51 to 4.92 mM (mean = 0.08 mM, SD = 0.10 mM) and -0.62 to 5.85 mM (mean = 0.07 mM, SD = 0.1 mM), respectively. Hyperketolactia defined by high acetone levels before AI was not associated with decreased P/AI, but high acetone levels after AI were associated with a >10% reduction in P/AI for all thresholds >0.10 mM. Hyperketolactia, defined by high BHB values before, after, or before and after AI, was associated with a 6 to 14% reduction in P/AI compared with cows with low BHB values. These associations are lower than those reported in previous trials in which blood ketones were used. High ketones in advanced lactation are likely to be the result of various primary disorders (secondary ketosis). Because the present work demonstrated that this situation is considered a risk factor for deteriorated reproductive performance, we suggest that high ketones in early and advanced lactation should be of interest to farm advisors.

Can follicular Emmprin and BMP 4 levels predict ICSI outcome?

PURPOSE

To evaluate the relationship of clinical pregnancy rates with bone morphogenetic proteins 2-4-7 (BMP 2, 4, 7), growth differentiation factor 9 (GDF 9), and Emmprin levels in follicular fluid of intracytoplasmic sperm injection patients.

METHODS

Follicular fluid of 77 patients who underwent ICSI procedure was collected during the oocyte retrieval procedure. And follicular fluid levels of BMP 2, BMP 4, BMP 7, GDF 9, and Emmprin (Basigin) were measured and compared for clinical pregnancy rates.

RESULTS

Follicular levels of BMP 4 was significantly higher whereas Emmprin levels were lower in patients who had achieved clinically diagnosed pregnancy compared with those who did not achieve clinical pregnancy after ICSI procedure (P = 0.007 and P = 0.035, respectively). BMP 2, BMP 7, and GDF 9 levels were comparable for both groups.

CONCLUSION

Clinical pregnancy rates after ICSI may be associated with follicular fluid levels of Emmprin and BMP 4. Follicular levels of Emmprin and BMP 4 can be used as a marker (as markers for predicting ICSI outcomes) for a better ICSI outcome.

Elevated free fatty acids affect bovine granulosa cell function: a molecular cue for compromised reproduction during negative energy balance

High-yielding dairy cows postpartum face the challenge of negative energy balance leading to elevated free fatty acids levels in the serum and follicular fluid thus affecting the ovarian function. Here, we investigated effects of physiological concentrations of palmitic acid (PA), stearic acid (SA) and oleic acid (OA) on the viability, steroid production and gene expression in a bovine granulosa cell (GC) culture model. Treatment with individual and combined fatty acids increased the CD36 gene expression, while no significant apoptotic effects were observed. Both PA and SA significantly upregulated the expression of FSHR, LHCGR, CYP19A1, HSD3B1, CCND2 and increased 17β-estradiol (E2) production, while OA downregulated the expression of these genes and reduced E2. Interestingly, STAR was equally downregulated by all fatty acids and combination treatment. E2 was significantly reduced after combination treatment. To validate the effects of OA, in vivo growing dominant follicles (10-19 mm) were injected with bovine serum albumin (BSA) with/without conjugated OA. The follicular fluid was recovered 48 h post injection. As in our in vitro model, OA significantly reduced intrafollicular E2 concentrations. In addition, expression of CD36 was significantly up- and that of CYP19A1 and STAR significantly downregulated in antral GC recovered from aspirated follicles. The ovulation rates of OA-injected follicles tended to be reduced. Our results indicate that elevated free fatty acid concentrations specifically target functional key genes in GC both in vitro and in vivo. Suggestively, this could be a possible mechanism through which elevated free fatty acids affect folliculogenesis in dairy cows postpartum.

Understanding mechanisms of oocyte development by follicular fluid lipidomics

PURPOSE

The present study aimed to provide a non-invasive approach to studying mechanisms responsible for oocyte development.

