Codominant Follicles Research Articles

The effect of different doses of estradiol benzoate on follicle development and twin birth in beef cattle with induced superovulation

Abstract. The aim of this study was to evaluate the effect of different doses of estradiol benzoate (EB) on inhibiting the development of non-dominant follicles and inducing twin calves in beef heifers. Beef heifers were synchronized using estradiol plus progesterone (P4), and superovulation was induced using a small-dose follicle-stimulating hormone (FSH) protocol. From day 6.5 to day 7.5, every heifer was treated with 0, 0.1, 0.2, or 0.5 mg EB three times at 12 h intervals to eliminate excess dominant follicles. The diameters of the two largest follicles (F1 and F2) continually increased from day 3.5 to day 10. However, the growth rate was constrained by exogenous EB, and the degree of suppression was greatest in the 0.5 mg EB treatment compared with other treatments. As a result, the number of large follicles (≥10 mm) decreased as the EB dose increased. Compared with the control treatment, the incidence of animals experiencing triple ovulation was significantly lower in the 0.5 mg EB treatment; however, the single-ovulation rate showed the inverse. This study demonstrated that 0.2 mg EB could modulate the development of two to three co-dominant follicles after a small-dose FSH treatment. The number of twin births was higher in the 0.2 mg EB treatment.

REVIEW ON THE IMPACT AND CONSEQUENCES OF THE OCCURRENCE OF MULTIPLE BIRTHS IN CATTLE AND GOATS

Background: The large animal species such as cattle, buffaloes and horses are monotocous with one or sometimes two newborns per birth whereas small farm animal species such as sheep, goats and pigs are usually polytocous animals are highly prolific and especially pigs often produce a dozen newborns at each farrowing. Cattle usually produce only one calf per gestation resulting from ovulation of a single follicle. The most common form of twinning in cattle occurs due to multiple ovulations which may produce dizygotic twins. The twin births in dairy cattle often negatively impacts the reproduction, production, health and reduces the productive lifespan of cows. Therefore, there is a great interest to know the multiple ovulations and multiple births to reduce the twinning rate in dairy cattle herds. Objective: This review updates the status of multiple births and its impact and consequences on production of dairy cattle and goats. Materials and Methods: The related literatures on the multiple births in cattle and goats have been reviewed for which the search was carried out in Google Scholar, PubMed, CrossRef, Banglajol and also the online daily newspapers. Results: Although multiple births with up to quadruplets have been reported from different countries, the prevalence of twin births are commonly reported in dairy cattle. The prevalence of twinning rates are varied widely in different breeds like twin calving in Holstein Friesian cattle is 3 to 5%, 5.6% Spanish dairy herd and 3.9% in Iranian Holsteins, whereas triplet and quadruplet births represent 0.015% and 0.004% of the total births, respectively. Twin calving shorten gestation length, increased dystocia, stillbirths, decrease birth weight, perinatal calf mortality, retained placenta, decrease milk production, increases the occurrence of metabolic diseases, reduced conception rate, increased calving interval, shorten the productive lifespan of the dam and increases overall culling rate. Two strategies- the transfer of a single embryo produced in vitro and follicular drainage of co-dominant follicles at AI have been suggested to prevent twin pregnancies. Conclusion: Multiple births in dairy cattle is not desirable due to negative effects on both cows that calve twins and calves born as twins that result in economic losses in dairy herds. Regardless of the direct effect of multiple births on health and fertility, reducing the occurrence of multiple ovulations to decrease the risk of twin births is desirable to mitigate the negative consequences of twinning in dairy cattle. The estimated losses due to twinning range between US$ 59 to 161 per twin pregnancy and attempting manual embryo reduction decreased the economic losses of a twin pregnancy by US $ 23 to 45. Bangladesh scientists discovered a new technique to produce twin calves but the future research on this aspect need to consider the negative effects of twin births in cattle.

