Estrous Cycle Length Research Articles

High Carbohydrate, Fat, and Protein Diets Have a Critical Role in Folliculogenesis and Oocyte Development in Rats.

To date, there is no comparative data on the effects of carbohydrates, fat, and proteins, which are macronutrients, on female reproductive functions. Therefore, in this study, we investigated the effects of diets enriched with carbohydrates, fats, and proteins on folliculogenesis and oocyte development in female rats. 21-day-old rats that were just weaned were divided into 4 groups: control, carbohydrate, fat, and protein. The control group was fed with standard chow and the carbohydrate, fat, and protein groups were fed diets enriched with 75% carbohydrate, 60% fat, and 50% protein for 11 weeks, respectively. It was found that high-fat and high-protein diets caused an increase in the estrous cycle length compared to carbohydrate group (p < 0.05). Graafian follicle number decreased in the protein group compared to the control (p < 0.05). However, the atretic follicle number was higher in the fat group compared to the control group (p < 0.05). In the carbohydrate group, Zp1 was found to be lower than the control and protein groups, Zp2 was found to be lower than the control, and Zp3 was found to be lower than the fat group (p < 0.05). While BMP15 was similar between groups (p > 0.05), GDF9 was lower in all diet groups compared to the control (p < 0.05). Foxo3a was lower in the protein group compared to carbohydrate and control (p < 0.05). GAS2 was found to be higher in the control group than the fat group, and higher in the carbohydrate group than the fat and protein groups (p < 0.05). FSH, LH, Progesterone, and E2 levels were higher in all three diet groups than in the control (p < 0.05). Also, significant differences were observed between the groups regarding adiponectin, resistin, and leptin levels. Taken together, high carbohydrate, fat, and protein intake are associated with impairment of the menstrual cycle, depletion of the developing follicle types, and altered expression of folliculogenesis-specific genes and hormones. Therefore, long-term macronutrient diets may result in shortened reproductive periods and reduced fertilization potential in females in the long run.

Staging of Estrous Cycle in Rats using Vaginal Cytology and Visual Assessment

The determination of different phases of estrous cycle in lab animals is important for reproductive interventions and other experiments related to animal reproduction where rats are used as experimental models. A total 21 Wistar albino (which had completed their pubertal stage ( greater than 4 weeks) weighing approximately 100- 200 g were used in this experiment. Visual assessment was done to observe vaginal opening during different phases of the estrous cycle. This was followed by collection of vaginal discharge samples by flushing it with 0.1 ml of distilled water using micropipette. Vaginal cytology was performed in 21 rats thrice daily, along with visual assessment. The average length of estrous cycle in rats was recorded to be 4-5 days with average duration of proestrus, estrus, metestrus and diestrus of 24, 24-36, 12 and 48 hours, respectively. The average length of estrous cycle in rats was 4-5 days with recorded average duration of proestrus, estrus, metestrus and diestrus of 24, 24-36, 12 and 48 hours, respectively. Vaginal cytology can be considered as a better option compared to visual assessment for assessment of reproductive status in rats.

Knockdown of Gonadotropin-Releasing Hormone II Receptor Impairs Ovulation Rate, Corpus Luteum Development, and Progesterone Production in Gilts.

Reproduction is classically controlled by gonadotropin-releasing hormone (GnRH-I) and its receptor (GnRHR-I) within the brain. In pigs, a second form (GnRH-II) and its specific receptor (GnRHR-II) are also produced, with greater abundance in peripheral vs. central reproductive tissues. The binding of GnRH-II to GnRHR-II has been implicated in the autocrine/paracrine regulation of gonadal steroidogenesis rather than gonadotropin secretion. Blood samples were collected from transgenic gilts, with the ubiquitous knockdown of GnRHR-II (GnRHR-II KD; n = 8) and littermate controls (n = 7) at the onset of estrus (follicular) and 10 days later (luteal); serum concentrations of 16 steroid hormones were quantified by high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Upon euthanasia, ovarian weight (OWT), ovulation rate (OR), and the weight of each excised Corpus luteum (CLWT) were recorded; HPLC-MS/MS was performed on CL homogenates. During the luteal phase, serum progesterone concentration was reduced by 18% in GnRHR-II KD versus control gilts (p = 0.0329). Age and weight at puberty, estrous cycle length, and OWT were similar between lines (p > 0.05). Interestingly, OR was reduced (p = 0.0123), and total CLWT tended to be reduced (p = 0.0958) in GnRHR-II KD compared with control females. Luteal cells in CL sections from GnRHR-II KD gilts were hypotrophic (p < 0.0001). Therefore, GnRH-II and its receptor may help regulate OR, CL development, and progesterone production in gilts.

