The effect of an acute energy deficit on the hormone profile of dominant follicles in dairy cows

Hepatic Lipidosis in Ruminants

Hepatic lipidosis (ie, fatty liver) occurs primarily during the first weeks of lactation in dairy cows because of excessive lipolysis overwhelming the concomitant capacity for beta-oxidation and hepatic export of triglycerides. Besides economic losses due to reduced lactational and reproductive performance, close associations with concomitantly occurring infectious and metabolic health disorders, in particular ketosis, exist. Hepatic lipidosis is not only a consequence from the postpartal negative energy balance but also acts as a disease component for further health disorders.

Comparison of Metabolic Alterations in Serum and Milk Whey Between Inactive Ovaries and Estrus Dairy Cows

Inactive ovaries (IOs) affect the estrus cycle and timed artificial insemination (TAI) efficiency in dairy cows during early lactation. The objective of the experiment was to determine metabolic changes in the serum and milk whey of dairy cows with IO and estrus. Twenty-eight healthy postpartum Holstein cows in similar age, milk production, and body condition were selected at 30 days postpartum for tracking to 70 days postpartum, and estrus performance was recorded through Afi Farm® software. The ovarian status and follicular diameter of dairy cows were examined by an experienced breeder through B-ultrasound and rectal examination. Fourteen normal estrus cows were allocated to control group A and 14 cows with IO to group B, all at 30–70 days postpartum. The serum and milk whey in the two groups of cows at 70 days postpartum were used for non-targeted nuclear magnetic resonance (¹H-NMR) analysis to measure the different metabolites of cows with IO. In group B compared with group A at 70 days postpartum, there was an increase in the milk whey of six different metabolites including succinate, creatine phosphate, glycine, myo-inositol, glycolate, and orotate and a decrease in the milk whey of seven metabolites, including alanine, creatinine, o-phosphorylcholine, lactose, taurine, galactose, and glucose-1-phosphate. There was an increase in the serum of group B cows of four differential metabolites, including 3-hydroxybutyrate, acetate, glutamine, and glycine and a decrease in the serum of nine differential metabolites, including alanine, succinate, citrate, creatinine, o-phosphocholine, glucose, myo-inositol, tyrosine, and histidine compared with group A. Group B cows with IO had decreased glucose metabolism and impaired tricarboxylic acid cycle, increased lipid mobilization, and abnormal amino acid metabolism. The study provides a potential prevention strategy for IO in dairy cows in future.

Luteal activity and effect of dietary energy restriction on follicular development in lactating cows

The aim of this research has been to evaluate the presence of anomalies in the ovarian cycle activity during postpartum and to verify whether 72-hr dietary fasting during the dominance phase, the phase before ovulation, might modify the ovarian follicle population. The presence of anomalies in ovarian cycle activity has been evaluated in 30 Italian Friesian cows starting from 20 days postpartum until 211 days of lactation. Long oestrus and brief dioestrus or scarce luteal activity have been the main anomalies found through measuring progesterone concentrations in the whey. Until 100 days of lactation, the BCS values of the problematic animals have been significantly lower than those in animals with normal ovarian activity. After 100 days of lactation, the ovarian anomalies continued to appear despite the fact that all the animals have reached comparable BCS values. Starting from the results of this trial, the effect of 72-hr dietary fasting on dominant follicles has been studied in six cows. Ultrasonography revealed that the diameter of the follicles at 71 days postpartum has been significantly lower than at 181 days. A 72-hr dietary restriction at 101 and 211 days postpartum did not affect the size of the dominant follicle. However, at 101 days postpartum, half of the animals presented follicular cysts. The effect of fasting differed if the animal has been in early postpartum or 211 days of lactation. Further researches are necessary to understand how different metabolic conditions can modify the follicular population but on the other hand the study shows the utility for farmers and field veterinarians of monitoring the resumption of the ovarian cycle postpartum through the whey progesterone concentrations.