REVIEW ON THE IMPACT AND CONSEQUENCES OF THE OCCURRENCE OF MULTIPLE BIRTHS IN CATTLE AND GOATS

Background: The large animal species such as cattle, buffaloes and horses are monotocous with one or sometimes two newborns per birth whereas small farm animal species such as sheep, goats and pigs are usually polytocous animals are highly prolific and especially pigs often produce a dozen newborns at each farrowing. Cattle usually produce only one calf per gestation resulting from ovulation of a single follicle. The most common form of twinning in cattle occurs due to multiple ovulations which may produce dizygotic twins. The twin births in dairy cattle often negatively impacts the reproduction, production, health and reduces the productive lifespan of cows. Therefore, there is a great interest to know the multiple ovulations and multiple births to reduce the twinning rate in dairy cattle herds. Objective: This review updates the status of multiple births and its impact and consequences on production of dairy cattle and goats. Materials and Methods: The related literatures on the multiple births in cattle and goats have been reviewed for which the search was carried out in Google Scholar, PubMed, CrossRef, Banglajol and also the online daily newspapers. Results: Although multiple births with up to quadruplets have been reported from different countries, the prevalence of twin births are commonly reported in dairy cattle. The prevalence of twinning rates are varied widely in different breeds like twin calving in Holstein Friesian cattle is 3 to 5%, 5.6% Spanish dairy herd and 3.9% in Iranian Holsteins, whereas triplet and quadruplet births represent 0.015% and 0.004% of the total births, respectively. Twin calving shorten gestation length, increased dystocia, stillbirths, decrease birth weight, perinatal calf mortality, retained placenta, decrease milk production, increases the occurrence of metabolic diseases, reduced conception rate, increased calving interval, shorten the productive lifespan of the dam and increases overall culling rate. Two strategies- the transfer of a single embryo produced in vitro and follicular drainage of co-dominant follicles at AI have been suggested to prevent twin pregnancies. Conclusion: Multiple births in dairy cattle is not desirable due to negative effects on both cows that calve twins and calves born as twins that result in economic losses in dairy herds. Regardless of the direct effect of multiple births on health and fertility, reducing the occurrence of multiple ovulations to decrease the risk of twin births is desirable to mitigate the negative consequences of twinning in dairy cattle. The estimated losses due to twinning range between US$ 59 to 161 per twin pregnancy and attempting manual embryo reduction decreased the economic losses of a twin pregnancy by US $ 23 to 45. Bangladesh scientists discovered a new technique to produce twin calves but the future research on this aspect need to consider the negative effects of twin births in cattle.

Inducing Ovulation with hCG Improves Fertility Outcomes of Co-Dominant Follicle Drainage to Avoid Twin Pregnancy in Dairy Cows.

Simple SummaryIn dairy herds, twin pregnancies considerably compromise cow welfare, reducing their lifespan and leading to the increased use of antibiotics postpartum. In cows with follicles of pre-ovulatory size at insemination, twins can be avoided by puncturing and draining one follicle. In this report, we propose the use of a recently described manual method of follicular drainage without the need for ultrasound guidance and its association with treatment of the animal with human chorionic gonadotrophin (hCG), thus also increasing fertility compared to the use of Gonadotrophin releasing hormone (GnRH). The manual follicular drainage technique is simple, takes less than 1 min, and can be performed by a clinical veterinarian. In this study, even during heat stress periods follicle drainage plus hCG treatment gave rise to nearly 50% of pregnancies relative to conception rates, compared to 29% observed in non-drained, non-treated control animals or 20% in animals drained and treated with GnRH. This approach is recommended for weekly reproductive program visits.Twin pregnancies are undesirable in dairy cattle as they dramatically compromise cow lifespan and, consequently, herd economy. Clinical problems in cows arise from the time of pregnancy diagnosis to pregnancy loss, abortion, or parturition. The drainage of co-dominant follicles in cows with two or more follicles at insemination prevents twin pregnancy. The objective of this study was to compare the effectiveness of draining the smaller of two follicles through a simplified maneuver not requiring ultrasonography in cows in their third or more lactation, and then inducing ovulation immediately before artificial insemination (AI) with GnRH or human chorionic gonadotrophin (hCG). Animals were monitored by ultrasound at AI and randomly assigned to the groups: follicular drainage and treatment with GnRH (Deph; n = 60), follicular drainage and treatment with hCG (hCG; n = 60), and non-drainage (ND; n = 60) as control cows. On the basis of odds ratios, cows treated with hCG were 2.1 times more likely to become pregnant than control animals. Our results reveal the efficacy of hCG treatment at AI in cows with two follicles of pre-ovulatory size subjected to a simple follicular drainage procedure.

Benefits and Risks of Preventing Twin Pregnancies.

