Appearance Of Estrus Research Articles

Factors and mechanisms influencing seasonal disorders in pig reproduction

The problem of unsatisfactory reproductive results in pigs is visible in a significant percentage of herds, especially during summer months and early autumn (seasonal summer infertility). This is reflected mainly in the reduced percentage of sows entering estrus after weaning and the effectiveness of mating/insemination. The consequence is a significantly lower number of births in November, December and sometimes even in January, compared to other seasons. There are many causes of seasonal summer infertility. The first things mentioned are usually the length of the light day and the high temperature in the pigs environment. An important reason that is not often discussed is the daily temperature fluctuations which usually occur at the end of summer and the beginning of autumn. Persistent unfavorable conditions are responsible for long-term stress. Hormonal disorders related to stress, leading to reproductive disorders, result from connections taking place in the hypothalamus between the hypothalamus-pituitary-gonadal axis (HPG), which regulates, among others, the reproductive functions of the ovaries, and the hypothalamus – pituitary – adrenal axis – HPA which governs organism reaction to stress. Under stressful conditions, glucocorticoids (cortisol, corticosterone) secreted in large amounts by the adrenal glands, as well as adrenaline, norepinephrine and, in small amounts, dopamine, may inhibit reproductive functions at the level of the hypothalamus, reducing the secretion of GnRH. At the same time, by reaching the pituitary gland, these hormones limit the sensitivity of the cells of this endocrine gland to GnRH. As a consequence, the maturation of follicles slows down, the number of ovulating and rupturing follicles decreases, and the secretion of estrogen is reduced. The consequence is the absence of heat or, more often, the so-called “silent heat”. Another problem is the uneven maturation of the follicles, which leads to a delayed appearance of estrus and its longer duration: 3-4 days. The final effect of these is a decrease in the rate of females presenting heat after weaning of piglets, a deterioration in the mating/insemination success rate, an increase in the rate of early abortions and percentage of litters with a small number of piglets in a litter. The summary stated that despite the identification of various seasonal causes of reproductive disorders in pigs, depending on both sows and boars, and the availability of various “tools” to reduce phenomenon of seasonal infertility, the presented problem has not been solved in a large percentage of swine farms. Its intensity varies and depends primarily on awareness, knowledge of ways to eliminate unfavorable conditions and determination in this regard. The first step, as always, is to objectively assess the situation. The assessment can be made through a detailed analysis of production data.

Effect of Selenomethionine or Yeast Enriched with Selenium on Reproductive Performance, Progesterone and Estrogen Hormones in Iraqi Ewes

This study was conducted at the animal farm affiliated with the college of agriculture, university of anbar, ramadi, iraq, to investigate the effects of selenomethionine or selenium-enriched yeast on the reproductive performance and hormone levels (progesterone and estrogen) in Iraqi ewes. the study was carried out from July 26, 2022, to january 27, 2023. eighteen ewes with an average age of 2-3 years and an average body weight of 43 ± 2.5 kg were used. the ewes were randomly divided into three equal groups, with six ewes in each group. all ewes were fed the same ration. group 1 served as the control group and received no treatment, while group 2 was treated with selenomethionine at a dose of 0.03 g/kg/bw. group 3 was treated with selenium-enriched yeast (saccharomyces cerevisiae-selenium) at the same dose, following the guidelines of the national research council (nrc, 1980). the treatments were administered orally for 45 days by dissolving the samples in 30 ml of distilled water. blood samples were collected from the jugular vein to assess changes in hormone concentrations. the results showed a significant increase in progesterone levels during the second period for groups 1 and 2 compared to group 3 (p ≤ 0.01). group 1 exhibited a significant increase in the time of the first appearance of estrus and the average time for estrus compared to group 2. group 2 showed a significant increase in estrus rate compared to group 1 and group 3. both group 2 and group 3 exhibited a significant increase in fertility rate, fertilization rate, pregnancy rate, and lambing rate. group 2 and group 3 also showed a significant increase in fecundity, twinning rate, and litter size compared to group 1. In conclusion, the supplementation of Selenomethionine and Selenium-enriched yeast positively affected reproductive performance in Iraqi ewes, as evidenced by improved hormone levels, estrus characteristics, fertility rates, and lambing outcomes.

