Beginning Of Estrus Research Articles

Reproductive Response of Hair Sheep to Short or Long Duration Estrus Synchronization Protocols

Objective: Evaluate the reproductive response of hair ewes treated with estrus synchronization protocols that included a progesterone-releasing intravaginal device (CIDR) for a period of 7 or 12 days. Methodology: During the end of winter, ewes were randomly allotted to one of two estrus synchronization protocols: 1) Short-term protocol (SD), ewes (n=24) received a CIDR on Day 1 and removed on Day 7, and received 400 IU of equine chorionic gonadotropin (eCG) and 0.125 mg of cloprostenol; 2) Long-term protocol (LD), ewes (n=24) received a CIDR on Day 1, retired on Day 12 and received 400 IU eCG. Ewes showing estrous behavior were bred with a mature ram. Results: There were no differences (P>0.05) in the estrus response in both groups of ewes (100 vs 95.8% for SD and LD, respectively), the pregnancy rate (87.5 vs 87.5%), prolificacy (1.95+0.1 vs 2.2+0.1 lambs/ewe), hours between CIDR removing and the beginning of estrus (34.4+8.1 vs 34.8+9.2 h), and estrus duration (39.7+2.9 vs 39.9+4.7 h). At CIDR removal, ewes in the PL group showed a greater diameter (P<0.05) for the largest follicle in both ovaries (5.42+0.3 and 5.42+0.4 mm for the follicle in the left and right ovaries, respectively) vs PC ewes (4.25+0.1 and 4.29+0.1 mm). Limitations of study: Results observed in the follicle diameter could be due to low circulating progesterone levels in the LP group, which must be confirmed in future studies. Conclusions: The short protocol for estrus synchronization can be used in hair ewes under temperate conditions, without affecting their reproductive response.

Synchronization of the reproductive cycle is bright for the regulation of lambing

Purpose: to study the effect of the duration of the use of progesterone for synchronization of the sexual cycle and the elaboration of the Dorper breed in the reproduction season.Materials and methods. The object of the study was bright (n = 43) of the Dorper breed. Yarok was synchronized by the introduction of pessaries with progesterone (sidr) and injection on the day of removal of the CIDR of a chorionic gonadotropin of horses (HCH) in a dosage of 500 ME. Sheep were divided into three groups: I group (n = 13) – for 9 days a CIDR with progesterone (CIDR® OVIS, Zoetis, Madrid, Spain) was introduced for 9 days; Group II (n = 9) – CIDR was introduced for 11 days; Group III (n = 21) – CIDR was introduced for 13 days. In all three groups on the day of removal of the pessary, intramuscular injection of the HCL 500 IU is made. Upon completion of synchronization, observations of the signs of estrus were observed within 72 hours. Jacket was judged by the beginning of the estrus, when the state of immobility and the allowance of the ram of the ram was recorded. The duration of estrus was measured from the moment of the first intercourse until the sheep began to reject the male.Results. The average interval between the removal of the pessary and the beginning of estrus in three groups was: in the first group – 38,7±5,1 hours; in the second group – 34,6±5,8 hours; In the third group – 52,4±4,4 hours. The minimum time from the extraction of CIDR to the beginning of the estrus was installed in the first group – after 12 hours, the maximum time was recorded in the third group – 96 hours.Conclusion. The reliable effect of progesterone containing a gestagen drug on the reproductive indicators of the fierce, mainly at the beginning of the estrus, has been demonstrated. The most optimal is the use of CIDR with a constant rate of progesterone release by 9-11 days, since these groups have a 100% reaction to hormonal treatment.