METHODS

To this end, follicular fluid (FF) from 62 patients undergoing in vitro fertilization (IVF) cycles was split into two groups depending on the pregnancy outcome: pregnant (n = 28) and non-pregnant (n = 34) groups. Data were acquired by the MALDI-TOF mass spectrometry. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were applied to the data set. A ROC curve, to predict success rate, was constructed, and the lipids were attributed.

RESULTS

Six ions were differentially represented in FF of pregnant and non-pregnant patients, with an area under the curve of 0.962. Phosphatidic acid, phosphatidylglycerol, and triacylglycerol were hyper-represented in the pregnant group, while glucosylceramide was hyper-represented in the non-pregnant group. Enriched functions related to these lipids are steroidogenesis, cellular response, signal transduction, cell cycle, and activation of protein kinase C for the pregnant group and apoptosis inhibition for the non-pregnant group.

CONCLUSION

Human FF fingerprinting can both improve the understanding concerning mechanisms responsible for oocyte development and its effect on embryo implantation potential and assist in the management of IVF cycles.

Association between pre-breeding metabolic profiles and reproductive performance in heifers and lactating dairy cows

Lactating cows and nulliparous heifers are in distinctive and unique physiological conditions when they are approaching the planned time of breeding, at approximately 60 days in milk and 13-15 months of age, respectively. This study aimed to profile the metabolic milieu in heifers (N = 14) and lactating cows (N = 15) in the weeks leading up to planned time of breeding. All cows were followed for a period of 15 weeks, from 3 weeks pre-calving to 12 weeks post-calving, while heifers were monitored for a period of 4 weeks leading up to the tentative week of breeding (pre-breeding period). For data analysis, we further divided cows into primiparous (N = 8) and multiparous (N = 7) cows owing to the significant difference in their milk yield. Assessment of reproductive performance showed that primiparous and multiparous cows tended to have lower pregnancy rates compared to heifers (P < 0.1). Plasma concentrations of β-hydroxybutyric acid were about 2-fold higher in multiparous cows than those of heifers in the week leading up to planned time of breeding (P < 0.05). Total bile acid levels during the pre-breeding period were higher in all lactating cows compared to heifers (P < 0.05) and glucose levels were lower in lactating cows (P < 0.05). Triglyceride concentrations were lowest in multiparous cows compared to both primiparous cows and nulliparous heifers (P < 0.05). In addition, lactating cows had higher concentrations of total-cholesterol and the high-density lipoprotein and low-density lipoprotein compared to heifers (P < 0.05). Conversely, concentrations of very low-density lipoprotein were lower in multiparous cows than primiparous cows and nulliparous heifers (P < 0.05). There were no differences in plasma glutathione levels, as measured by liquid chromatography-tandem mass spectrometry, between the groups, but the ferric reducing ability of plasma was higher in lactating cows compared to heifers (P < 0.05). These data establish the differences in the profile of metabolic and oxidative markers during the period approaching planned time of breeding in lactating cows compared to nulliparous heifers. As certain metabolites in the plasma have been shown to be represented in the ovarian follicular microenvironment, the unique profiles may influence reproductive performance in dairy cattle in different physiological stages.

Extended lactation in high-yielding dairy cows. I. Effects on reproductive measurements