Comparation of Physiology, Diameter of Ovary and Follicle at PO Cows Treated Different Method of Estrus Synchronization

One of the biotechnology reproductive used is estrus synchronization. This study determined the body’s physiological, estradiol level, and ovarian and follicle diameter in Peranakan Ongole (PO) cow estrus synchronization using modified progesterone-PGF2α and double injection of PGF2α. This study used 10 PO cows which were divided into two groups. Group 1, cows were given a modified intravaginal sponge containing 250 mg progesterone/sponge for 6 days, followed by intramuscularly injection of PGF2ɑ 25 mg/cow on day sixth. Appearance of estrus was observed on day 7th -9th. Group 2, cows were given a double injection 25 mg/cow of PGF2ɑ intramuscularly at 14-day intervals, then estrus was observed on day 15th -17th. The vaginal temperature was checked using a thermometer, the respiratory frequency was checked by inspection of thorax movements, and the pulse rate was checked by palpation of the coccygeal artery. Ovarian and Graafian follicle diameters were examined using ultrasonography. The data were analyzed using either T-Test or descriptive test. The results showed that in cows that were synchronized to estrus using combination of modified progesterone-PGF2ɑ and double injection of PGF2ɑ, the vaginal temperature, pulse rate, and respiration frequency were 36.9±0.98 and 37.34±0.83, 57.60±12.52 and 74.80±26.59, 30.40±10.43 and 20.00±2.83 respectively. There was no significant difference in ovarian and follicle diameter (P>0.05). The conclusion was the results of body physiology were in normal conditions but still below the average of cows undergoing estrus, and there were no significant differences in ovarian and Graafian follicle diameters.

Physiological role of seminal components in the reproductivetract of the female pig

Summary. In many species the appearance of oestrus is sufficient to ensure that the time of ejaculation, sperm transport and capacitation are balanced with the time of ovulation. In the pig these phenomena vary considerably and require additional regulatory mechanisms which are partly explained by seminal components.

Synchronization of GnRH and PGF2α on estrus response, pregnancy, progesterone hormones in crossing of Swamp Buffalo and Water Buffalo in West Sumatra, Indonesia

Abstract. Roza E, Aritonang SN, Susanti H, Sandra A. 2019. Synchronization of GnRH and PGF2α on estrus response, pregnancy, progesterone hormones in crossing of swamp buffalo and water buffalo in West Sumatra, Indonesia. Biodiversitas 20: 2910-2914. This study aims to determine the effect of GnRH and PGF2α synchronization on estrus emergence, pregnancy percentage, progesterone hormone levels and blood profile from artificial insemination (AI) of swamp and water buffalo crossing in Sijunjung, West Sumatra. The samples were 21 female swamp buffaloes with criteria clinically healthy, age ≥ 2.5 years and not pregnant. All buffalos on the first day were synchronized using 250 μgGnRH (Fertagyl®, Intervet International). All of the buffaloes received 12.5 μg PGF2α on the seventh day after GnRH injection. On the second day after injection of PG2α, the observation of estrus was carried out, the buffalos with estrus symptoms appeared after performing AI for 18 hours which the estrus symptoms was seen using a 0.5 ml Murrah buffalo semen with a sperm concentration of 500 million. Blood serum of 3-5 ml for the examination of progesterone levels was taken on days 21, 24, and 27 after appeared in AI. Hormone analysis was performed using the Enzyme-Linked Immunoabsorbent Assay (ELISA) method. The variables measured were the percentage of estrus, pregnancy, progesterone hormone levels, and blood profile. Pregnancy examination (PE) was carried out after 90 days in AI through rectal palpation. The data were analyzed descriptively. The results showed synchronization of GnRH and PG2α hormones in buffalo cattle which had 100% estrus, 66.67% pregnancy after AI, pregnant buffalo progesterone concentration 5.09-8.87 ng/mL and non-pregnant 1.11-3.45 ng/mL, total blood protein 7.9 g/L and blood glucose 86.86 mg/dL. The conclusion of this study is that the combination of GnRH and PG2α gives a clear appearance of estrus, progesterone hormone levels, and optimal buffalo blood profile.