Transforming growth factor-β1 mediates the SMAD4/BMF pathway to regulate ovarian granulosa cell apoptosis in small tail Han sheep

Transforming growth factor (TGF)-β1 is an important multifunctional cytokine in the TGF-β signaling pathway, which is involved in the molecular regulation of multiple activities, including follicle development and ovulation in female reproductive physiology. However, the biological function of TGF-β1 in follicular development and in regulating the proliferation or apoptosis of granulosa cells in small tail Han sheep remain unclear. In this study, we analyzed the expression levels of TGF-β1 in the ovary at the follicular stage in small tail Han sheep. We further examined the effects of TGF-β1 on the viability, proliferation, and apoptosis of granulosa cells. Differential expression of TGF-β1 at the mRNA and protein levels was detected in the ovaries between the beginning of estrus and at preovulation. Cell Counting Kit-8, 5-ethynyl-2′-deoxyuridine (EdU) labeling, and flow cytometry assays showed that adding 5 and 10 ng/mL TGF-β1 could improve the viability and growth rate, reduce the apoptosis rate, and reduce the expression level of the pro-apoptotic factor Bcl-2-modifying factor (BMF) in granulosa cells. Treatment of 10 ng/mL TGF-β1 at all time points (except 72 h) significantly increased the positive rate of EdU labeling compared to that of the control group. RNA interference of SMAD4 reversed the decreased apoptosis rate caused by stimulation with 10 ng/mL TGF-β1, accompanied by a corresponding increase in the BMF expression level. Collectively, these results indicate that TGF-β1 plays a role in the ovarian follicular-phase activity of small tail Han sheep by inhibiting the apoptosis of sheep granulosa cells through the SMAD4/BMF pathway to promote proliferation and vitality. This study provides new insight into the molecular mechanism underlying TGF-β1 function regulation in granulosa cells, suggests a new target for the regulation of follicle development, and expands the new field of animal reproduction regulation technology.

Effect of Immunocastration on Culled Sows-A Preliminary Study on Reproductive Tract, Carcass Traits, and Meat Quality.

The Bísaro pig is a Portuguese autochthonous breed greatly appreciated for its meat quality and is mainly reared outdoors. Immunocastration could be a solution to avoid undesirable pregnancies and boar taint in cull sows. The present study tested three immunocastration protocols (with Improvac®) according to their reproductive cycle. The first inoculation was performed two weeks after farrowing (IM1, n = 5), at the beginning of estrus (IM2, n = 5), and one week after the end of estrus (IM3, n = 5), followed by a second administration four weeks apart. A control group (C, n = 5) was also included in the same housing conditions. The sample collection included the reproductive tract for morphometric evaluation, neck fat for the quantification of boar taint compounds, and a portion of the Longissimus thoracis et lumborum for meat quality trait assessment. The reproductive tracts from intact sows (C) were significantly heavier compared to the immunocastrated groups (p < 0.05) (1.403 kg C to 0.508 kg IM1, 0.590 kg IM2, and 0.599 kg IM3), suggesting the regression of the reproductive tract to nonstimulated conditions due to immunization against GnRH. The IM1 group exhibited significantly smaller reproductive tract measurements compared to group C for most of the evaluated segments (p < 0.05). No marked differences were observed in the meat quality traits. Therefore, immunocastration can be used in culling sows to avoid ovarian activity, and it is not detrimental to pork quality traits.

Changes in serum progesteron and 17beta-estradiol concentration after application of Suprelorin (4,7 deslorelin acetate) implant for estrus induction in bitches