The objective of this prospective field study was to evaluate the effects of extending the lactation period on various reproductive measurements of high-yielding Holstein cows. On 40 d in milk (DIM), cows were gynecologically examined (transrectal palpation, sonography, vaginoscopy). Cows without signs of clinical endometritis were blocked by parity and were randomly allocated to 1 of 3 experimental groups with a voluntary waiting period (VWP) of 40, 120, and 180 d, respectively (G40, n = 135; G120, n = 141; G180, n = 139). Cows of G120 and G180 were reexamined at the end of the VWP. If natural estrus was detected within 46 d after the end of the VWP, an artificial insemination was performed. If no estrus was detected, the respective cows were synchronized by applying the classical Ovsynch protocol. We found no difference in the proportion of cows in which estrus was detected between 40 to 86 DIM or in the days to first estrus between the 3 groups. Estrus detection in this period was lower in cows with body condition score <3 on 90 DIM compared with body condition score ≥3 (61.5 vs. 76.0%) and in cows with high energy-corrected milk production (ECM) on 92 DIM [58.6 vs. 70.1%, for cows with higher and lower than the median (39.9 kg) ECM, respectively]. The proportion of cows that estrus was detected within 46 d after the VWP was greater in G120 (88.9%) and G180 (90.8%) compared with G40 (70.4%). These effects were more apparent in cows with high ECM. The rate of estrus detection and of becoming pregnant in this period was greater for G120 (hazard ratio = 2.2 and 1.6, respectively) and for G180 (hazard ratio = 2.4 and 1.8) compared with G40. Cows in both groups with extended lactation had greater overall first service conception rates (G120 = 48.9%; G180 = 49.6%) and a lower number of services per pregnant cow (G120 = 1.56 ± 0.1; G180 = 1.51 ± 0.1) compared with G40 (36.6%; 1.77 ± 0.1). We observed no difference in pregnancy loss or in the proportion of cows culled up to 305 d of lactation between the 3 groups. The number of Ovsynch protocols per 1,000,000 kg of ECM was reduced by 75% in G180 and by 74% in G120 compared with G40 (5.9 vs. 7.1 vs. 25.1). In conclusion, extending the lactation of dairy cows can improve main reproductive measurements in high-yielding cows.

Metabolic gene expression and epigenetic effects of the ketone body β-hydroxybutyrate on H3K9ac in bovine cells, oocytes and embryos

The rapid decline in fertility that has been occurring to high-producing dairy cows in the past 50 years seems to be associated with metabolic disturbances such as ketosis, supporting the need for research to improve our understanding of the relations among the diet, metabolism and embryonic development. Recently, the ketone body β-hydroxybutyrate (BOHB) was demonstrated to be a potent inhibitor of histone deacetylases (HDACs). Herein, we performed a series of experiments aiming to investigate the epigenetic effects of BOHB on histone acetylation in somatic cells, cumulus-oocyte complexes (COCs) and somatic cell nuclear transfer (SCNT) embryos. Treatment with BOHB does not increase histone acetylation in cells but stimulates genes associated with ketolysis and master regulators of metabolism. We further demonstrated that maturing COCs with high levels of BOHB does not affect their maturation rate or histone acetylation but increases the expression of PPARA in cumulus cells. Treatment of somatic cell nuclear transfer zygotes with BOHB causes hyperacetylation, which is maintained until the blastocyst stage, causing enhanced FOXO3A expression and blastocyst production. Our data shed light on the epigenetic mechanisms caused by BOHB in bovine cells and embryos and provide a better understanding of the connection between nutrition and reproduction.

Salivary and urinary metabolome analysis for pre-puberty-related biomarkers identification in porcine