FIELD EVALUATION OF ESTRUS SYNCHRONIZATION AND PREGNANCY DETECTION USING ULTRASONOGRAPHY TO THE LOCAL AWASSI EWES FOR SHEEP OWNERS IN KANAAN DISTRICT- DIYALA PROVINCE

The objective of this study was to carry out an on-farm experiment in sheep owner farms in Kanaan district for the period from 7th Feb. 2015 to 27th Mar. 2015 and to identify the unconventional methods in controlling the reproduction in sheep and increase their productivity using 45 local Awassi ewes, randomly selected from three sheep owners (15 ewes / owner). Treatment group (10 ewes/ owner) were treated with a vaginal sponges containing 20 mg fluorogestone acetate (FGA) inserted for 10 days, followed by I.M. injection of 500 IU equine chorionic gonadotropin (eCG), while 5 ewes / owner were regarded as control group without any treatment. Estrus was observed for all ewes for 5 days post withdrawal of sponges. Ewes that showed estrus were mated by rams in their flocks, thereafter, pregnancy detection was conducted at days 35-37 post- mating using transabdominal ultrasonography. A questionnaire involved 20 sheep owners and a demonstrative field day was conducted for owners contributed in the experiment, and others from the region of study to explain the importance and results of the experiment. The results showed the appearance of estrus in all ewes 100% within three days after the withdrawal of sponges. Pregnancy rate of 85.71% at days 35-37 of mating. The questionnaire showed there is an urgent need of knowledge for owners to find out the importance of controlling the reproductive cycle in sheep using vaginal sponges. Also, there were a correlation between the need of knowledge for sheep owners with (educational level for most of them, herd sizes, income from breeding, training courses and other activities in the fields of breeding and reproduction of sheep). In conclusion, the technology of estrus synchronization has an important role to improve reproductive performance of sheep and pregnancy could be detected through transabdominal ultrasonography at 35-37 days with high accuracy as well as there is great desire for the most owner to conduct estrus synchronization technique and to take care their birth of herds simultaneously.

Treatment of Ovarian Cysts in Buffaloes with Emphasis to Echotexture Analysis

The present study was conducted on 31 buffalo-cows aged 3-10 years and diagnosed rectally as they had follicular cyst. The previous diagnosis of the follicular cyst was confirmed by ultrasonography and serum progesterone assay. Ultrasound images of the ovarian follicles, both mature and cystic follicles, were individually identified and monitored and were subsequently digitized for computer analysis of echotexture [mean pixel value (MPV) and pixel heterogeneity (PH)] of the follicle antrum and wall. Animals were classified into two groups (Treated, n=20 and control, n=11). The treated buffalo-cows injected i.m with 100mg progesterone oily in nature followed by i.m injection of 5000 IU HCG at days 5. Out of the twenty treated animals 14 buffaloes responded and diagnosed as they had luteinized cyst. Out of the 14 animals that had luteinized cyst 9 buffaloes injected with 25 mg of PGF2α at day 14 and the other 5 buffaloes left as control. The 6 non responded buffaloes were classified into two subgroups each (n=3), one of them injected with HCG and the other left as control without any treatment. The time elapsed till luteinization of the follicular treated group was significantly different (32.67 ± 1.45 days and 15.71 ± 0.75 days respectively). The recovery rate was 27.27 % in control animals and 70% in treated ones. Days elapsed till appearance of estrus was significantly shorter in treated buffaloes (22.20 ± 1.19 days) in comparison to the control ones (56.33 ± 2.03 days). The conception rates were 33.33% and 66.67% in control and treated group respectively. Days elapsed from the treated animals (36.50 ± 1.47 days) compared to the control ones (64 days). Serum progesterone level was significantly different in treated animals comparing to the control ones. Changes in echotexture of bovine ovarian follicles assessed by computer analysis of ultrasound images has revealed a significant increase in echotexture parameters (MPV & PH) in cystic follicles compared with preovulatory follicles. PH of the antrum and wall of luteinized cystic follicles increased significantly compared to preovulatory and cystic follicles. Ultrasonography examination and echotexture analysis has revealed a presence of positive correlation between the cyst wall thickness and progesterone level which consequently aids in the treatment protocol. From the present study, it could be recommended that accurate diagnosis of the ovarian cyst was done by ultrasonography in combination with echotexture characteristics of ultrasound images together with progesterone profile 2 weeks postpartum early as soon as possible; and the animals should be re-examined with 7-10 days if possible for re-treatment of non responded cases if necessary.