Postpartum hormone and energy profiles and their influence on the resumption of ovarian cyclicity in Curraleiro Pé-Duro cows

The objective of this study was to evaluate hormone and energy profiles in the postpartum period and to correlate these profiles with the resumption of ovarian cyclicity, as well as characterizing the postpartum short estrous cycle of Curraleiro Pé-Duro cows. Twelve Curraleiro Pé-Duro cows were examined via rectal palpation and ultrasound at 10 days postpartum, and subsequently examined daily to evaluate the resumption of ovarian cyclicity as well as every five days in order to evaluate uterine involution. Upon analysis of the data, it was possible to observe the formation of two distinct groups, one of which was comprised of those animals which returned to cyclicity within 60 days postpartum and another comprised of those animals which returned to cyclicity more than 105 days postpartum. Therefore, animals were divided into two groups; precocious, designated Ov Group, and delayed, designated NOv Group, wherein the cut-off time for all tests was 60 days postpartum. Statistically significant differences (P < 0.01) between the groups occurred only regarding the day of 1st ovulation, which in the Ov Group averaged 51.4 ± 9.3 days and in the NOv Group averaged 138.3 ± 19.8 days postpartum. The other postpartum short estrous cycle variables assessed did not show statistically significant differences (P > 0.05) between the groups. NEFA, BHBA and thyroxine concentration levels did not differ (P > 0.05) between the groups in any of the statistical analyses. However, in the analysis comparing growth curves, triglycerides levels were higher for the Ov Group (P = 0.04) and cholesterol levels were higher for the NOv Group (P = 0.02). In this experiment, a small influence of a negative energy balance between the groups was observed, suggesting that these animals can present significant genetic variability due to natural selection, as evidenced by the formation of groups of animals with precocious and delayed reproductive characteristics.

The effect of a negative energy balance status on β-carotene availability in serum and follicular fluid of nonlactating dairy cows

Maternal metabolic pressure due to a cow's negative energy balance (NEB) has a negative effect on oocyte quality as a result of increased oxidative stress. In this study, we hypothesized that a NEB status may negatively affect the availability of β-carotene (bC, an antioxidant) in the micro-environment of the oocyte or follicular fluid (FF) and that daily bC supplementation can increase bC availability. We aimed to (1) determine the effect of a nutritionally induced NEB on bC concentrations in serum and FF as well as on the presence of bC metabolites, oxidative stress levels, and follicular growth in a nonlactating dairy cow model, and (2) investigate how this effect could be altered by dietary bC supplementation. Six multiparous nonlactating Holstein Friesian cows were subjected to 4 consecutive dietary treatments, 28 d each: (1) 1.2 × maintenance (M) or positive energy balance (PEB) without bC supplement (PEB-bC), (2) 1.2 × M with daily supplement of 2,000mg of bC comparable to the level of bC intake at grazing (PEB+bC), (3) 0.6 × M with 2,000mg of bC (NEB+bC), and (4) 0.6 × M (NEB-bC). At the end of each treatment, estrous cycles were synchronized and blood and FF of the largest follicle were sampled and analyzed for bC, retinol, α-tocopherol, free fatty acids, estradiol, and progesterone. Serum cholesterol, triglycerides, urea, insulin growth factor 1, growth hormone, total antioxidant status (TAS), and red blood cell glutathione (GSH) concentrations were determined as well. All cows lost body weight during both energy restriction periods and showed increased serum free fatty acid concentrations, illustrating a NEB. A dietary induced NEB reduced FF bC, but not plasma bC or plasma and FF retinol concentrations. However, bC and retinol concentrations drastically increased in both fluid compartments after bC supplementation. Follicular diameter was increased in supplemented PEB cows. Energy restriction reduced the TAS and red blood cell GSH, whereas daily bC supplementation could restore GSH concentrations, but not the TAS, to levels present in healthy PEB cows. In conclusion, daily bC supplementation can substantially improve bC and retinol availability in the oocyte's micro-environment, irrespective of the energy balance, which may affect follicular development and oocyte quality in the presence of maternal metabolic stress. This knowledge can be of importance to optimize nutritional strategies in the dairy industry to feed for optimal oocyte quality and fertility.