Simple SummaryWhile cows usually give birth to singletons, the incidence of twin births has increased considerably during the past few decades alongside milk production. In most cases, multiple pregnancies arise from the simultaneous formation of two or more ovulatory follicles in either the same ovary or both ovaries. Twin pregnancies have devastating effects on cow welfare and the economy of dairy herds. To prevent them, strategies proposed have been the transfer of a single female beef cow embryo produced in vitro to a cow that is not suitable for producing replacements, or the drainage of co-dominant follicles at insemination to prevent twin pregnancies in cows with genetic merit. Developing strategies to reduce the incidence of multiple ovulations and twin pregnancies should be a main focus of clinicians responsible for reproduction in dairy herds. The two procedures mentioned could be components of a weekly reproductive control program and applied to synchronized cows. As a result, embryo survival should improve, avoiding economic losses associated with twin pregnancies, and beef output from the herd will accordingly increase. Last but not least, if twin pregnancies are prevented, the cow’s general health and welfare state will certainly improve.Clinical problems associated with twin pregnancies have been well established, and twin births are now considered undesirable or even disastrous for the dairy cattle industry and the individual cow. The high incidence of early fetal loss, abortion during the mid-lactation period, dystocia, stillbirth, and placenta retention should be considered a preventable consequence of management, as these disorders greatly compromise the welfare and productive lifespan of a cow carrying or delivering twins. The use of sexed semen generates herd replacements and additional heifers, so a proposed strategy for twin pregnancy prevention is the transfer of a single in vitro-produced female beef cow embryo to cows not suitable for producing replacements. Another proposed strategy is drainage at insemination of co-dominant follicles to prevent twin pregnancies in cows with genetic merit. As a result, embryo survival should improve, economic losses associated with twin pregnancies will be prevented, beef output from the herd will be increased, and the health and welfare of the cow will certainly benefit. In this review, the clinical prospects of preventing or avoiding twin pregnancies using both procedures are discussed.

Size and number of corpora lutea and serum progesterone concentrations when administering two doses of eCG in an estrous synchronization treatment regimen for dairy cattle

There was investigation of whether there were ovulations from co-dominant follicles following eCG administration. In all experiments, there was GnRH injection and CIDR insertion on day 0 (D0), CIDR withdrawal on D8, and cloprostenol administration on D8 (Exp. I and II) or D7 and D8 (Exp. III). Females in the control group were not administered any further treatment. Females in other group(s) were treated with eCG (500 IU) on Day 2 in Exp. I, Day 2 (eCG-2) or 8 (eCG-8) in Exp. II and Day 2 (eCG-2) or Days 2 and 6 (eCG-2-6) in Exp. III. Ovaries were examined using ultrasonography. In Experiments I and II, females had follicle emergence on Day 2. At the time of CIDR removal, more eCG-treated heifers (8/9; Exp. I) and cows (5/6; eCG-2; Exp. II) had co-dominant follicles compared to those in the control group (P < 0.05). Occurrence of ovulations from co-dominant for individual cows was minimal. In Experiment III, the time period from CIDR removal to estrus in cows treated with eCG-2 (68 ± 13 h) was longer compared to cows in the control (37±2 h) and eCG-2-6-treated group (38 ± 5 h; P < 0.05). There was a greater proportion of heifers having ovulations and thus greater progesterone concentration in the eCG-2-6 than eCG-2 group (P < 0.05). Administering eCG twice 4 days apart with the initial administration being two days after GnRH administration, at the time of follicle wave emergence, could induce growth of and ovulation from co-dominant follicles and enhance progesterone production in cattle.

Spatial relationships of ovarian follicles and luteal structures in dairy cows subjected to ovulation synchronization: Progesterone and risks for luteolysis, ovulation, and pregnancy

Objectives were to determine relative ovary location of follicles, GnRH-induced corpora lutea (CL), and older CL present in ovaries as part of ovulation synchronization and their associations with progesterone concentration and risk for luteolysis, ovulation, and pregnancy. Cows were exposed to a timed artificial insemination (AI) program [GnRH-1-7 d-PGF2α (1 dose or 2 doses 24 h apart)-56 h after first or only dose of PGF2α-GnRH-2-16 h-timed AI at 72 ± 3 d in milk]. Blood was collected to assess progesterone when ovarian structures were mapped in 694 cows before GnRH-1 and before and 48 h after PGF2α and, in a subset of cows, size of CL (n = 599) and progesterone (n = 380) at 6 d after AI. Dominant follicles and CL in single-ovulating cows were detected more often in right than left ovaries (follicles before GnRH-1: 60.6% right and GnRH-2: 61.2% right; and CL before GnRH-1: 58.6% right and GnRH-2: 66.4% right). Dominant follicles in single-ovulating cows before GnRH-1 tended to be ipsilateral to the CL more often than contralateral (54.8 vs. 45.2%) with co-dominant follicles identified in both ovaries (19.3%). In response to GnRH-1 or GnRH-2, more left-ovary follicles ovulated contralateral to CL (left to right, 54.7%; right to left, 34.7%) than right-ovary follicles, but fewer left-ovary follicles ovulated ipsilateral to CL (left to left: 45.3%) than right-ovary follicles ovulated ipsilateral (right to right: 65.3%). Preovulatory follicles in single-ovulating cows before PGF2α tended to be detected more often ipsilateral than contralateral to CL induced by GnRH-1 (younger CL; 56.5 vs. 43.6%), but were of equal frequency ipsilateral or contralateral to older CL present before GnRH-1. Luteolytic risk was less in cows bearing co-dominant follicles in both ovaries compared with those in either right or left ovaries. Luteolytic risk in single-ovulating cows did not differ between ovaries. Luteolytic risk was greater for cows bearing older CL (86.5%) than for cows bearing younger GnRH-1-induced CL (65.3%) or both (79.6%). Pregnancy risk at 60 d after AI was or tended to be greater in cows having both CL types compared with either younger or older CL, respectively, partly because of greater embryonic loss in the latter 2 cases. More female calves tended to be carried in right horns when conception occurred after first service, whereas the opposite greater female frequency occurred in left horns after repeat services. Right-ovary dominance is evident before and after GnRH treatment.