Reproductive Performance of Estrus Pattern in Bachaur Cows of Bihar

Background: The Bachaur is a medium sized draft purpose breed mostly present in Madhubani, Darbhanga and Sitamarhi districts of Bihar and presently the breed is at the verge of extinction. Since no data is presently available regarding the estrus pattern in these cows therefore, present study was designed to document the oestrus intensity, estrus cycle length, estrus behaviour and duration of estrus in these animals. Methods: The total of nine healthy breeding Bachaur cows aged 3 to 5 years were maintained under identical managemental conditions.The estrous cycles of nine animals was synchronized using Cloprostenol Sodium @ 500 mg I/M (Pragma®, Intas, India) in cycling Bachaur cows. Estrus was detected in the morning and evening for external signs of estrus, estrus behavior, intensity of estrus, estrus duration and estrous cycle length. Result: In the present study, mounting or mounted by other animals was observed in more than 70% and sniffing, tried to lick and Flehmen’s reaction was observed in about 66.67% of treated cows. The other parameters like bellowing, restlessness, milk yield reduction, frequent micturition and Flehmen’s reaction were recorded in 44.44%, 55.56%, 44.44%, 55.56% and 66.67%, of animals, respectively. The most appreciable physical sign of estrus recorded was intense swelling of vulva (in 88.89%) however hyperaemia of vulva, copious estrual mucous discharge, pronounced tonicity of uterus, completely dilated os cervix and presence of large palpable follicle on the ovary was observed in 44.44%, 55.56%, 66.67%, 77.78% and 66.67%, of cows respectively.

Estrous activity in nulliparous heifers with divergent genetic merit for fertility traits

This observational study determined the effect of genetic merit for fertility traits on estrous activity and duration and inter-estrous interval in nulliparous dairy heifers. We also compared estrous activity between estrous events with or without conception and determined the effect of genetic merit for fertility traits on age and body weight at time of first detected estrous activity event. Activity monitoring devices (Heatime, SCR Engineers) were fitted to 7-9-mo aged Holstein-Friesian heifers with positive or negative genetic merit for fertility traits (POS FertBV: average +5%, n = 275; NEG FertBV: average -5%, n = 249) and activity data was collected to the end of the first breeding period (15-17-mo). An estrous event was defined as when the activity change index exceeded 19.2 activity units (AU) for ≥6 consecutive h. In total, 2,434 estrous events were identified (POS FertBV: n = 1454; NEG FertBV: n = 980). Estrous event duration was defined as the period when the threshold was first exceeded and when activity dropped below threshold, without another event starting within 24 h of the end of the previous event. This definition included occurrences where activity crossed the threshold multiple times in a day; these were classified as a single estrous event. A second measure, high activity duration, was defined as the total time activity exceeded the threshold. To characterize estrous activity, baseline activity was determined from the previous 7 d of activity. Peak activity and total activity (area under the curve of activity above baseline) were calculated. A fifth variable, inter-estrous interval, was calculated as a proxy for estrous cycle length. Total activity and peak activity were greater in POS than NEG FertBV heifers (total activity: 548 vs 464 AU, SED = 19.6 AU; peak activity: 72 vs 65 AU, standard error of the difference (SED) = 1.5 AU). The POS FertBV group had a mean estrous event duration and high activity duration of 15.1 h and 15.0 h, compared with 14.1 and 14.1 h for the NEG FertBV group (SED = 0.30 and 0.29 h, respectively). Inter-estrous interval did not differ between POS and NEG FertBV heifers (19.5 vs 20.0 d, SED = 0.49). Estrous events associated with conception were shorter than those not associated with conception (mean ± standard error of the mean, high activity duration: 13.0 ± 0.25 h vs 13.9 ± 0.31 h, estrous event duration: 13.1 ± 0.25 h vs 14 ± 0.32 h) and had less total activity (408 ± 15.2 vs 487 ± 18.2 AU). The POS FertBV heifers were more likely to have their first estrous activity event than NEG FertBV heifers by a given age (HR = 1.26, 95% CI = 1.0 to 1.6) or body weight (HR = 1.35, 95% CI = 1.1 to 1.6). The outcomes of this study provide evidence that positive genetic merit for fertility traits is associated with more overt estrous expression. Therefore, estrous expression traits may have potential to be used as earlier-in-life predictors of genetic merit for fertility.