Since bitches are monoestrous animals, their sexual cycle occurs much less often than other domestic animals, and their reproductive capacity is potentially less. That is why manipulations with the sexual cycle of bitches and their correction are gaining more and more interest. Estrus induction is essential to commercial breeding owners for several reasons. Understanding the processes that occur during each stage of the sexual cycle, it can be safely manipulated. There are many methods for stimulating estrus, but not all of them have found their practical application. The implant Suprelorin (4.7 mg Deslorelin), which is primarily registered for the pharmacological castration of dogs and cats, has also found its use for the induction of estrus in bitches, since at the beginning of its activities, it stimulates the secretion of gonadotropin (GnRH), which triggers the synthesis of follicle-stimulating and luteinizing pituitary hormones. This initial mechanism of action of Deslorelin implants is known as the flash effect and causes heat in almost 100 % of bitches. Despite numerous publications on the use of the implant, its impact is still being investigated. The article presents changes in progesterone and estradiol after using the Suprelorin implant for estrus induction and compares the course of an induced sexual cycle with a spontaneous one. The study was conducted on 13 sexually mature bitches, 7 of them received the Suprelorin implant no earlier than 150 days after the last estrus, and 6 of them were bitches with spontaneous estrus, which were included in the control group. The implant was removed at the beginning of estrus when the progesterone level increased above 3 ng/ml. In 6/7 females, this day fell on the 10th day after the implant was inserted, and in 1/7 – on the 9th. Ovulation occurred two days after the LH peak in all bitches from the experimental group, which corresponded to the 12th day in 6/7 bitches and the 11th day in 1/7 bitches from the introduction of the implant. The estradiol peak in the control group was observed faster than in the experimental group. It occurred on average on the 8th day (mediam 8 (7–9)) from the beginning of estrus, in one bitch on the 7th day, in three - on the 8th, and in two – on the 9th day, respectively. In the experimental group, the estradiol peak occurred on the 9th day after the implant (mediam 9 (8–9), in two bitches on the 8th, and five – on the 9th. But the obtained results indicate that in most bitches of the research group, the estradiol peak occurred one day before the LH peak (5/7) and only in 2/7 two days before the LH peak, which is typical for spontaneous estrus, so despite, that,, the peak of estradiol in the experimental group was observed later than in the control group, and ovulation itself occurred faster. Quantitatively, the level of sex hormones was higher in the experimental group, and the sexual cycle was more predictable.

Effect of Timing of Artificial Insemination on Fertility of Cows and Calf Sex Ratio in Arsi Cows

An on-station study was conducted to investigate the effect of the interval between artificial insemination (AI) and the beginning of estrus on the fertility and sex ratio of offspring in Arsi cows. Standing to be mounted was considered the beginning of estrus, and artificial inseminations were made 6 h (Group 1), 12 h (Group 2), 18 h (Group 3) and 24 h (Group 4) after the onset of estrus in the cows. Overall, 50 cows with parity between 2 and 4, body weight ranging from 250 to 300 kg were used for the purpose of this study. Ovulation was synchronized by administration of PGF2α hormone. Pregnancy diagnosis was performed by rectal palpation at 90 to 120 days post AI. Pregnancy rates were 60%, in each of the Groups 1, 2, 3 and 50% in group 4. The highest female to male ratio (P=0.041) of calves was obtained in Group 1. Whereas the highest male to female ratio was recorded in group 4. The number of artificial inseminations per pregnancy was within the economical limits in all groups. In conclusion, the results of this study indicated that the variation in time interval between the onset of estrus and artificial insemination alters the sex ratio of offspring in Arsi cows without affecting fertility parameters.

Determination of estrus duration based on cervical mucus characteristics in Aceh cattle using camera-equipped artificial insemination endoscope

This study aimed to determine the length of the estrus period in Aceh cows based on changes in the characteristics of cervical mucus observed using a camera-equipped artificial insemination (AI) endoscope. This study used twelve healthy and reproductively sound cows aged 4-6 years. All cows were synchronized using prostaglandin F2α (PGF2α) injected intramuscularly twice, 11 days apart. Estrus detection was conducted 24 hours following the second injection of PGF2α three times daily for 30 minutes, respectively. Estrous cows were then subjected to the examination of their cervical mucus at 0, 6, 12, and 18 hours after the beginning of estrus. This study showed that out of 12 samples, only eight cows exhibited estrus signs. Characteristics of cervical mucus of cows at 0 and 6 hours of estrus were transparent. At 12 hours of estrus, five cows showed transparency, and the remaining three cows showed cloudy cervical mucus. Meanwhile, at 18 hours of estrus, all sampled cows showed cloudy cervical mucus then regarded as the end of the estrus. That means the estrus length of Aceh cows in this study was 15.75 ± 3.11 hours. It can be concluded that the determination of the duration of estrus in Aceh cows based on changes in the characteristics of the cervical mucus can be carried out using an AI endoscope with a camera. For further research, it is suggested to apply this estrus detection technique in the implementation of AI and determine the pregnancy rate.