Genetic merit for fertility traits in Holstein cows: VI. Oocyte developmental competence and embryo development

The hypothesis of this study was that cows with good genetic merit for fertility traits (Fert+) would produce oocytes and embryos of greater quality than cows with poor genetic merit for fertility traits (Fert-) and that mRNA expression of candidate genes would reflect the observed differences in quality. The aim of the study, therefore, was to determine the effect of genetic merit for fertility traits on morphological classification and mRNA abundance of key genes in immature oocytes and cumulus cells following ovum pick-up and in embryos following superovulation, artificial insemination (AI), and uterine flushing. In experiment 1, 17 Fert+ and 11 Fert- cows, ranging from 54 to 84 d in milk, were submitted to ovum pick-up on 4 occasions during a 2-wk period. Recovered cumulus-oocyte complexes (COC) were morphologically graded. Oocytes and cumulus cells were separated, and mRNA abundance of genes associated with oocyte developmental competence was measured. There was no effect of genotype on the distribution of COC grades or on the mRNA abundance of the candidate genes in grade 1 COC. In experiment 2, 20 Fert+ and 19 Fert- cows, ranging from 71 to 189 d in milk, were submitted to superovulation and AI. The uteri of cows that responded to the superovulation protocol (17 Fert+ and 16 Fert- cows) were nonsurgically flushed 7 d postovulation. Recovered embryos were morphologically graded, and mRNA abundance of genes associated with embryo development was measured in grade 1 blastocysts. The response to the superovulation protocol was assessed by counting the number of codominant follicles on the day of AI, which was similar for both genotypes (22.0 ± 9.7 and 19.8 ± 8.2 for Fert+ and Fert- cows, respectively). There was no effect of genotype on the proportion of transferable embryos recovered or on the mRNA abundance of the candidate genes tested in the grade 1 blastocysts. Of the total embryos classified as blastocysts, however, the Fert+ cows tended to have a greater proportion of grade 1 blastocysts compared with Fert- cows (90% vs. 64%, respectively). In conclusion, genetic merit for fertility traits had a no effect on mRNA abundance of the candidate genes that were examined in immature oocytes and cumulus cells and in embryos recovered after superovulation. The observed differences in morphological blastocyst quality following superovulation would suggest that the superior reproductive performance of Fert+ cows could arise during the later stages of embryo development from d 7 until maternal recognition of pregnancy.

The presence of two ovulatory follicles at timed artificial insemination influences the ovulatory response to GnRH in high-producing dairy cows

This study sought to examine the impact of the presence of two co-dominant (ovulatory) follicles at the time of artificial insemination (AI) on the ovulatory response to GnRH given in a fixed-time AI protocol. The study population comprised 622 lactating dairy cows: 306 (49.2%) with a single follicle, 198 (31.8%) with two bilateral follicles (one follicle per ovary) and 118 (19%) with two unilateral follicles (same ovary). Based on odds ratios, cows with two bilateral or unilateral follicles were less likely (by factors of 0.09 and 0.11, respectively) to undergo ovulation failure compared with cows with one follicle (P = 0.01 and P = 0.02, respectively); the likelihood of ovulation failure decreased 0.75 times with every one-mm increase in follicle diameter for cows with a single follicle, whereas individual follicle diameter was not related to ovulation failure in cows with two bilateral follicles (P = 0.001). The likelihood of double ovulation decreased 0.7 times with every one-mm diameter difference between the larger and smaller follicle for all cows with two follicles (P = 0.001), whereas cows with two unilateral follicles showed a higher (P < 0.05) double ovulation rate than cows with two bilateral follicles. In 116 (58.6%) of the cows with two bilateral follicles, only the larger follicle ovulated in 59.5% cows, whereas only the smaller one ovulated in the remaining 40.5% cows. In these cows, a one-mm size difference between the larger and the smaller follicle gave rise to a 1.12-fold increase in the ovulation failure rate for the larger follicles (P = 0.0001). Cows with two bilateral follicles were more likely (by a factor of 1.5) to conceive than cows with one follicle (P = 0.001). Significant right-left differences were not found in cows with two bilateral follicles, whereas the right ovary was more active than the left in the remaining cows. Our results indicate that cows with two co-dominant follicles at AI show different ovulation patterns to those with one dominant follicle. A higher rate of ovulation failure was observed among cows with one follicle than cows with two follicles, whereas the conception rate was higher for cows with two bilateral follicles than for the remaining cows. In cows with two follicles, double ovulations along with ovulation of the smaller follicle were related to the least size difference between the larger and smaller follicle.