Key Considerations for Studying the Effects of High-Fat Diet on the Nulligravid Mouse Endometrium.

The obesity epidemic continues to increase, with half of US women predicted to be obese by 2030. Women with obesity are at increased risk for not only cardiovascular and liver disease, but also reproductive disorders. Although mouse models are useful in studying the effects of obesity, there is inconsistency in obesity-induction methods, diet composition, and mouse strains, and studies using female mice are limited. In this study, we sought to compare the effects of a 45% high-fat diet (HFD) versus a 60% HFD on the uterine estrous cycle of nulligravid C57BL/6J mice. For 22 weeks, we placed a total of 20 mice on either a 60% HFD, 45% HFD, or each HFD-matched control diet (CD). Both HFDs produced significant weight gain, with 60% HFD and 45% HFD gaining significant weight after 2 weeks and 15 weeks, respectively. Additionally, both HFDs led to glucose intolerance, fatty liver, and adipocyte hypertrophy. Mice fed 60% HFD displayed hyperphagia in the first 12 weeks of HFD treatment. Moreover, 60% HFD-treated mice had a longer estrous cycle length and an increased percentage of estrus stage samplings compared to CD-treated mice. Estrous cycle stage-controlled 60% HFD-treated mice displayed an increased estrogen-to-progesterone ratio and decreased ovarian corpora lutea compared to CD-treated mice, which may underlie the observed estrous cycle differences. There was no significant difference between diets regarding endometrial morphology or the percent of endometrial CD45+ immune cells. Our results indicate that consideration is needed when selecting a HFD-induced obesity mouse model for research involving female reproductive health.

Phoenixin knockout mice show no impairment in fertility or differences in metabolic response to a high-fat diet, but exhibit behavioral differences in an open field test.

Phoenixin (PNX) is a conserved secreted peptide that was identified 10 years ago with numerous studies published on its pleiotropic functions. PNX is associated with estrous cycle length, protection from a high-fat diet, and reduction of anxiety behavior. However, no study had yet evaluated the impact of deleting PNX in the whole animal. We sought to evaluate a mouse model lacking the PNX parent gene, small integral membrane protein 20 (Smim20), and the resulting effect on reproduction, energy homeostasis, and anxiety. We found that the Smim20 knockout mice had normal fertility and estrous cycle lengths. Consistent with normal fertility, the hypothalamii of the knockout mice showed no changes in the levels of reproduction-related genes, but the male mice had some changes in energy homeostasis-related genes, such as melanocortin receptor 4 (Mc4r). When placed on a high-fat diet, the wildtype and knockout mice responded similarly, but the male heterozygous mice gained slightly less weight. When placed in an open field test box, the female knockout mice traveled less distance in the outer zone, indicating alterations in anxiety or locomotor behavior. In summary, the homozygous knockout of PNX did not alter fertility and modestly alters a few neuroendocrine genes in response to a high-fat diet, especially in the female mice. However, it altered the behavior of mice in an open field test. PNX therefore may not be crucial for reproductive function or weight, however, we cannot rule out possible compensatory mechanisms in the knockout model. Understanding the role of PNX in physiology may ultimately lead to an enhanced understanding of neuroendocrine mechanisms involving this enigmatic peptide.