Increasing the success of artificial insemination through control of local cattle estrus as a genetic resource

This paper aims to find out the application of I.B. in cows and the control of estrus to determine fertility and conception rate in cows. The research was conducted in two stages: field research to determine the influence of I.B. time on conception rate. Local cows in I.B. amounted to 62 heads, and crossbred cows with as many as 100 heads were grouped based on I.B. time and parity and analysed with the Z test. Fertility is determined by the size of the dominant follicle using ultrasonography, and the number of gardenings is determined 30 days after I.B. and 60 days of rectal palpation. Average conception rate at the beginning of estrus (45.70%), middle estrus (60.59%), end of estrus (68.91%), and six hours after estrus (61.55%). I.B. time had a significant effect (P&lt;0.05) on the conception rate. Based on the results of this study, it was revealed that parity-3 had the highest pregnancy rate for local cattle (70.34%), while crossbreed cattle had the highest pregnancy rate at parity-2 (56.79%). The follicle size in Bali cattle was the same as that of local south coast cattle, including the small follicle size category.

Circulating endocrine, metabolic, and haematologic indices during the peripartum period of Darehshori mares

The characteristics associated with equine peripartum period are different from those of other periods. Information concerning the values and dynamic changes of circulating peripartum endocrine, metabolic, and haematologic indices may improve the understanding of the whole body haemostatic patterns which lead to parturition, lactogenesis, and estrus in the horse. The present study aimed to evaluate these changes around parturition in Darehshori breed. For this purpose, blood sampling was performed on six clinically healthy Darehshori mares (10 years old) about one week prior to parturition, three days following parturition, at the beginning of estrus, and one week after estrus. Circula­ting values ​​of glucose, estrogen, progesterone, cortisol, T3, T4, TG, cholesterol, HDL, LDL, VLDL, RBC, HGB, HCT, MCV, MCH, MCHC, WBC, neutrophil, lymphocyte, and PLT were assessed in all samples. Progesterone concentrations were minimum before parturition and increased significantly one week after foaling heat (P=0.035). Cortisol level was significantly higher during foaling heat compared with other periods (P=0.029). T4 levels significantly increased from pre- to post-partum periods (P=0.001), but T3 showed increased and decreased values during the study period. All serum lipid profile parameters were significantly reduced from pre to postpartum period (P&lt;0.05). Haematological parameters in mares significantly changed during the peripartum period (P&lt;0.05). Based on the results, the metabolic, haematological, endocrinological, and stress indices in Darehshori mares were found to change around parturition and the first estrus. These changes were largely dependent on hormonal mechanisms related to pregnancy and parturition occurring in normal mares.

Timed Artificial Insemination by Combining Estrous Behavior Observation With Deslorelin Treatment in Jennies

The purpose of this study was to determine the optimal time for ovulation induction and artificial insemination (AI) based on the relationship between estrous behavior and ovulation in jennies. Thirty-two jennies were teased by one jackass for 1 hour per day during 46 days and estrous behaviors were recorded, while the follicular development and ovulation was examined by ultrasound. Furthermore, another 31 jennies were teased by one jackass as the teasing group (group T), which were injected with Deslorelin at 2 and 4 days after the onset of estrus, and AI was performed at 8 hours after each injection. Moreover, Ultrasound was performed on the follicle development of 23 jennies as the ultrasonography group (group U). Injection with Deslorelin when the follicle diameter ≥ 30 mm, and AI was performed at 8 hours later. The results showed that mouth clapping was the specific estrous behavior of jennies and indicated the beginning of estrus. The mean time for jennies to develop dominant follicles (≥30 mm) after the onset of estrus was 3.5 ± 1.3 days, and the mean time between the onset of estrus and ovulation was 5.1 ± 1.5 days. Estrous behaviors ended 0.5 ± 1.2 days after ovulation. After AI, there were no significant differences in ovulation (96.8% vs. 91.3%) and conception rates (40.0% vs. 38.1%) between group T and U. The optimal breeding time of jennies can be determined by jackass teasing and hastening ovulation by Deslorelin injection.