Impact of maternal malnutrition during the periconceptional period on mammalian preimplantation embryo development

During episodes of undernutrition and overnutrition the mammalian preimplantation embryo undergoes molecular and metabolic adaptations to cope with nutrient deficits or excesses. Maternal adaptations also take place to keep a nutritional microenvironment favorable for oocyte development and embryo formation. This maternal-embryo communication takes place via several nutritional mediators. Although adaptive responses to malnutrition by both the mother and the embryo may ensure blastocyst formation, the resultant quality of the embryo can be compromised, leading to early pregnancy failure. Still, studies have shown that, although early embryonic mortality can be induced during malnutrition, the preimplantation embryo possesses an enormous plasticity that allows it to implant and achieve a full-term pregnancy under nutritional stress, even in extreme cases of malnutrition. This developmental strategy, however, may come with a price, as shown by the adverse developmental programming induced by even subtle nutritional challenges exerted exclusively during folliculogenesis and the preimplantation period, resulting in offspring with a higher risk of developing deleterious phenotypes in adulthood. Overall, current evidence indicates that malnutrition during the periconceptional period can induce cellular and molecular alterations in preimplantation embryos with repercussions for fertility and postnatal health.

Dietary fat supplementation and the consequences for oocyte and embryo quality: hype or significant benefit for dairy cow reproduction?

In many countries, fat supplementation in the diet has become common in the dairy industry. There are several ideas as to how dietary fat could influence reproductive performance. Saturated fatty acids, such as palm oil, can increase milk yield but may aggravate negative energy balance and thus may impair fertility when fed during the first week post-partum. However, priming the lipid oxidation in the liver by feeding saturated fats during the dry period has recently been shown to be a potentially promising strategy to mitigate fat mobilization and liver accumulation post-partum. Furthermore, polyunsaturated fats (omega-3 fatty acids and conjugated linoleic acids) are fed to reduce the 'de novo' fat synthesis in the udder and thus the milk fat content, which may be of modest benefit for overall energy balance. Furthermore, omega-6 and omega-3 polyunsaturated fatty acids are reported to alter follicular growth, steroid synthesis and prostaglandin metabolism in the ovary and endometrium, respectively. Omega-6 fatty acids are believed to have pro-inflammatory and thus PGF2α-stimulating properties rendering them extra value as 'nutraceutical' early post-partum, while omega-3 fatty acids can weaken this inflammatory potency, leading to a higher chance of survival of the embryo when supplemented during the periconceptual period. Unfortunately, research results rarely provide a consensus in this perspective. The consequences of these fat-feeding strategies on oocyte and embryo quality remain an intriguing issue for debate. Fat feeding may alter the microenvironment of the growing and maturing oocyte of the early and older embryo and thus may affect reproductive outcome. We recently reported that dietary-induced hyperlipidaemic conditions can be harmful for embryo development and metabolism. However, to date, research results remain somewhat conflicting most probably due to differences in fat sources used, in diet and duration of supplementation and in experimental set-up in general.

The consequences of metabolic changes in high-yielding dairy cows on oocyte and embryo quality

Unsatisfactory reproductive performance in dairy cows, such as reduced conception rates, in addition to an increased incidence of early embryonic mortality, is reported worldwide and has been associated with a period of negative energy balance (NEB) early post partum. Typically, NEB is associated with biochemical changes such as high non-esterified fatty acid (NEFA), high β-hydroxybutyrate (β-OHB) and low glucose concentrations. The concentrations of these and other metabolites in the follicular fluid (FF) of high-yielding dairy cows during NEB were determined and extensively analyzed, and then were replicated in in vitro maturation models to investigate their effect on oocyte quality. The results showed that typical metabolic changes during NEB are well reflected in the FF of the dominant follicle. However, the oocyte seems to be relatively isolated from extremely elevated NEFA or very low glucose concentrations in the blood. Nevertheless, the in vitro maturation models revealed that NEB-associated high NEFA and low glucose levels in the FF are indeed toxic to the oocyte, resulting in deficient oocyte maturation and developmental competence. Induced apoptosis and necrosis in the cumulus cells was particularly obvious. Furthermore, maturation in saturated free fatty acid-rich media had a carry-over effect on embryo quality, leading to reduced cryotolerance of day 7 embryos. Only β-OHB showed an additive toxic effect in moderately hypoglycemic maturation conditions. These in vitro maturation models, based on in vivo observations, suggest that a period of NEB may hamper the fertility of high-yielding dairy cows through increased NEFA and decreased glucose concentrations in the FF directly affecting oocyte quality. In addition to oocyte quality, these results also demonstrate that embryo quality is reduced following an NEB episode. This important observation may be linked to the typical diet provided to stimulate milk yield, or to physiological adaptations sustaining the high milk production. Research into this phenomenon is ongoing.