71 Growth and reproductive responses to gonadotropins in gilts fed on ad libitum (AD) or restricted (RS) bases using an electronic sow feeder (ESF)

Abstract Previous work in our laboratory showed that age at puberty was similar for replacement gilts fed on either RS or AD bases using an ESF. The objective of this investigation was to determine the effects of feeding (RS vs. AD) on growth and sexual development in gilts treated with gonadotropins (P.G. 600; Merck Animal Health, Rahway, NJ). Prepubertal crossbred gilts were moved at 150 d of age to an open pen with an ESF (ACCUTEAM, Osborne Industries, Osborne, KS) located in an environmentally controlled, curtain-sided building. A 10-d training period to the ESF ensued, during which all gilts received feed on AD basis. At 160 d of age, gilts were allocated to treatments in a 2-by-2 factorial design. Treatments were RS plus P.G. 600 (n = 9), RS without P.G. 600 (n = 10), AD plus P.G. 600 (n = 8), or AD without P.G. 600 (n = 8). The P.G. 600 treatment was administered at 170 d of age. Estrus detection commenced at d 171 and continued for 32 d. Puberty onset was not affected by feeding basis (P = 0.85), P.G. 600 (P = 0.56), or feeding basis x P.G. 600 (P = 0.25). Time in estrus and body weight (BW) at puberty were also similar between treatments. Estrous cycle length was shorter (P &amp;lt; 0.01, 20.0 vs. 21.2 d, SE = 0.54) for RS compared with AD gilts. Bodyweights throughout the trial were similar between treatments but were affected by day (P &amp;lt; 0.01), typical of growing gilts. Feed disappearance was affected by feeding basis (P &amp;lt; 0.01, 2.30 vs. 4.54 kg/d, SE = 0.03 for RS and AD, respectively) and day (P &amp;lt; 0.01). For pubertal gilts, gain to feed ratio was improved (P &amp;lt; 0.01, 0.29 vs. 0.21, SE = 0.03) in RS compared with AD gilts, but average daily gain (ADG) was greater in AD gilts (P = 0.05, 0.75 vs 0.88 kg/d, SE = 0.09). Data were normalized for the 20-d period before second estrus. Feed disappearance was affected by feeding basis x day, and decreased in AD, but not RS gilts, as gilts approached estrus (P = 0.04). Feeding visits (P &amp;lt; 0.01) and feeding visit duration (P &amp;lt; 0.01) were affected by feeding basis with AD gilts consuming feed more frequently and spending less time eating per visit. In this study, RS feeding did not delay, and P.G. 600 did not hasten puberty onset. Moreover, RS gilts grew slower but were more feed efficient than AD gilts. We continue to find that employment of an ESF may support current estrus detection methods by monitoring feeding behavior in AD-fed gilts.

Length of estrous cycle in Holstein-Friesian upgraded cows

Length of estrous cycle in Holstein-Friesian upgraded cows

Postweaning Social Isolation Alters Puberty Onset by Suppressing Electrical Activity of Arcuate Kisspeptin Neurons

Introduction: Postweaning social isolation (PWSI) in rodents is an advanced psychosocial stress model in early life. Some psychosocial stress, such as restrain and isolation, disrupts reproductive physiology in young and adult periods. Mechanisms of early-life stress effects on central regulation of reproduction need to be elucidated. We have investigated the effects of PWSI on function of arcuate kisspeptin (ARCKISS1) neurons by using electrophysiological techniques combining with monitoring of puberty onset and estrous cycle in male and female Kiss1-Cre mice. Methods: Female mice were monitored for puberty onset with vaginal opening examination during social isolation. After isolation, the estrous cycle of female mice was monitored with vaginal cytology. Anxiety-like behavior of mice was determined by an elevated plus maze test. Effects of PWSI on electrophysiology of ARCKISS1 neurons were investigated by the patch clamp method after intracranial injection of AAV-GFP virus into arcuate nucleus of Kiss1-Cre mice after the isolation period. Results: We found that both male and female isolated mice showed anxiety-like behavior. PWSI caused delay in vaginal opening and extension in estrous cycle length. Spontaneous-firing rates of ARCKISS1 neurons were significantly lower in the isolated male and female mice. The peak amplitude of inhibitory postsynaptic currents to ARCKISS1 neurons was higher in the isolated mice, while frequency of excitatory postsynaptic currents was higher in group-housed mice. Conclusion: These findings demonstrate that PWSI alters pre- and postpubertal reproductive physiology through metabolic and electrophysiological pathways.