Maternal diet can alter oocyte mitochondrial number and function

The purpose of this study was to determine the optimal time for ovulation induction and artificial insemination (AI) based on the relationship between estrous behavior and ovulation in jennies. Thirty-two jennies were teased by one jackass for 1 hour per day during 46 days and estrous behaviors were recorded, while the follicular development and ovulation was examined by ultrasound. Furthermore, another 31 jennies were teased by one jackass as the teasing group (group T), which were injected with Deslorelin at 2 and 4 days after the onset of estrus, and AI was performed at 8 hours after each injection. Moreover, Ultrasound was performed on the follicle development of 23 jennies as the ultrasonography group (group U). Injection with Deslorelin when the follicle diameter ≥ 30 mm, and AI was performed at 8 hours later. The results showed that mouth clapping was the specific estrous behavior of jennies and indicated the beginning of estrus. The mean time for jennies to develop dominant follicles (≥30 mm) after the onset of estrus was 3.5 ± 1.3 days, and the mean time between the onset of estrus and ovulation was 5.1 ± 1.5 days. Estrous behaviors ended 0.5 ± 1.2 days after ovulation. After AI, there were no significant differences in ovulation (96.8% vs. 91.3%) and conception rates (40.0% vs. 38.1%) between group T and U. The optimal breeding time of jennies can be determined by jackass teasing and hastening ovulation by Deslorelin injection.

Hormonal Protocols for the Synchronization and Induction of Synchronized Estrus in Dairy Ewes Kept under Tropical Conditions

Background: Lacaune is an important sheep breed and shows reproductive seasonality which affects dairy product supply. The most common hormonal protocols are based on progesterone-releasing devices in order to reach reproductive activity. Due to international consumer demand for natural, green, and clean methods, such issues encourage the minimal or absent use of synthetic hormones in livestock. In this sense, the present study tested the efficiency of induction and estrus synchronization protocols in lacaune ewes, considering: application interval of synthetic prostaglandin at the breeding season; length of synthetic progesterone exposure; and eCG dose at the outbreeding season.Materials, Methods &amp; Results: In study 1, 52 ewes were submitted to estrus synchronization protocol using two doses of d-cloprostenol 7 or 9 days apart. In study 2, 47 ewes were submitted to estrus induction protocol using an intravaginal device containing 60 mg of medroxyprogesterone acetate maintained for 6, 9, or 12 days. In study 3, 46 ewes were submitted to synchronized estrus induction protocol using intravaginal progesterone device for six days. On the fifth day, d-cloprostenol and 300 IU or 400 IU of eCG were administered. For all studies, signs of estrus beginning/ending were recorded and natural mating was performed. After 30 days, transrectal ultrasound was performed for pregnancy diagnosis. In study 1, groups presented similar rate of estrus behavior (78.8%) and pregnancy (average 75.6%). Meanwhile, compared to G9days (37.8 ± 7.2 h), interval between the second dose of prostaglandin and beginning of estrus was smaller in G7days (31.5 ± 7.8 h). No difference was found among variables studied in study 2 (P &gt; 0.05), nevertheless the SD for the estrus duration was shorter (P &lt; 0.05) in G6days and G12 days when compared with the G9days. Equally, the SD for the interval between sponge withdrawal and beginning and end of estrus was shorter (P &lt; 0.05) in G12days when compared with the G9days. The pregnancy rate, at 30 days, was 71.1%. With regards to study 3, there was no effect of parturition order on sexual behavior between experimental groups (P &gt; 0.05). Equally, no differences were found between variables studied (P &gt; 0.05). The pregnancy rate was 52.2% and number of concepts was 1.5 ± 0.6.Discussion: This paper provides important data on estrus synchronization protocols in dairy sheep kept under tropical conditions. In study 1, both d-cloprostenol protocols were efficient in synchronizing estrus of dairy ewes and reached a fair pregnancy rate. Therefore, it was demonstrated that a d-cloprostenol treatment was a viable alternative to a progestogen treatment, commonly used for estrus synchronization in ewes even during the breeding season. In study 2, all protocols (6, 9 and 12 days of exposure to synthetic progesterone) were efficient in inducing and synchronizing estrus in dairy ewes during the outbreeding season. Therefore, considering not only its efficiency but also the reduction of damage to the vaginal microbiota, the authors strongly encourage the use of the 6-day synthetic progesterone exposure protocol. The third study showed that it is possible to reduce the eCG dose (400 to 300 IU) in dairy ewes while maintaining protocol efficiency, saving 25% of the farmer spending, and avoiding high doses that are related to immune resistance and lower progressive fertility response to IA. In conclusion, the present study verified the efficiency of different hormonal protocols applied for dairy Lacaune ewes kept under tropical conditions, demonstrating that it is possible to decrease: (i) the interval between prostaglandin applications for 7 days apart during the breeding season; (ii) the length of exposure to synthetic progesterone for 6 days; and (iii) the eCG dose to 300 IU during the outbreeding season.