Effect of time of eCG administration on the fate of ovarian follicle in Holstein heifers.

The objective of this study was to investigate the effect of equine chorionic gonadotropin (eCG) on ovarian follicles at three stages of development (emergence, dominance and early static phases) during the first follicular wave (FFW) in Holstein heifers. Heifers (n=20) were randomly assigned into four experimental groups (n=5 in each group). Heifers received eCG (500 IU; Folligon®; Intervet, Holland; i.m) a) on the day of follicle emergence (day of ovulation; group 1), b) on the dominant phase (dominant follicle (DF): the first day in which follicle was observed at ≥10 mm; group 2, and c) on the early static phase (group 3) of the FFW. Control group heifers did not receive any treatment. Daily ultrasonography was conducted to monitor ovarian structure throughout estrous cycle. All treatment group heifers, regardless of the stage of follicle development, displayed follicle growth after eCG injection. Administration of eCG, in group 1, hastened DF detection and induced co-dominant follicles; whereas, in groups 2 and 3, it delayed DF regression, and increased cycle length compared to control. In all treatment group heifers, DF was present 84 h after eCG injection. Maximum diameter of corpus luteum was larger in eCG treated groups compared to control (P<0.05). In conclusion, depending on the time of eCG administration throughout the FFW (emergence, dominant and early static phases), co-dominancy, maintenance of DF, enhancement of follicle and corpus luteum growth and increase in estrous cycle length could be observed in Holstein heifers.

Impact of large ovarian endometriomas on the response to superovulation for in vitro fertilization: A retrospective study

ObjectiveTo assess the response to superovulation for in vitro fertilization (IVF) in patients with unilateral endometriomas with diameter ≥5cm and in the contralateral healthy ovary. Study designThis retrospective analysis of a prospectively collected database included patients who underwent superovulation for IVF/ICSI cycles and had unoperated single unilateral endometrioma with diameter ≥5cm and healthy contralateral ovary. The primary outcome of the study was to compare the number of oocyte retrieved in the ovary with the endometrioma and the contralateral healthy ovary. ResultsThe total number of follicles was lower in ovaries with endometriomas (2.6±1.3) than in healthy ovaries (4.8±2.0; p<0.001). The number of codominant follicles and the total number of oocytes retrieved were lower in ovaries with endometriomas (1.5±0.9 and 2.0±1.2) than in the contralateral ovaries (3.7±1.5 and 4.2±1.7; p<0.001, respectively). The number of oocytes retrieved suitable for fertilization was lower in ovaries with endometriomas (1.5±1.1) than in the healthy ovaries (3.3±1.5; p<0.001). The total number of oocytes retrieved and the number of oocytes retrieved suitable for fertilization were lower in ovaries with endometriomas respectively in 21 (80.8%) and in 20 (76.9%) cases. The decreased responsiveness to ovarian superovulation was confirmed considering women with ultrasonographic diagnosis of deep infiltrating endometriosis. 30.8% of patients had positive HCG; the pregnancy rate was 23.1%. ConclusionThe presence of large endometriomas (≥5cm) at time of IVF significantly decreases the number of oocyte retrieved compared with the contralateral healthy ovaries.