Estrus synchronization is important for optimal management of gilt reproduction in pig farms. Hormonal treatments, such as synthetic progestogens, are used on a routine basis, but there is a growing demand for non-hormonal alternative breeding tools. Before puberty, gilts exhibit a ‘waiting period,’ related to the ovarian development and gonadotrophin secretions, during which external stimulations, such as boar exposure, could induce and synchronize first ovulation. Practical non-invasive tools for identification of this period in farms are lacking. During this period, urinary oestrone levels are high, but urine sampling is difficult in group-housed females. The aim of this work was to search for specific biomarkers of the ‘waiting period’ in saliva and urine. In total, nine 144- to 147-day-old Large White gilts were subjected to trans-abdominal ultrasonography three times a week for 5 weeks until puberty detection (week –5 to week –1 before puberty). Urine and saliva samples were collected for oestrone assay to detect the ‘waiting period’ and for metabolome analysis using ¹H-nuclear magnetic resonance spectroscopy to detect potential biomarkers of the ‘waiting period.’ Gilts were slaughtered 7 days after puberty detection for puberty confirmation. Results were consistent with ultrasonography data for six gilts. Urine and saliva samples from these six gilts were analyzed. Urinary estrone concentration significantly increased 2 weeks before puberty detection. Metabolome analysis of urine samples allowed the identification of 78 spectral bins, among them, 42 low-molecular-weight metabolites were identified. Metabolome analysis of salivary samples allowed the identification of 59 spectral bins, among them, 23 low-molecular-weight metabolites were detected and 17 were identified. No potential biomarker was identified in urinary samples. In saliva, butyrate and 2HOvalerate, 5.79 ppm (putatively uridine), formate, malonate and propionate could be biomarker candidates to ascertain the pre-puberty period in gilt reproduction. These results confirm that non-invasive salivary samples could allow the identification of the physiological status of the gilts and presumably the optimal time for application of the boar effect. This could contribute to synchronize puberty onset and hence to develop non-hormonal breeding tools.

Oral propylene glycol modifies follicular fluid and gene expression profiles in cumulus-oocyte complexes and embryos in feed-restricted heifers

Dietary supplementation with propylene glycol (PG) increases in vitro production of high-quality embryos in feed-restricted heifers. The aim of the present study was to evaluate the effects of PG in feed-restricted heifers on follicular fluid insulin and insulin-like growth factor (IGF) 1 concentrations, expression of IGF system genes in oocytes and cumulus cells and the expression of selected genes in blastocysts. Feed-restricted (R) heifers were drenched with water or PG during induced oestrous cycles (400mL of PG or water/drench, daily drenching at 1600 hours for the first 9 days of the oestrous cycle). Ovum pick-up (OPU) was performed after superovulation to produce in vitro embryos and without superovulation to recover oocytes, cumulus cells and follicular fluid. OPU was also performed in a control group (not feed restricted and no drenching). Follicular fluid IGF1 concentrations were reduced by R, and PG restored IGF1 concentrations to those seen in the control group. In cumulus cells, expression of IGF1, IGF1 receptor (IGF1R) and IGF binding protein 4 (IGFBP4) was decreased in the R group, and fully (IGF1 and IGF1R) or partially (IGFBP4) restored to control levels by PG. Blastocyst perilipin 2 (PLIN2; also known as adipophilin), Bcl-2-associated X protein (BAX), SCL2A1 (facilitated glucose/fructose transporter GLUT1), aquaporin 3 (AQP3), DNA (cytosine-5)-methyltransferase 3A (DNMT3A) and heat shock 70-kDa protein 9 (HSPA9B) expression were decreased in R heifers; PG restored the expression of the last four genes to control levels. In conclusion, these results suggest that, during follicular growth, PG exerts epigenetic regulatory effects on gene expression in blastocyst stage embryos.

Effect of nutritionally induced hyperlipidaemia on in vitro bovine embryo quality depends on the type of major fatty acid in the diet

The present study examined whether the effects of dietary-induced hyperlipidaemia on preimplantation embryo development depend on the predominant fatty acid (FA) type in the diet. In a combined in vivo-in vitro bovine model, two groups of cows (n=3 in each group) were fed with three diets consecutively (4 weeks feeding for each): (1) a maintenance control diet (CONT); (2) a high-starch diet rich in saturated fat (SAT); and (3) a high-starch diet rich in omega-3 unsaturated fat (UNSAT). Two feeding sequences were used to test for carry-over effects: Group A was fed CONT, SAT1 and then UNSAT2, whereas Group B was fed CONT, UNSAT1 and then SAT2. Serum was collected after each dietary period, analysed and tested in bovine in vitro embryo culture. Introducing SAT and UNSAT diets induced hyperlipidaemia (specifically hypercholesterolaemia and elevated free FAs) and reduced insulin sensitivity. Carry-over effects in serum metabolites and FA profile were dependent on the diet and feeding sequence. SAT1 and SAT2 serum decreased blastocyst rates and altered blastocyst mRNA expression related to apoptosis and oxidative stress. UNSAT1 and UNSAT2 serum resulted in normal embryo development and quality. Other in vitro effects depended on the sequence of feeding. In conclusion, substitution of saturated fat with omega-3 fat in a high-caloric diet induced hyperlipidaemia with an FA profile yielding similar rates and quality of blastocysts compared with normolipidaemic controls.