Acute dietary restriction in heifers alters expression of genes regulating exposure and response to gonadotrophins and IGF in dominant follicles

Dietary restriction in growing cattle and severe negative energy balance in lactating cows have been associated with altered gonadotropin secretion, reduced follicle diameter, reduced circulating oestradiol concentrations and anovulation. Therefore, we hypothesised that acute dietary restriction would influence the fate and function of the dominant follicle by altering the expression for genes regulating gonadotrophin and IGF response in ovarian follicles. Newly selected dominant follicles were collected 7-8 days after prostaglandin F(2α) (PGF) administration from heifers (n=25) that were individually fed a diet supplying 1.2 maintenance (M; control, n=8) or 0.4 M (restricted, n=17) for a total duration of 18-19 days. Heifers within 0.4 M were ovulatory (n=11) or anovulatory (n=6) depending on whether the dominant follicle present at PGF ovulated or became atretic following luteolysis. Control animals were all ovulatory. Acute dietary restriction decreased IGF-I (P<0.001) and insulin (P<0.05) in circulation; oestradiol (P<0.01) and IGF-I (P<0.01) in follicular fluid; and mRNA for FSHR (P<0.01) in granulosa cells but increased mRNA for IGFBP2 (P<0.05) in theca cells of the newly selected dominant follicle. However, this only led to anovulation when dietary restriction also decreased mRNA for CYP19A1 (P<0.05), IGF2 (P<0.01) and IGF1R (P<0.05) in granulosa cells and LHCGR (P<0.05) in theca cells of follicles collected from heifers fed 0.4 M. These results suggest that the catabolic environment induced by dietary restriction may ultimately cause anovulation by reducing oestradiol synthesis, FSH-responsiveness and IGF signaling in granulosa, and LH-responsiveness in theca cells of dominant follicles.

Intrafollicular conditions as a major link between maternal metabolism and oocyte quality: a focus on dairy cow fertility

Reduced oocyte and embryo quality are recognised as major factors in the problem of disappointing fertility in high producing dairy cows. This review aims to shed more light on the importance of the intrafollicular environment in the subfertility problem in dairy cows. Metabolic disturbances associated with negative energy balance (NEB) early postpartum are associated with ovarian dysfunction. Changes in the growth pattern of the ovarian follicle during a period of NEB can indirectly affect oocyte quality. Furthermore, a maternal metabolic disorder (linked with NEB or nutritionally induced) may alter the endocrine and biochemical composition of the follicular fluid, the micro-environment of the growing and maturing female gamete. The maturing oocyte is very sensitive to any perturbation in its direct environment and in vitro maturation models revealed that some of these metabolic changes reduce the oocyte’s developmental competence. Also, embryo quality is significantly reduced due to maturation in adverse conditions. Well balanced and timed oocyte metabolism and gene expression are crucial to safeguard an optimal oocyte development. In that perspective, metabolome and transcriptome parameters of the oocyte may serve to predict reproductive success rates. Finally, there is growing evidence that adverse conditions for oocyte growth and maturation may also jeopardise the health and performance of the offspring.

Effects of high dietary crude protein on the characteristics of preovulatory follicles in dairy heifers

The objectives were to examine the effect of high dietary crude protein on characteristics of preovulatory follicles in dairy heifers. Eight Israeli-Holstein heifers, 4 fitted with rumen fistula and 4 intact, were assigned to 1 of 3 treatments in a replicated (n=2) 4 × 3 incomplete Latin square design with 39-d periods. Treatments were: low (6.0%; LP), moderate (13.0%; MP), and high (20.0%; HP) crude-protein diets, containing 1.27 Mcal NE(L)/kg dry matter. Diets were based on approximately 66% wheat straw and various proportions of ground corn grain and soybean meal. The estrous cycles of the heifers were synchronized, and 14 d after behavioral estrus, heifers received PGF(2 α) injections. After a further 40 h, at d 39 of each period, follicular fluid (FF) was aspirated from follicles of diameter >7 mm. The intake of the LP diet was 9% lower than that of MP and HP diets. Rumen ammonia and plasma urea nitrogen concentrations were highest in the HP and lowest in the LP, with intermediate levels in MP diets. No differences were found between treatments in plasma and FF concentrations of glucose and nonesterified fatty acids. High-protein diets increased urea concentrations very similarly in preovulatory FF and in plasma. No differences were observed between diets, in preovulatory follicle diameters and concentrations of androstenedione. However, higher estradiol and progesterone concentrations in FF were observed under the HP than under the MP diet, with no difference between diets in estrogen to progesterone ratio. It can be concluded that high concentrations of urea in plasma, caused by high dietary crude protein, penetrated into preovulatory follicles, but did not impair preovulatory characteristics. This lack of detrimental effects might be attributed to the use in this study of nonlactating heifers, which have fewer nutritional and physiological constraints and eliminate negative effects of potential interactions with high urea on dairy cows' reproductive systems.