Effect of hormonal synchronisation and/or short-term supplementation with maize on follicular dynamics and hormone profiles in goats during the non-breeding season

This study aimed to evaluate the reproductive response of anoestrous goats that were either hormonally treated and/or supplemented with maize for 9days to determine which treatment combination was the most effective in enhancing follicular development and ovulation rate, and whether these responses were associated with increases in metabolic hormones. The experiment was carried out using 28 does, using a 2×2 factorial design with seven does in each group to test the effect of synchronisation of oestrus, supplementation with maize and their interactions. Synchronisation of oestrous cycles (P<0.001) but not supplementation with maize or the interaction between the two (P>0.05) increased the number of codominant follicles, the diameter of the largest follicle on Day 9 and growth rate of follicles during the period of supplementation. Compared with non-supplemented animals, supplementation with maize increased the total number of follicles observed between Days 7 and 9 (P=0.039). In addition, nutritional supplementation with maize in combination with synchronisation of oestrus increased the ovulation rate by 43% (P=0.074). Interactions between time and supplementation with maize showed that plasma concentrations of insulin, leptin and IGF-1 were greater in does supplemented with maize compared with non-supplemented does (P<0.001). The findings show that hormonal synchronisation had the most influence on modifying follicular development and ovulation in anoestrous goats. Supplementation with maize increased the concentrations of insulin, leptin and IGF-1, which could potentially modify the sensitivity of follicles to gonadotrophins and reduce rates of atresia.

Regulation of Anti‐Müllerian Hormone and Its Receptor Expression around Follicle Deviation in Cattle

The anti-Müllerian hormone (AMH) is an important marker of ovarian reserve and for predicting the response to superovulatory treatments in several species. The objective of this study was to investigate whether AMH and its receptor (AMHR2) are regulated in bovine granulosa cells during follicular development. In the first experiment, granulosa cells were retrieved from the two largest follicles on days 2 (before), 3 (at the expected time) or 4 (after deviation) of follicular wave. In the second experiment, four doses of FSH (30, 30, 20 and 20 mg) or saline were administered twice a day starting on Day 2 of the first follicular wave of the cycle. Granulosa cells and follicular fluid were collected from the two largest follicles 12 h after the last injection of FSH or saline. AMH mRNA abundance was similar in granulosa cells of the two largest follicles (F1 and F2) before deviation (Day 2), but greater in dominant (DF) than subordinate follicles (SF) at the expected time (Day 3) and after (Day 4) deviation (p < 0.05). In experiment 1, AMH mRNA levels declined in both DF and SF near the expected time and after deviation when compared to before deviation. There was no difference in AMHR2 mRNA levels before and during follicular deviation (p > 0.05), but they tended to be greater in DFs than SFs (p < 0.1) after deviation. Experiment 2 showed that AMH and AMHR2 mRNA in granulosa cells and AMH protein abundance in follicular fluid were similar (p > 0.05) between both co-dominant follicles collected from the FSH-treated cows. These findings indicate the followings: AMH mRNA levels decrease in both DFs and SFs during follicular deviation; granulosa cells from heathy follicles express more AMH mRNA compared to subordinate follicles undergoing atresia and FSH stimulates AMH and AMHR2 mRNA expression in granulosa cells of co-dominant follicles.

Lack of FSH support enhances LIF-STAT3 signaling in granulosa cells of atretic follicles in cattle.

Subordinate follicles (SFs) of bovine follicular waves undergo atresia due to declining FSH concentrations; however, the signalling mechanisms have not been fully deciphered. We used an FSH-induced co-dominance model to determine the effect of FSH on signalling pathways in granulosa cells of the second-largest follicles (SF in control cows and co-dominant follicle (co-DF2) in FSH-treated cows). The SF was smaller than DF in control cows while diameters of co-DF1 and co-DF2 in FSH-treated cows were similar. The presence of cleaved CASP3 protein confirmed that granulosa cells of SFs, but not of DFs and co-DFs, were apoptotic. To determine the effect of FSH on molecular characteristics of the second-largest follicles, we generated relative variables for the second largest follicle in each cow. For this, variables of SF or co-DF2 were divided by the variables of the largest follicle DF or co-DF1 in each cow. There was higher transcript abundance of MAPK1/3 and AKT1/2/3 but lower abundance of phosphorylated MAPK3/1 in SF than co-DF2 granulosa cells. Abundance of mRNA and phosphorylated protein of STAT3 was higher in granulosa cells of control SF than FSH-treated co-DF2. SF granulosa cells had higher levels of LIFR and IL6ST transcripts, the two receptors involved in STAT3 activation. Further, lower transcript abundance of interleukin 6 receptor (IL6R), another receptor involved in STAT3 activation, indicated that STAT3 activation in SF granulosa cells could be mainly due to leukemia inhibitory factor (LIF) signalling. These results indicate that atresia due to lack of FSH is associated with activated LIF-STAT3 signalling in SF granulosa cells, as FSH treatment reversed such activation.