Time of copulation during estrus period on estrus duration and LH response in Boer goats

The objectives of this investigation were to determine the effect of the time of copulation during the estrus period on estrus duration and luteinizing hormone (LH) response in goats. A controlled randomized study with two replicates (first = n = 12; second = n = 24), in which Boer does were divided at each replicate into three groups, was performed. Copulations at the beginning of estrus (two copulas within the first 4 h after estrus; COP-1; n = 12), copulations around the middle of estrus (two copulas around 16 h after estrus; COP-2; n = 12), and noncopulations (only mounts) throughout the estrus period (control group; CON; n = 12) were performed. Estrus duration for CON group was 41.3 ± 8.2 h; for COP-1, it was 34.0 ± 5.3 h, and for COP-2, it was 39.7 ± 6.9 h (P = 0.04). Differences were detected between COP-1 and CON groups (P = 0.01) and between COP-1 and COP-2 groups (P = 0.05) but not between CON and COP-2 groups (P = 0.56). The LH peak time for the CON group was 20.0 ± 8.0 h; for the COP-1 group, it was 13.0 ± 3.6 h, and for the COP-2 group, it was 20.5 ± 5.8 h (P = 0.04). The COP-1 group was different than the COP-2 (P = 0.02) and CON groups (P = 0.03), and no differences were detected between these last two groups (P = 0.87). It was concluded that copulation reduced estrus duration and hastened the LH peak time only when performed during the beginning of estrus.

Factors affecting expression of estrus in dairy cows with high milk yields

The objectives of this study were to define the effect of the milk progesterone (P4) concentration on estrus expression in dairy cows with high milk yield and to identify the effect of milk yield and parity on the milk P4 concentration and cow’s pregnancy after artificial insemination (AI). In this study, 48 clinically healthy cows without reproduction disorders, on day 90-100 after calving were used. At the beginning of estrus and 12 hours after the beginning of estrus, the milk P4 concentration in dairy cows with high milk yield (group 3) was higher than in group 2 (33.66; 22.36%) and in group 1 (51.60; 65.26%) (P &amp;lt;0.001). The milk P4 concentration in the ≥3 lactation cows was higher than the second (13.45%; P&amp;gt;0.05) and the first (28.28%; P&amp;lt;0.01) lactation ones (28.28%; P&amp;lt;0.01). The milk P4 concentration at the beginning of estrus and 12 hours after the beginning of estrus in pregnant and non-pregnant cows was 2.58 and 3.32; 4.20 and 5.00 ng/ml, respectively (P&amp;lt;0.001). As a result, it was concluded that high progesterone concentration affected the expression of estrus and pregnancy results in dairy cows, and the measuring of progesterone concentration in milk can be used as a non-invasive method to provide detailed information about fertility in high milk yield cows..

Altrenogest treatment before weaning improves litter size in sows.