Relationship of length of the estrous cycle to antral follicle number in crossbred beef heifers.

Length of the menstrual cycle was positively associated with antral follicle number in women. If this pattern is consistent in cattle, a value-added benefit to using automated activity monitors to determine estrous status could be the ability to predict antral follicle count (AFC). We, therefore, hypothesized that as inter-estrous interval increased ultrasonographic AFC would be greater in crossbred beef heifers. Over 3 yr, crossbred beef heifers (n = 1,394) were fitted with automated activity monitors for 81 d. From days 42 to 46, heifers were submitted for ultrasonographic examination to determine AFC. From days 60 to 81, heifers were visually observed twice daily for 45min for signs of behavioral estrus. Heifers that had a behavioral estrus that coincided with a sensor-based estrus and had a previous sensor-based estrus between 15 and 26 d earlier were used for the analysis (n = 850). A combination of regression analyses and correlation analyses were applied to understand the association between data collected by sensors and follicle number determined by ultrasonographic examination. Antral follicle count was analyzed using the GLM procedure of SAS with estrous cycle length (15 to 26 d) as a fixed effect. Estrus was more likely to initiate in the early morning hours and peak activity was greater (P < 0.0001) when estrus initiated between 0200 and 0800 hours then when estrus initiated at other times of the day. Antral follicle count did not differ due to length of the estrous cycle (P = 0.87). Thus, length of the estrous cycle obtained from three-axis accelerometers cannot be used to predict follicle number in crossbred beef heifers; however, machine learning approaches that combine multiple features could be used to integrate parameters of activity with other relevant environmental and management data to quantify AFC and improve reproductive management in beef cows.

Estrous Cycle Length in the Algerian Arbia Goat: Exfoliative Vaginal Cytology and Serum Progesterone Levels

Estrous Cycle Length in the Algerian Arbia Goat: Exfoliative Vaginal Cytology and Serum Progesterone Levels

Follicular, luteal dynamics and effect of synchronization methods on reproductive responses in Cholistani cows.

The Cholistani cow is considered one of the milch breeds of Zebu cattle. Despite being heat and tick-resistant, it has not yet gained much popularity among Pakistan dairy farmers due to its long calving interval. This study aimed to understand the basic reproductive physiology of Cholistani cows using sonography and reproductive biotechnologies such as estrus synchronization and timed artificial insemination to improve reproductive efficiency. In experiment 1, six Cholistani cows with mixed parity 3.20 ± 1.30 and weighing 400 kg were selected to monitor ovarian dynamics on alternate days by the same sonographer from the onset of heat through ovulation until the next ovulation. Experiment 2 measured the effect of estrus synchronization methods, controlled internal drug release-gonadotropin-releasing hormone (CIDR-GnRH, n = 31) and Ovsynch (OVS, n = 32) on various reproductive parameters. The mean estrous cycle length was 19.81 ± 0.56 days with two follicular waves. The mean inter-ovulatory interval was 20.80 ± 0.52 days, with a preovulatory follicular size of 13.83 ± 2.37 mm. Estrus response was higher (p > 0.05) in controlled internal drug release (CIDR)-GnRH (93.54%) than in OVS (84.37%) cows. Similarly, ovulation and conception rates were higher in CIDR-GnRH (91.66% vs. 68.42%) than in OVS cows (41.37% vs. 33.33%), respectively. In conclusion, CIDR-GnRH results in a better estrus response, higher ovulation rate, and subsequently greater conception rate than OVS in Bos indicus dairy cows.