Comparison of follicular dynamics and hormone profiles in Boer goats examined during the breeding and non-breeding seasons in the tropics of Queensland, Australia

This study aimed to describe ovarian follicular dynamics in Boer goats (n=14) during the breeding and non-breeding seasons in the tropics of Queensland. Progesterone profiles and follicular dynamics were compared over a 21-day period in the non-breeding season and one oestrous cycle in the breeding season. Between September and October, 100% of goats were in anoestrus while between April and May they were all undergoing ovulatory cycles. The number of follicular waves during a 3-week period of monitoring was greater during the non-breeding compared to the breeding season (4.8±0.1 vs 4.1±0.1, respectively; P<0.05), while the number of codominant follicles (5.6±0.3 vs 6.8±0.3, respectively; P<0.05), growth rate (0.61±0.05mm/day vs 0.81±0.05mm/day, respectively; P<0.05) and the diameter of the largest follicle measured within follicular waves (6.7±0.1mm vs 7.8±01mm, respectively; P<0.05) were less in the non-breeding compared to the breeding season. During the breeding season the interovulatory interval was 19.7±0.2 days. Total number of small follicles (2–3mm) and the total number of follicles ≥3mm from Days 2 to 14 of the period of examination were greater (P<0.05) during the non-breeding compared to the breeding season. In the breeding season, 35.7% of cycling goats showed large anovulatory follicles, which persisted and became luteinized. Ovulatory follicles were derived from the fourth follicular wave in 71% of goats. These results have described differences in characteristics of follicular development in the same Boer goats examined during the breeding and non-breeding seasons. In the non-breeding season, the ovaries remained active and follicles continued to grow to reach the equivalent size of preovulatory follicles. Follicular dynamics in the breeding season was characterized by the development of larger follicles and greater follicular growth rates. Short oestrous cycles and follicular cysts may reduce ovulation rate in Boer goats in the breeding season.

Ovarian endometriomas and oocyte quality: insights from in vitro fertilization cycles

To evaluate whether the presence of endometriomas affects ovarian function. Prospective cohort study. Infertility unit of an academic setting. Twenty-nine women undergoing an IVF cycle. Prospective evaluation of women with unoperated unilateral endometriomas undergoing IVF. The affected and contralateral intact gonads were compared in terms of responsiveness and oocyte quality. Oocyte developmental competence. Ovarian responsiveness and oocyte quality did not significantly differ between the affected and intact gonads. The number of codominant follicles, the number of oocytes retrieved, and the number of suitable oocytes in affected and intact gonads were 3.7 ± 2.4 and 4.1 ± 1.7, 4.2 ± 3.1 and 4.7 ± 2.5, and 3.1 ± 2.6 and 3.5 ± 2.3, respectively. The number of viable embryos and the number of high-quality embryos were 1.8 ± 2.1 and 1.8 ± 1.4 and 1.0 ± 1.7 and 0.8 ± 0.7, respectively. The fertilization rate in the affected and intact gonads was 64% and 64%, respectively. The cleavage rate was 58% and 51%, respectively. The rate of high-quality embryos was 31% and 21%, respectively. In women undergoing IVF, the presence of ovarian endometriomas does not affect oocyte developmental competence.

Ultrasonographic Characterization of Follicle Deviation in Follicular Waves with Single Dominant and Codominant Follicles in Dromedary Camels (Camelus dromedarius)

Follicular wave emergence was synchronized by treating camels with GnRH when a dominant follicle (DF) was present in the ovaries. Animals were scanned twice a day from day 0 (day of GnRH treatment) to day 10, to characterize emergence and deviation of follicles during the development of the follicular wave. Follicle deviation in individual animals was determined by graphical method. Single DFs were found in 16, double DFs in 9 and triple DFs in two camels. The incidence of codominant (double and triple DFs) follicles was 41%. The interval from GnRH treatment to wave emergence, wave emergence to deviation, diameter and growth rate of F1 follicle before or after deviation did not differ between the animals with single and double DFs. The size difference between future DF(s) and the largest subordinate follicle (SF) was apparent from the day of wave emergence in single and double DFs. Overall, interval from GnRH treatment to wave emergence and wave emergence to the beginning of follicle deviation was 70.6 ± 1.4 and 58.6 ± 2.7 h, respectively. Mean size of the DF and largest SF at the beginning of deviation was 7.4 ± 0.2 and 6.3 ± 0.1 mm, respectively. In conclusion, the characteristics of follicle deviation are similar between the animals that developed single or double DFs.