The study aimed to assess whether altrenogest treatment, fed before weaning (from -8 to -2days), could improve fertility of sows showing reproductive seasonality. Ninety sows (50 in winter-spring [WS] and 40 in summer-autumn [SA]) were randomly selected and assigned to control (C; 27 in WS and 20 in SA) or altrenogest treatment (A; 23 in WS and 20 in SA) groups. The diameter and number of ovarian follicles were transrectally scanned at the onset of oestrus. Oestrus was evaluated twice daily from weaning to day 8 post-weaning. Sows in oestrus were post-cervically inseminated at 0 and 24hr after the onset of oestrus with liquid stored semen (1.5×109 sperm/doses), and farrowing rates (FR) and total piglets born (LS) were recorded. More (p<.01) sows showed no signs of oestrus within 8days after weaning in SA (30%) than in WS (2%), without differences between A and C groups. The diameter (cm) of the follicles at the onset of oestrus was larger in A than in C sows (0.76±0.01 vs 0.73±0.01; p<.01), irrespective of the season. No differences in the number of follicles were found. FR did not differ between seasons and groups, being always above 85%. LS was larger (p<.01) in A (14.00±0.46) than C (12.27±0.44) sows, irrespective of the season. In conclusion, a short-term altrenogest treatment at the end of lactation improves the total number of piglets born from weaned sows, probably by promoting a better and more homogeneous follicular development at the start of oestrus.

Expression, Regulation, and Functional Characterization of FST Gene in Porcine Granulosa Cells

ABSTRACTProliferation, differentiation, and estrogen secretion of granulosa cells are the key factors affecting the estrous after weaning in sows. The objective of this study was to evaluate the expression of Follistatin (FST) in the ovary of Xiushui Hang and Duroc sows at weaning and estrus, the effect of FSH on transcript abundance of FST gene in granulosa cells and the role of FST gene in the weaning to estrus using siRNAs targeted to FST gene. In the present study, expression of the FST mRNA was evaluated by real time PCR. The FST mRNA levels showed a reduction from weaning to the estrus in both Xiushui Hang and Duroc sows, and the mRNA levels in Duroc ovary was higher than in Xiushui Hang sows at the beginning of estrus. Granulosa cells were obtained from the two largest follicles around follicular deviation, FST expression was decreased sharply after treatment with FSH (250 ng/ml). Knockdown of FST by siRNA in porcine granulosa cells significantly increased cell proliferation and estrogen secretion. These results indicate that FST gene is a negative regulator of follicle growth and function during the weaning-estrus interval.

The efficiency of vaginal temperature measurement for detection of estrus in Japanese Black cows

Recently, weak estrous behavior was assumed to be the cause of a decline in breeding efficiency in cattle. The present study investigated the effect of measuring the vaginal temperature on the detection of estrus in Japanese Black cows. First, the effect of hormone administration to cows with a functional corpus luteum on the vaginal temperature was evaluated by continuous measurement using a temperature data logger. After 24 h of cloprostenol (PG) treatment, the vaginal temperature was significantly lower than on day 7 after estrus, and the low values were maintained until the beginning of estrus (P < 0.05). The cows that received PG and exogenous progesterone (CIDR) did not show a temperature decrease until the CIDR was removed. This finding suggested that the vaginal temperature change reflected the progesterone concentration. The rate of detection of natural estrus was lower for a pedometer than for the vaginal temperature (P < 0.05); synchronization of estrus resulted in a high estrus detection rate regardless of the detection method. In a subsequent experiment, the effect of vaginal temperature measurement and the use of a pedometer on estrus detection was evaluated in the cool and hot seasons. The average activities during non-estrus and the activity increase ratio (estrus/non-estrus) changed according to season (P < 0.01, P < 0.05). However, the average vaginal temperatures during estrus and non-estrus were not affected by season. The estrus detection rate of the pedometer was lower in summer and lower than that obtained using the vaginal temperature. These results indicated that vaginal temperature measurement might be effective for detecting estrus regardless of estrous behavior.

An echographic study of follicular growth during induced estrus in female Azawak zebu in Niger.