A Novel Reproductive Peptide, Phoenixin

Normal anterior pituitary function is essential for fertility. Release from the gland of the reproductive hormones luteinising hormone and follicle-stimulating hormone is regulated primarily by hypothalamically-derived gonadotrophin-releasing hormone (GnRH), although other releasing factors (RF) have been postulated to exist. Using a bioinformatic approach, we have identified a novel peptide, phoenixin, that regulates pituitary gonadotrophin secretion by modulating the expression of the GnRH receptor, an action with physiologically relevant consequences. Compromise of phoenixin in vivo using small interfering RNA resulted in the delayed appearance of oestrus and a reduction in GnRH receptor expression in the pituitary. Phoenixin may represent a new class of hypothalamically-derived pituitary priming factors that sensitise the pituitary to the action of other RFs, rather than directly stimulating the fusion of secretary vesicles to pituitary membranes.

The pituitary-ovarian axis in dogs with remnant ovarian tissue

It can be difficult to confirm the presence of remnant ovarian tissue (ROT) in bitches that are presumed to be ovariohysterectomised. A GnRH stimulation test can be used to distinguish ovariectomised bitches from those in anoestrus, but it is uncertain whether the GnRH-induced changes in plasma LH and oestradiol concentrations that occur in intact bitches also occur in ROT-bitches. We report here eighteen ROT-bitches and compare the results of GnRH stimulation tests with those of six ovariectomised and six bitches in anoestrus. The basal (n = 17) and/or GnRH-stimulated (n = 18) plasma oestradiol concentration was above the detection limit of the assay, i.e., < 7 pmol/l, in all ROT-bitches but below the detection limit in all ovariectomised bitches. Basal plasma LH concentration was significantly higher in ROT-bitches (4.1 ± 0.7 μg/L) than those in anoestrus (0.64 ± 0.04 μg/L), and significantly lower than in ovariectomised bitches (20.2 ± 3.6 μg/L). Basal plasma LH concentration was relatively high in bitches in which there was a long interval between ovariectomy and appearance of oestrus. GnRH administration resulted in a significant increase in plasma LH and oestradiol concentrations in ROT-bitches. The GnRH-induced increase and subsequent decline in plasma LH concentration were significantly less in ROT-bitches than in either ovariectomised bitches or those in anoestrus. The GnRH-induced increase in plasma oestradiol concentration was significantly smaller in ROT-bitches than in those in anoestrus. In conclusion, the results of this study demonstrate that in dogs ROT is associated with noticeable changes in the pituitary-ovarian axis and suggest that a GnRH stimulation test may be used to distinguish between completely ovariectomised bitches and those with ROT.

The effect of embryo and maternal genotypes on prolificacy, intrauterine growth retardation and postnatal development of Nos3–knockout mice

Mice deficient for endothelial nitric oxide synthase (NOS3(-/-)) may represent a good model for studying embryo loss and intrauterine growth retardation caused by vascular deficiencies. We determined the effects of embryo genotype (homozygous vs. heterozygous descendants with paternal or maternal source of the non-functional NOS3 allele) and maternal environment (NOS3(-/-) vs. wild-type NOS3(+/+) females) on the appearance of estrus, fertility and prolificacy rates and live weight in the first week of life as well as phenotypic characteristics of offspring during the postnatal period. The results indicated that pregnancy outcomes and postnatal development of NOS3(-/-) mice seem to be related to deficiencies in fetal programming mainly determined by maternal genotype.