Follicular characteristics and luteal development after follicle-stimulating hormone induced multiple ovulations in heifers1

A protocol based on small doses of FSH was examined for the induction of double or triple (multiple) ovulations in cattle. Ovulation rate, follicular characteristics, and luteal responses were determined. In Exp. 1, three groups of estrous-synchronized, cyclic Holstein heifers were treated once daily, on d 3 to 6 of the cycle, with a FSH product (Folltropin-V): large FSH dose (total of 150 mg; n=18), medium FSH dose (total of 130 mg, n=12), and small FSH dose (total of 80 mg; n=7). Controls received saline (n=6). Prostaglandin F(2α) was injected on d 6, ultrasound-guided aspiration of surplus follicles (if needed) was performed on d 7, and GnRH was injected on d 8 to induce ovulation. The large FSH dose induced growth of more (2.6±0.3, P<0.05) large follicles than controls on d 8; medium and small FSH doses insufficiently stimulated growth of <2 large follicles. Ovulation rates were determined in subgroups of heifers (n=10, 13, 4, and 6, respectively). The large FSH dose induced greater rates (P<0.01) of mostly double and triple ovulations (90% multiple ovulations, 70% double ovulations), most of which (89%) were bilateral, with only 2 out of 10 heifers requiring aspiration of surplus follicles. Medium and small FSH doses induced fewer multiple ovulations (38% and 25%, respectively). Estradiol concentrations on d 8 did not differ among treatments, but the concentration per large follicle in controls was greater (P<0.05) than in FSH treatments. Mean corpus luteum (CL) volume in single-ovulation controls was greater (P<0.05) than that of multiple ovulations in the large FSH group and total CL volume and progesterone concentrations were numerically greater in multiple ovulations. In Exp. 2, the characteristics of follicles aspirated on d 7 from large FSH (n=11) and control heifers (n=10) were compared. Based on estradiol-to-progesterone ratio, 57% of the large FSH-treated follicles were classified as codominant/healthy follicles and 43% as subordinate/early atretic. Although concentrations of estradiol and androstenedione in FSH-treated codominant follicles were less (P<0.05) than in controls, estradiol-to-progesterone ratio indicated that those follicles were steroidogenically active. Finely tuned small doses of FSH administered during the first follicular wave can induce a large incidence of double/triple, mainly bilateral, ovulations in cattle, which may serve as a basis for treatment aimed at promoting twinning in beef cattle.

Unoperated ovarian endometriomas and responsiveness to hyperstimulation

There is a growing consensus that ovarian reserve is reduced after surgical excision of ovarian endometriomas. However, it remains to be fully clarified whether this damage precedes or follows surgery. In order to further elucidate this aspect, we evaluated ovarian responsiveness to hyperstimulation in women selected for IVF with unilateral unoperated endometriomas. The main aim of this study was to compare the number of developing follicles in the affected ovary with that in the contralateral intact gonad as a control. Patients selected for IVF who were diagnosed with one or more monolateral endometriomas (diameter <4 cm) and who did not undergo previous ovarian surgery were retrospectively identified. We compared the number of follicles (diameter ≥ 11 mm) and the number of co-dominant follicles (diameter >15 mm) on the day of hCG administration in the affected and intact ovaries. Among the 84 women selected, the median interquartile range (IQR) number of follicles ≥ 11 mm in the affected and intact ovaries was 5 (3-7) and 5 (3-8), respectively (P= 0.36). The median (IQR) number of co-dominant follicles in the affected and intact ovaries was 3 (2-4) and 3 (2-5), respectively (P= 0.48). The number of co-dominant follicles was lower in the affected ovary in 36 cases (43%, 95% confidence interval: 32-53%). We also failed to identify any statistically significant difference between the two ovaries when evaluating data according to the number of cysts, their dimension, the dose of gonadotrophins used or the number of oocytes retrieved. In women selected for IVF, the presence of an endometrioma does not markedly affect responsiveness to hyperstimulation.

Recurrent endometrioma and ovarian reserve: biological connection or surgical paradox?

Cumulative evidence supports the view that ovarian endometriomas originate from ovulatory events and that the ovarian reserve is reduced following surgery. On these bases, we have hypothesized that the risk of recurrence may be related to the residual ovarian reserve of the operated ovary. We retrospectively selected 45 women scheduled for in vitro fertilization who previously underwent surgical excision of monolateral endometriomas and compared ovarian responsiveness in those who did (n = 24) and did not (n = 21) have a recurrent endometrioma. In the intact ovaries, the mean ± SD number of codominant follicles in women with and without recurrences was 3.5 ± 1.7 and 3.7 ± 2.2, respectively (P = NS). In the affected ovaries, the mean ± SD number of follicles in gonads with and without recurrences was 2.5 ± 2.3 and 1.1 ± 1.5, respectively (P < .05). Ovarian responsiveness is higher in gonads that developed recurrent endometriomas.