Nutritional and metabolic stressors on ovine oocyte development and granulosa cell functions in vitro

The present study was undertaken to study the effect of ammonia, urea, non-esterified fatty acid (NEFA), and β-hydroxybutyric acid (β-OHB) on oocyte development and granulosa cell (GC) growth parameter of ovine (Ovis aries). Ovine oocytes were matured in vitro in the presence of different concentration of ammonia, urea, NEFA, and β-OHB for 24 h, in vitro inseminated and evaluated for cleavage and blastocyst yield. Same concentrations of ammonia, urea, NEFA, and β-OHB were examined on growth parameters and hormone secretion activity of granulosa cells in vitro. Real-time reverse transcription polymerase chain reaction was used to evaluate the expression of steroidogenic genes (steroidogenic cytochrome P-450 (CYP11A1, CYP19A1)), cell proliferation-related genes (GDF9, FSHr), and apoptosis-related genes (BCL-2 and BAX). The maturation, cleavage, and blastocyst production rates were significantly lowered in media containing either 200 μM ammonia or 5 mM urea or high combo NEFA or 1 μM β-OHB. Exposure of granulosa cell to 400 μM ammonia or 1 μM β-OHB or very high combo or 6 mM urea significantly decreased all the parameters examined compared to lower levels of all nutritional and metabolic stressors. Elevated concentration of metabolic stressors induced GC apoptosis through the BAX/BCL-2 pathway and reduced the steroidogenic gene messenger RNA (mRNA) expression and cell proliferation gene mRNA expression. These results suggested that the decreased function of GCs may cause ovarian dysfunction and offered an improved understanding of the molecular mechanism responsible for the low fertility in metabolic stressed condition.

Lactation-induced changes in metabolic status and follicular-fluid metabolomic profile in postpartum dairy cows

The aim was to investigate the effect of lactation on the composition of pre-ovulatory follicular fluid (FF). Forty in-calf primiparous heifers and 20 maiden heifers were enrolled. Immediately after calving, half of the cows were dried off while the remainder were milked twice daily. Serum samples were collected twice weekly from two weeks pre- to 84 days postpartum (dpp). FF was analysed by gas chromatography-mass spectrometry. Serum concentrations of non-esterified fatty acids and β-hydroxybutyrate were higher, while glucose, insulin and Insulin-like growth factor 1 (IGF1) concentrations were lower in lactating cows compared with non-lactating cows and heifers (P<0.01). Principal component analysis of FF metabolites revealed a clear separation of the lactating group from both non-lactating cows and heifers. The amino acids tyrosine, phenylalanine and valine and fatty acids heneicosanoic acid and docosahexaenoic acid were all lower in FF from lactating compared with dry cows (P<0.05). FF from lactating cows was higher in aminoadipic acid, α-aminobutyric acid, glycine and serine while histidine, leucine, lysine, methionine and ornithine were all lower than in dry cows and heifers (P<0.05). The ratio of n6:n3 was higher in lactating cows compared with both non-lactating cows and heifers, whereas total n3 polyunsaturated fatty acids, pentadecanoic, linolenic, elaidic and arachidonic acids were all lower in the FF of lactating cows than both non-lactating cows and heifers (P<0.05). In conclusion, lactation induces distinct changes in the overall metabolic status of postpartum lactating dairy cows which are associated with divergent metabolite profiles in FF.