Comparative relations between progesterone blood concentration and appearance of oestrus in cows

The timely detection of oestrus presents an important professional procedure with which cattle farmers, in addition to veterinarians, are very often faced, because failure to detect oestrus poses a big economic problem. The objective of this work is to evaluate the efficacy of discovering oestrus in cows by determining the progesterone concentration (P4) in blood plasma. This experiment covered 22 animals, including 15 cows and 7 heifers, in which spontaneous oestrus was discovered. P4 concentration was determined using the ELISA test in samples of blood taken from the animals at the moment of insemination. Of the 15 cows, four cows (26.6%) were not inseminated at the optimal time, and the P4 level in these animals was higher than 1 ng/ml. All the heifers showed a progesterone concentration of over 1 ng/ml, and a percentage of conception which was 85%. The high P4 level in heifers at the moment of insemination could also be a consequence of stress caused by the regrouping and separating of the animals. Even though the heifers were under stress, which is indicated by the high progesteronemia values at the moment of insemination, the percentage of conception among them was beyond expectations. Therefore, the determination of P4 values at the moment of insemination is a suitable method for improving reproduction management on cattle farms. Inappropriate treatment of cows which are expected to show oestrus can cause stress and an increase in the values of the blood concentration of P4. On the grounds of the results obtained in this work, no negative influence of stress on the insemination results in heifers was observed.

Patterns of follicular growth in superovulated sheep and influence on endocrine and ovarian response.

Objectives of this study were to characterize patterns of follicular development in sheep superovulated with purified follicle stimulating hormone (FSH) (OVAGEN, ICP, Auckland, New Zealand) and to determine its influence on preovulatory events (onset of the oestrus behaviour and timing of the preovulatory luteinizing hormone surge) and ovarian response (ovulation rate and embryo yield). Number and size of all >/= 23 mm follicles from the first FSH injection to withdrawal of progestagen sponges was determined by transrectal ultrasonography just prior to every FSH injection in nine Manchega ewes superovulated with eight decreasing doses (ml) (1.5 x 3, 1.25 x 2 and 1 x 3) of OVAGEN injected twice daily from 60 h before to 24 h after the withdrawal of 40 mg fluorogestone acetate sponges. Oestrous detection and jugular blood sampling for LH radioimmunoassay were performed every 3 h from 14 to 53 h after sponge removal and ovulation rate and number of embryos were determined 4 days after progestagen withdrawal. Administration of OVAGEN induced a significant rise (p < 0.0005) in the number of follicles >/= 4 mm in size because of an increased growth in size of follicles from the first FSH injection to sponge removal, an increase in the number of newly detected follicles from 12 to 36 h of the first FSH dose (p < 0.005) and a decrease in regression rate from 24 h (p < 0.001). The number of follicles 2-3 mm in size at first FSH dose (10.4 +/- 1.5) was positively correlated with the number of >/= 4 mm follicles at 0 h (19.0 +/- 2.7, p < 0.01). A higher number of >/= 4 mm follicles at 0 h was related with an earlier appearance of oestrus (31.5 +/- 1.5 h, p = 0.08) and LH surge (45.0 +/- 2.3 h, p < 0.005), and a higher ovulation rate (18.2 +/- 3.8, p < 0.005). On the other hand, the rate of embryo recovery was decreased in ewes with earlier preovulatory LH peaks (p < 0.005), with a shorter interval between oestrus and LH peak (p < 0.05).