Reduced fertility in high-yielding dairy cows: are the oocyte and embryo in danger? Part I. The importance of negative energy balance and altered corpus luteum function to the reduction of oocyte and embryo quality in high-yielding dairy cows

Fertility in high yielding dairy cows is declining, and there is increasing evidence to presume that oocyte and embryo quality are major factors in the complex pathogenesis of reproductive failure. In this report we present an overview of possible mechanisms linking negative energy balance (NEB) and deficiencies in oocyte and embryo developmental competence; specifically, in the high producing dairy cow. Changes in follicular growth patterns during a period of NEB can indirectly affect oocyte quality. The endocrine and biochemical changes, which are associated with NEB, are reflected in the microenvironment of the growing and maturing female gamete, and likely result in the ovulation of a developmentally incompetent oocyte. Even after an oocyte is successfully ovulated and fertilized, a full-term pregnancy is still not guaranteed. Inadequate corpus luteum function, associated with reduced progesterone, and probably also low insulin-like growth factor concentrations, can cause a suboptimal microenvironment in the uterus that is incapable of sustaining early embryonic life. This may partly account for the low conception rates and the high incidence of early embryonic mortality in high yielding dairy cows.

Estrogen to progesterone ratio affects hormonal and lipid follicular fluid profiles in dairy cows

Aim:  The present study described hormonal and lipids concentrations of follicles that develop under high progesterone plasmatic levels, mimicking the second follicular wave. Methods:  All follicles were removed by aspiration in order to generate a new follicular wave. Follicular fluid was then obtained from either 3 day old follicles (F3) or 6 day old follicles (F6). This experimental protocol was carried out at 20 days and 90 days post-partum on Frisian dairy cows that had already returned to cyclicity. Results:  Estrogen active follicles (ratio of estrogen to progesterone in follicular fluid higher than 1) have higher levels of VEGF, IGF-I and linoleic acid, and have lower levels of NEFA, oleic and arachidonic acid. Non-estrogen active follicular fluid concentrations of IGF-I and NEFA were similar to plasma concentrations. In contrast, estrogen active follicles showed higher IGF-I and lower NEFA levels than plasmatic ones that could be used to sustain follicular growth. Conclusions:  The results show that estrogen active follicles might have their own metabolism. (Reprod Med Biol 2007; 6: 45-51).

Hormonal and metabolic adaptation to fasting: effects on the hypothalamic-pituitary-ovarian axis and reproductive performance of rabbit does

To assess the impact of acute caloric shortage on reproduction, rabbit does were either fed ad libitum (control, AL), or fasted for 24 (STF) or 48 h (LTF) before induction of ovulation with GnRH injection. Blood samples were collected during the last 3 h of fasting, and the following 4 h after GnRH injection, when feed was provided again, to measure plasma concentrations of LH, estradiol-17beta, leptin, insulin, T3, corticosterone, glucose, and NEFA. Before re-feeding, plasma leptin, insulin, and T3 concentrations were lower (P < or = 0.01) in both fasted groups than in controls, but then gradually increased following realimentation to match those of controls. During fasting, corticosterone levels were higher (P < or = 0.01) in LTF than in STF and AL does, but decreased to control values soon after realimentation. During fasting, plasma glucose concentrations did not differ among groups, but upon re-feeding they markedly increased (P < or= 0.01) both in STF and LTF does. NEFA levels were also more elevated (P < or = 0.01) in fasted rabbits than in controls, and rapidly decreased (P < or = 0.01) after re-feeding. Following GnRH injection, LH peak was lower (P < or = 0.01) in LTF than in AL and STF does. Estradiol-17beta showed higher pulse frequency and amplitude in AL than in STF and LTF does. Compared to controls, receptivity rate of STF and LTF artificially inseminated does declined respectively by -20.5% (P < or = 0.05) and -22.7%, and fertility rate by -23.9% (P < or = 0.05) and 21.4%, but no difference was found in ovulation rate. In summary, nutritional status of does, as modified by fasting, greatly influenced fertility, metabolic and reproductive hormones.