Ovarian Follicular Development Study in Jersey Crossbred Cows Reared in India

Ovarian follicular wave pattern studies provide the basis for applying reproductive intervention for improving fertility and improving the success of embryo transfer programmes in cattle. Four apparently healthy non-pregnant, pluriparous crossbred Jersey cows reared in a local farm located at Tirupur were utilized for this study. The evaluation was performed more than one plane, and all the measurable follicles (&gt;3mm) were counted and recorded every other day. Various follicular dynamics related parameters were studied such as day of wave emergence, dominant follicle, static phase of dominant follicle, regressing phase of dominant follicle, day of maximum diameter, maximum size, duration of growth, growth rate, duration of atresia, rate of atresia and duration of detection. The Ultrasonographic evaluation was performed every other day throughout an estrous cycle starting from observed estrus (Day 0) to the subsequent standing estrus. A total of 10 normal estrous cycles were monitored for follicular wave pattern, in which 8 out of 10 (80 per cent) were two wave and 2 out of 10 (20 per cent) were three wave estrous cycles. The mean length of 2-wave estrous cycle was 19.25±0.41 days and 3-wave estrous cycle was 21.50±0.50 days. It was concluded that Jersey crossbred cows frequently had 2 wave estrous cycle with pre-ovulatory follicle size 12.62±0.94mm with the growth rate of 1.13±0.12mm/day and the size of pre-ovulatory follicle in 3-wave estrous cycle was lower (10.75±1.25mm) than 2-wave estrous cycle.

PSXI-13 Growth and Onset of Puberty in Replacement Gilts Fed on Ad Libitum Or Restricted Bases Using an Electronic Sow Feeder

Abstract Replacement gilts are typically fed on an ad libitum basis until approximately 135 kg BW at approximately 200 d of age and are bred between 135 and 160 kg BW during their second estrus. The shift to group-housing of the breeding herd makes it difficult to manage animals individually. Thus, utilization of an electronic sow feeder (ESF) enables caretakers to manage animals individually in group-housing situations, by allotting predetermined amounts of feed. The objective was to determine the effect of feeding level on growth and sexual development in gilts. Crossbred gilts, assumed prepubertal, were moved at 150 d of age to an open pen measuring 44.3 m2 located in a curtain-sided building with partially slatted concrete floors and an ESF (ACCUTEAM, Osborne Industries, Osborne, KS). Gilts were acclimated to the ESF during a 10-d period, during which they received feed on an ad libitum basis. At 160 d of age, gilts were randomly assigned to receive feed on either an ad libitum (AD, n = 18) or restricted (2.73 kg/d; RS, n = 19) basis. Estrus detection was performed for 42 d. Feeding level had no effect on age at puberty (P = 0.23). The pubertal estrus length was similar between treatments (P = 0.23); however, AD gilts exhibited a longer second estrus period (P = 0.05) compared with RS gilts (37.6 vs 30.8 h, SE = 3.6). Estrous cycle length was not affected (P = 0.72) by feeding level. There were no effects of feeding level (P = 0.36) or feeding level x day (P = 0.53) on BW; however, there was an effect of day (P &amp;lt; 0.01), indicative of growing gilts. Feed disappearance was affected by feeding level (P &amp;lt; 0.01, 4.25 vs. 2.68 kg/d, SE = 0.05 for AD and RS, respectively), day (P &amp;lt; 0.01) and feeding level x day (P &amp;lt; 0.01). Total station visits were affected by feeding level x day (P = 0.05). Non-feeding visits were affected by feeding level (P &amp;lt; 0.01, 1.0 vs. 3.7, SE = 0.22) and day (P &amp;lt; 0.01) but not feeding level x day (P = 0.20). Feeding visits were affected by feeding level x day (P &amp;lt; 0.01). Data were then normalized to the 20-d period before second estrus. Feed disappearance was affected by feeding level x day (P &amp;lt; 0.01), with feed disappearance decreasing in AD, but not RS, gilts as they approached estrus. During this 20-d period, BW was affected by feeding level x day (P &amp;lt; 0.01), with AD gilts having improved growth compared with RS gilts. In this study, feeding level did not affect age at puberty; however, utilizing an ESF may augment current estrus detection methods by monitoring feeding behavior.

Effect of transvaginal oocyte aspiration on progesterone concentrations and estrous cycle length in domestic jennies