Use of vaginal electrical resistance (VER) to predict estrus and ovarian activity, its relationship with plasma progesterone and its use for insemination in buffaloes

In three experiments we studied the baseline and changes in VER during different natural estrous cycle stages (n=146) in ovarian structures and in plasma progesterone during estrus induced by prostaglandin injection (n=16) and the VER at insemination (n=90) in an attempt to predict estrus, ovulation and the best VER range for inseminating buffaloes for optimum conception. The baseline VER was classified on the basis of ovarian findings and estrous cycle stages. The mean VER during estrus, metestrus, diestrus, proestrus and anestrus was 32.68 ± 0.46, 41.26 ± 1.17, 50.23 ± 0.55, 43.20 ± 0.64 and 55.86 ± 0.57 ohms, respectively. There was a significant difference (P<0.01) between the VER except those between metestrus and proestrus. The ANOVA for VER over estrous cycle stages showed a highly significant (P<0.01) effect of stage of estrous cycle on VER in buffaloes. The percent decrease in VER was more pronounced from diestrus to estrus. In the second part of the study plasma progesterone profiles and the appearance of estrus in buffaloes induced to estrus using two dose schedules and routes of PGF 2α administration showed that luteolysis and estrus induction was slower in the 10 mg IVSM route (Intra Vulvo Submucosal) (only 60% animals evinced estrus in 48 to 72 hours) as compared to the 25 mg IM route (83.33% evidenced estrus in 48 to 72 hrs). Fall in plasma progesterone was synchronous to a fall in VER, the correlation (0.65) between them being positive and significant (P<0.01). After ovulation the VER started rising, showing a distinct relationship between VER and ovulation. By using VER, an additional 36.6% of the buffaloes could be detected in estrus. In the third part of the study, insemination of buffaloes induced to estrus (n=11) and normal-estrus buffaloes (n=79) showed that the overall conception rates to single insemination when the buffaloes were inseminated at the VER range of 26 to 30, 31 to 35 and 36 to 40 ohms were 81.48, 58.97 and 16.66%, respectively. Buffaloes showing VER from 31 to 35 ohms and 36 to 40 ohms also evidenced atypical and Null fern pattern in the cervicovaginal mucus. The study proved that VER can be used successfully to predict the stage of estrous cycle, ovarian status and ovulation; and insemination at a low VER distinctly improves the conception rates in buffaloes.

Plasma insulin-like growth factor-I concentrations increase during the estrous phase in goats

The objective of this study was to characterize plasma insulin-like growth factor-I (IGF-I) profiles during the estrous cycle in goats. Frequent blood samples were drawn during the day of estrus and during the luteal phase on Day 10 after estrus, and plasma growth hormone (GH) and IGF-I profiles were examined. Then, daily blood samples were drawn throughout the estrous cycle or during induction of estrus by prostaglandin F 2α (PGF 2α) to further clarify the IGF-I profiles. GH was secreted in an episodic manner in the estrous and luteal phases in goats. There were no significant differences in the mean concentrations, pulse amplitude and pulse frequency of GH between the estrous and luteal phases. IGF-I concentrations during estrous phase were higher than those in the luteal phase (P < 0.05). Plasma IGF-I increased approximately two days before behavioral estrus, and the IGF-I peak was observed in accordance with the appearance of estrus. The elevated IGF-I levels then declined to basal values 4 to 5 days after estrus. When estrus was induced by PGF 2α, plasma IGF-I concentrations increased after treatment, and the concentration 2 days after treatment (day of appearance of behavioral estrus) was significantly higher than concentrations before treatment (P < 0.05). The elevated IGF-I levels then declined during the 3 days after treatment. These results indicate that plasma IGF-I concentrations increase during estrus in goats.