Effect of non-esterified fatty acids on bovine theca cell steroidogenesis and proliferation in vitro

Elevated serum non-esterified fatty acid (NEFA) levels associated with a negative energy balance (NEB) may affect ovarian function and hence reproductive performance in high-yielding dairy cows. We have investigated the individual and combined effects of the three major NEFAs on bovine theca cell proliferation and steroidogenesis in vitro. Theca cells from healthy large follicles (>8 mm) obtained from slaughterhouse ovaries were cultured in serum free medium in the presence of 0, 50, 150 and 200 microM of palmitic acid (PA; C16:0); 0, 50, 150 and 250 microM of stearic acid (SA; C18:0); and/or 0, 50, 150 and 250 microM of oleic acid (OA; C18:1). Progesterone and androstenedione concentrations were measured in spent medium after 48 h of culture and cell numbers were determined spectrophotometrically per culture well. Cell viability was assessed by annexin-V FITC/propidium iodide staining. Only the treatment with 200 microM of PA inhibited cell proliferation (P<0.001) when tested individually, both of the mixtures tested (M1=100 microM of PA, 130 microM of SA and 140 microM of OA; M2=200 microM PA, 260 microM of SA and 280 microM of OA) reduced cell numbers (P<0.001). Progesterone and androstenedione production, both per well and per 10(4) cells, were not affected by any of the treatments, with the exception of M2. This mixture reduced progesterone production per well and per 10(4) cells (P<0.05). The effects observed were most likely caused by the cytotoxic action of the NEFAs, as demonstrated by the increased percentage of early apoptotic (M1) and late apoptotic/necrotic cells (M1 and M2) in the combination treatments (P<0.05). When combined, elevated physiological concentrations of PA, SA and OA can modulate theca cell proliferation and steroidogenesis in vitro by reducing theca cell viability. These NEFAs may be one of the mediators through which NEB compromises ovarian functioning and thus fertility in high-yielding dairy cows.

Invited review: pathology, etiology, prevention, and treatment of fatty liver in dairy cows

Fatty liver (i.e., hepatic lipidosis) is a major metabolic disorder of many dairy cows in early lactation and is associated with decreased health status and reproductive performance. In severe cases, milk production and feed intake are decreased. Therefore, a practical preventative or an efficacious treatment of fatty liver could save millions of dollars yearly in treatment, replacement, and production losses for dairy farmers. Fatty liver develops when the hepatic uptake of lipids exceeds the oxidation and secretion of lipids by the liver, which usually is preceded by high concentrations of plasma NEFA mobilized from adipose tissue. Excess lipids are stored as triacylglycerol in the liver and are associated with decreased metabolic functions of the liver. Liver can be categorized into normal liver or mild, moderate, or severe fatty liver; the latter can be subdivided further into nonencephalopathic severe fatty liver and hepatic encephalopathy. Insufficient or unbalanced dietary intake, obesity, and elevated estrogen concentrations are involved in the etiology of fatty liver, which is associated with greater incidence of dystocia, diseases, infections, and inflammations. Because even mild fatty liver is associated with decreased health status and reproductive performance of dairy cows, prevention of fatty liver by supplying cows with sufficient nutrients and a clean and health-promoting environment in the peripartal period would reduce production losses of cows more than would any treatment of fatty liver. This, however, might not be enough for cows that are obese or do not eat well, had calving difficulties or twins, have metabolic or infectious diseases, or are in severe negative energy balance because of high milk production immediately after calving. Potential and commonly used preventatives, as well as treatments, are discussed in the review. Currently, detection of fatty liver is possible only by minor surgery. Ultrasonic techniques offer a potential tool to noninvasively detect fatty liver. Future gene-array and proteomic studies may provide means to detect early molecular events in the etiology of fatty liver plus their connection with immune function and reproductive performance so that more effective treatments and preventatives of fatty liver can be developed. Such advances hopefully will make fatty liver a problem of the past.