With the growing interest in developing assisted reproductive techniques for breeding or animal preservation purposes, transvaginal oocyte aspiration or ovum pick up (OPU) has become an established technique for collecting oocytes and in vitro embryo production in the horse. However, no studies have explored the impact of OPU on the estrous cycle and progesterone dynamics in jennies. Our work aimed to investigate the effect of the OPU procedure on estrous cycle length and plasma progesterone concentration in jennies. Ten healthy Argentinian native domestic jennies aged 3 to 12 years were used for this experiment. A total of 18 estrous cycles were evaluated during one breeding season: eleven control and seven cycles with OPU. Jennies were monitored every second day by ultrasonography until ovulation was detected (ovulation day = day 0 of the estrous cycle). Blood samples for progesterone determination were obtained from two control and three OPU cycles every two days for an entire estrous cycle (control) and from OPU day until the following ovulation (OPU group). Progesterone concentration was measured by Chemiluminescent Microparticle Immunoassay. For the OPU procedure, jennies on days 8 and 12 of the estrous cycle with more than six total follicles and no follicles larger than 25 mm were selected. The OPU procedure was performed as described by Bragulat et al. (Theriogenology. 2023; 195:199-208). Student's t-test was used to compare estrouscycle length, and analysis of variance (ANOVA) was conducted to determine whether there were any statistically significant differences in progesterone concentrations between control and OPU groups. The estrous cycle length of jennies subjected to OPU was significantly longer (P=0.02) than the control group (mean ± SEM, minimum / maximum values): Control, 22.64 ± 0.85 16/27 days; OPU, 26,00 ± 0.93 23/28 days. No luteinized structures were found after OPU sessions. In control estrous cycles, progesterone concentration increased after ovulation, reaching a peak on day 12 (mean ± SEM values; 36.20 ± 0.99 ng/ml) and decreasing to baseline concentration from day 16 (4.65 ± 3.18 ng/ml) to day 20 (0.75 ± 0.21 ng/ml). The results showed a significant difference in progesterone concentrations between the control and OPU groups (p = 0.003). Specifically, jennies subjected to OPU had lower progesterone concentrations from day 10 to 14 compared to the control group. Interestingly, both groups reached a similar baseline by day 16 until the following ovulation. Therefore, these preliminary data suggest that follicle aspiration between days 8 and 12 may slightly prolong the estrus cycle in donkeys and could affect progesterone plasma concentrations in jennies. However, further studies are required to confirm these results.

Toxic effect of Syzygium guineense ethanolic extract on female reproduction in rats: An evidence from a 10 week repeated-dose toxicity study

IntroductionIt has been reported that some herbal products affect reproduction. To date, reproductive toxicity of Syzygium guineense has not been investigated although the plant is widely used in treating fertility related problems. Thus, the objective of the current study was to investigate the toxic effects of 70% ethanol extract of S. guineense leaves on the reproductive function and histopathology of reproductive organs in female rats. MethodsEighty female Wistar albino rats were randomly divided into four groups where each group consisted of 20 rats. Rats in the first three groups were treated with S. guineense extract at doses of 250, 500 and 1000 mg/kg body weight, respectively. The fourth group served as a control group. The rats were treated for ten consecutive weeks. The length of estrous cycle, reproductive indices, pregnancy outcomes, and number of postnatal deaths were recorded. At necropsy, organ weight was measured, gross and histopathological examinations of ovaries, uterus, and vagina were conducted. ResultsTreatment of rats, with high dose (1000 mg/kg) of S. guineense, significantly prolonged the duration of estrous cycle and reduced weight of uterus and ovaries as well as the number of total and live birth pups. However, there were no significant changes observed in reproductive indices and gross morphology as well as histopathology of ovaries, uterus, and vagina. ConclusionAdministration of high doses of S. guineense could be toxic to some aspects of the reproductive system of female rats and might also affect reproduction. Therefore, consuming high dose of S. guineense leaves is not recommended.