An echographic study of follicular growth up to ovulation was carried out on 42 lactating Azawak cows (Bos indicus) after estrus induction by means of a PGF2α or a procedure involving the administration of progesterone vaginally (PRID® DELTA: progesterone-releasing intravaginal device) for a 10-day period and the injection of a PGF2α and an ECG (400 and 800 IU) on withdrawal. All the animals were inseminated 12 and 24 h after the onset of estrus. The percentage of estrus induced was not significantly different between the two groups of animals (81 %). The average time delay before the onset of estrus was significantly longer after injection of a PGF2α (84.8 ± 26.0 h) than after withdrawal of the PRID® (59.2 ± 5.8 h). The average duration of the estrus was significantly shorter after its induction by PGF2α (12.6 ± 2.6 h) than after induction by progesterone (22.9 ± 2.7 h). There was not a significant difference in the interval between the beginning of estrus and ovulation in animals treated by PGF2α (30.3 h) and progesterone (28.4 h). Injection of a PGF2α was accompanied by a significantly lower rate of gestation than that obtained after treatment of animals by progesterone (31.2 vs 54.5 %). These results confirm the necessity to adapt an insemination policy to hormonal treatment for estrus induction in B. indicus.

Improvement of Conception in Sheep Using Different Hormonal Treatments during Mating and their Influence on the Antioxidant Status

The objective of this study was to compare the effects of GnRH, prostaglandin F2α (PGF2α) and oxytocin treatments at the time of natural mating on the conception rate (CR) of non lactating pluriparous ewes. All ewes (n=61) were served naturally by fertile rams every 12 hours after the beginning of estrus. After natural mating, ewes were randomly assigned into four treatment groups; G1 received PGF2α (n=14); G2 received GnRH (n=12); G3received oxytocin (n=15) and G4 or control received placebo (n=20). Pregnancy diagnosis was performed 25 days post-insemination by transrectal ultrasonography. Ewes were bled at the day of mating and every 10 days till Day 50 post mating to determine the changes in the total antioxidants during the first third of pregnancy. Pregnancy rate was higher (P<0.05) for all the treatment groups (69.33%) compared with the control group (55.54%). Litter size did not differ between groups except for oxytocin group. Ewe lambs dominate male in this study and the sex ratio unexpectedly preferred them. Total antioxidants did not differ significantly between groups in the present study but they were at their lowest values during estrus in all the studied groups. Gestation length, birth weight, number of services, body weight did not affect the pregnancy rate. It could be concluded that treatments with GnRH and PGF and oxytocin at the time of service could improve conception rate in pluriparous ewes.

Treatment of queens in estrus and after estrus with a GnRH-agonist implant containing 4.7 mg deslorelin; hormonal response, duration of efficacy, and reversibility

Although slow release GnRH-agonist implants have been shown to effectively suppress the estrous cycle in queens, there are still several remaining questions about their use: if the probability and frequency of estrus induction because of initial stimulation is dependent on the stage of cycle when animals are treated, if all effects are reversible, and to what extent fertility is regained after the end of efficacy. The latter is of major interest to cat breeders who want temporary suppression of estrus in breeding animals. Twenty queens (14 with known fertility) were treated with a 4.7 mg deslorelin implant; hormonal changes (progesterone [P4], and estradiol [E2]) and behavioral changes with special respect to estrus signs and subsequent fertility were assessed. Group A cats (N = 10) were treated 3.2 ± 0.8 days after the beginning of estrus and estrus stopped 4.1 ± 2.5 days after treatment. Estrus induction was observed in one queen 6 days after treatment, and one queen showed estrous signs 138 and 155 days after treatment. Progesterone increased significantly after treatment in all animals until day 14, then slowly decreased reaching basal levels on day 56 without any further increase. Group B cats (N = 10) were treated 7 days after the end of estrus; nine cats had P4 > 1.5 ng/mL and basal E2, one cat (B10) had basal E2 and P4. In cat B10 estrus induction occurred after treatment, but in none of the others; however, E2 increased in all group B cats 1 day after treatment but reached pretreatment concentrations on Day 7 again and remained basal. The implant was still effective in one animal of the estrus group with a duration of efficacy >1102 days, in the others duration of efficacy varied between 483 and 1025 days. Eight queens were mated afterwards and gave birth to a healthy litter with 3.3 ± 1.5 kittens. This study proves that (1) the incidence of estrus induction—although very low—is highest after treatment in estrus or postestrus, (2) the duration of efficacy varies between 16 and 37 months, and (3) estrus suppression is reversible and animals remain fertile after the treatment effect has expired.