Effect of non-esterified fatty acids on bovine granulosa cell steroidogenesis and proliferation in vitro

In high-yielding dairy cows, the negative energy balance (NEB) during the first weeks post partum may influence dominant follicle growth and steroidogenesis. Since non-esterified fatty acid (NEFA) concentrations are elevated during NEB and are shown to be toxic for several cell types, we investigated the individual and combined effects of the three main NEFA's on granulosa cell proliferation and steroidogenesis in vitro. Granulosa cells from large follicles were cultured for two days in serum free medium in the presence of palmitic (C16:0) (PA), stearic (C18:0) (SA) and/or oleic acid (C18:1) (OA). Addition of 150, 300 or 500 microM of PA and SA inhibited cell proliferation (P<0.05) while OA only elicited such an effect at 500 microM (P<0.01). In the combination treatment (150 microM of each fatty acid), cell numbers were also reduced (P<0.01). These inhibitory effects on cell number are partly due to the induction of apoptosis by these NEFA's, as was demonstrated by annexin V-FITC/propidium iodide staining of the granulosa cells. Oestradiol-17beta production was stimulated by all doses of PA, by 300 and 500 microM of SA and by 500 microM of OA (P<0.05). Combined treatment with 150 microM of each fatty acid also stimulated oestradiol-17beta production per 10(4) cells (P<0.05). We can conclude that PA, SA and to a lesser degree OA modulate granulosa cell proliferation and steroidogenesis in vitro. These effects may be involved in the occurrence of ovarian dysfunction during the postpartum period in high-yielding dairy cows.

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

Characteristics of the intrafollicular environment to which the preovulatory oocyte is exposed may be one of the major factors determining subsequent fertility. The aim of our study was to examine to what extent metabolic changes that occur in early post partum high-yielding dairy cows are reflected in the follicular fluid (FF) of the dominant follicle (>8 mm). Nine blood samples were taken per cow from nine high-yielding dairy cows between 7 days before and 46 days after parturition. From Day 14 post partum on and together with blood sampling, FF samples of the largest follicle were collected from the same cows by means of transvaginal follicle aspiration. Serum and FF samples were analyzed using commercial clinical and photometric chemistry assays for glucose, beta-hydroxybutyrate (beta-OHB), urea, total protein (TP), triglycerides (TG), non-esterified fatty acids (NEFA) and total cholesterol (TC). All cows lost body condition during the experimental period (0.94+/-0.09 points) illustrating a negative energy balance during the experimental period. In FF, glucose concentrations were significantly higher and the TP, TG, NEFA and TC concentrations were significantly lower than in serum (P<0.05). The concentrations of glucose, beta-OHB, urea and TC in serum and in FF changed significantly over time (P<0.05). Throughout the study, changes of all metabolites in serum were reflected by similar changes in FF. Especially for glucose, beta-OHB and urea the correlations were remarkably high. The results from the present study confirm that the typical metabolic adaptations which can be found in serum of high-yielding dairy cows shortly post partum, are reflected in follicular fluid and, therefore, may affect the quality of both the oocyte and the granulosa cells.

Effects of non-esterified fatty acids on bovine granulosa cells and developmental potential of oocytes in vitro

High yielding dairy cows experience a negative energy balance (NEB) shortly after parturition, which is accompanied by high concentrations of non-esterified fatty acids (NEFA) in blood up to approximately 3 weeks post partum. We hypothesized that the elevated plasma NEFA concentration causes lower fertility by exerting negative effects on granulosa cells and oocytes in the ovary, leading to less viable embryos and insufficient corpora lutea. In two series of experiments, we studied the effects of a realistic NEFA (C18:1) concentration on both the proliferation and the progesterone production of follicular granulosa cells in vitro (part I) and on maturation, fertilization and developmental potential of oocytes (part II). For part I, granulosa cells were added to 4 groups of dishes with four different media and cultured for nine consecutive days. After a preculture period of 42h, the presence of NEFA had a negative effect on the proliferation of granulosa cells. No effect of NEFA on the amount of progesterone production per cell was observed. For part II, a total of 1804 cumulus-oocyte-complexes were collected from slaughterhouse ovaries. Using a subgroup of 690 COC, maturation medium with NEFA caused a delay in maturation. Using another 1114 COC, fertilization, cleavage, and embryonic development after maturation in presence of NEFA were significantly reduced. We concluded that the presence of NEFA in follicular fluid and blood of post partum cows may reduce fertility due to hampered embryonic development and subnormal CL function.