Effect of cytobrush technique in mares

Several studies have been done correlating transcervical techniques or mechanical manipulation on the endometrium and its effect on the equine estrous cycle length in mares. However, the effect of the endometrial cytobrush technique on the estrous cycle and its use for the study of endometrial-ovarian relationships is still unknown. The aim of this study was to evaluate the usage of the endometrial cytobrush technique for study of the role of endometrial receptors and genes involved in the luteolytic mechanism. The study was divided in three groups: single endometrial cytobrush (CBS), endometrial samples collected in different animals on days 12, 14, and 16 (n = 5 /day); endometrial samples collect multiple times (CBM) in the same animal on days 12, 14, and 16 (n = 5/day); no endometrial samples collection (CSN). Blood samples were collected daily from ovulation to subsequent ovulation on the three groups to evaluate progesterone (P4) concentration. Additionally, on Day 12, blood samples were collected at h0 (just before cytobrush collection), 15 min, 30 min, h1, h2, and h4 to evaluate concentrations of P4 and a metabolite of prostaglandin F2α (PGFM). The gene expression was compared among the preluteolytic, luteolytic, and postluteolytic periods. The day before P4 concentration decreased by 20% from the previous day with an uninterrupteddecrease thereafter was defined as the beginning of luteolysis (luteolytic period), and the first day P4 concentration decreased to < 1.0 ng/mL was defined as the end of luteolysis (postluteolytic period). The interovulatory length, beginning of luteolysis, and concentrations of P4 and PGFM did not differ among the groups (P > 0.05). Three animals in the CBM group developed 5 ± 2 mm of endometrial fluid after the second cytobrush collection. However, these animals did not have endometrial fluid after ovulation. According to endometrial gene expression, in the CBM group, the prostaglandin-endoperoxide synthase 2 (PTGS2) was upregulated during luteolysis (P < 0.05), PGF transporter (SLCO2A1) was upregulated after luteolysis, and 15-hydroxyprostaglandin dehydrogenase (HPGD) was downregulated during luteolysis. In the CBS group, oxytocin receptor (OXTR), prostaglandin F2 receptor (PTGFS), and (HPGD) were upregulated during luteolysis (P < 0.05). SLCO2A1 was upregulated during and after luteolysis (P < 0.05). These results suggest that endometrial cytobrush technique does not influence the length of the cycle and is a viable method for studying endometrial gene expression of genes associated with luteolysis in a single sample collection in mares.

Reproductive characterization of hair ewe in the American tropics: a review part 1

Objective: To carry out a reproductive characterization of the breeds of hair ewe in the tropical region of the Americas. Design/Methodology/Approach: A search of scientific information about the reproductive variables of breeds of hair ewe was carried out and the results were analyzed in the Web of Science, Redalyc, Dialnet, PubMed, SciELO, and Latindex databases. Results: We described and discussed the highly-variable onset of puberty in ewe lambs. Similar results were found in adult ewes regarding the duration and occurrence of the estrous, estrous cycle length, seasonal anestrous, ovulation rate, fertility, gestation, and prolificacy. Study Limitations/Implications: Information about the reproductive variables of breeds of hair ewe is poorly known or non-existent. Findings/Conclusions: The onset of puberty in 15-43 kg ewe lambs ranges from 175 to 335 d of age. The estrous cycle of hair ewe in Mexico lasts 17 d in autumn-winter and 21 d in spring-summer. In Brazil, this cycle lasts 17 d in spring-summer and 18 d in autumn-winter. In the United States of America and Venezuela, the estrous cycle length was similar in both periods of the year. The occurrence of the estrous reached 97.1 % in autumn-winter and 76.5 % in spring-summer. The duration of the estrous ranges from 16 to 52 hours. Seasonal anestrous occurs from May to July. The ovulation rate ranges from 1 to 3 oocytes. The percentage of fertility fluctuates between 80 and 100 % in temperate months and reaches 37 % in warm ones. Gestation lasts from 144 to 152 d. Prolificacy ranges from 1.0 to 2.2 offspring per ewe. The lambing interval ranges from 244 to 294 d.

Estrous synchronization in cattle, sheep and goat

Synchronization of estrous refers to manipulating the estrous cycle or induction of estrous to bring a large number or group of female animals into estrous at a short, determined time. An estrous cycle is a rhythmic event in the female animal from one estrous phase to the next. The normal estrous cycle length is 21 days in cows, 20 days in doe, and 17 days in the ewe. The hormones used in estrous synchronization are estrogen, progesterone, GnRH, and prostaglandin. Estrous synchronization helps shorten the breeding period instead of females being bred over a period of normal length, and this depends on the treatment protocols to be followed. Combining GnRH with prostaglandin F2α (PGF2α) and a progesterone-based synchronization program has shown a novel direction in cattle's estrous synchronization, which causes manipulation in follicular development. Estrous synchronization protocol should be followed based on managemental capabilities and expectations of the farmer. This review article was compiled to summarize the protocols used for estrous synchronization in different species.