Influence of food intake on plasma LH concentrations in multiparous sows

Nutrition may influence reproductive processes by a number of mechanisms including a direct effect on gonadotrophin secretion. The level of energy intake during lactation in multiparous sows may therefore have important consequences for luteinising hormone (LH) secretion after weaning. An experiment was carried out with 19 crossbred sows to investigate the effect of food intake in lactation and from weaning to day 6 post coitum on the pulsatile characteristics of LH on days 2 and 4 after weaning and on the preovulatory LH surge characteristics. During a 28 day lactation, sows were either offered 1.8 kg day −1 plus 0.55 kg per piglet suckled day −1 (H-high) of a commercial sow diet or 1.8 kg day −1 plus 0.25 kg per piglet suckled day −1 (L-low). After weaning, the sows from each lactation feeding regime were given either 1.5 kg day −1 (L-low) or 3.5 kg day −1 (H-high) until day 6 post weaning. The four treatment groups that comprised the 2 × 2 factorial design were thus HH, HL, LH and LL. Sows were mated at the appearance of oestrus. There were no significant differences between any of the treatment groups in episodic release of LH at either day 2 or day 4 post weaning. Also, there were no apparent effects of either food intake in lactation or between weaning and service on the timing and characteristics of the preovulatory surge of LH. The time intervals from the onset of the LH surge to peak LH concentrations for treatments LL, LH, HL and HH were 8.3 h, 8.7 h, 12.7 h and 11.3 h respectively and these differences approached significance ( P ⇒ 0.05). There were no significant correlations between liveweight loss during lactation and either the time to the onset of the LH surge or the time at which peak LH concentrations were observed.

Effect of a paramunity inducer on reproductive performance of gilts.

Optimal reproductive performance of gilts is an economically important characteristic which is influenced amongst others by the general health condition of the animal. In the present pilot study, we examined whether reproductive performance of gilts that were transported from a breeding to a commercial farm can be improved by paramunization, e.g. by enhancing the non-specific immunological response of the animal. Three groups of gilts were submitted to various treatments as follows. The first group received no treatment and served as the control group. The gilts of the second group were injected twice with a paramunity inducer derived from a sheep parapoxvirus (Baypamun liquid, Bayer, Germany), once 2 days before the transport and a second time 2 h before departure. The gilts of the third group were treated as those of the second group, but received an additional injection 2 days after their arrival at the commercial farm. Gilts were compared up to their first farrowing with regard to the appearance of oestrus, the number of the gilts which became pregnant, and the cost of supportive medication. Their litter size at farrowing, the number of piglets born alive and the litter weight have also been recorded. The results show that the number of gilts that showed oestrus and became pregnant was increased after Baypamun liquid treatment, particularly in the third group. The cost of supportive medication per gilt was much lower in treated groups compared to untreated animals. The treatment did not have a significant effect on the total number of piglets born, but some beneficial effect was seen in the number of piglets born alive and the average piglet weight at birth of gilts treated three times with Baypamun liquid. It was concluded that paramunization of gilts at the time of transport may improve their reproductive performance.

Histological changes in the uterus during postpartum in the mare.

An histological study of the postpartum period in 29 mares was carried out. Uterine biopsies were taken daily during the first 10 days postpartum in a total of 87 samples. At day 0, equine endometrium was characterized in the surface by the presence of regularly ordered microcaruncles; the stratum spongiosum was oedematous and contained distended and scarce glands. Degenerative changes in microcaruncles and endometrial glands were present on day 1 postpartum. The epithelium of the microcaruncles from 2 to 5 days postpartum showed cytoplasmic vacuolization, karyorrhexis and an inflammatory reaction with neutrophils and phagocitic cells. On day 7 postpartum, the histology of the endometrium was similar to the normal proestrus with cuboidal luminal epithelium and an oedematous stromal tissue. The changes are usually completed within days 9 and 10 postpartum with the histologically typical appearance of estrus in mares.

Embryo recovery from mares exposed to a year-to-year artificially prolonged daylength

The aim of the experiment was to determine the effect of a year-to-year prolonged daylength on the patterns of equine reproductive activity and results of embryo recovery. Experiments using Konik Polski mares were conducted over four reproduction seasons. Five mares were exposed to a regimen of artificially prolonged daylength (APD) and another five mares in a control group were kept under conditions of natural daylight. Both the control and experimental groups were examined for appearance of estrus, ovulation and also for the state of their coats. A single stallion was used for breeding all of the mares. The embryos were recovered nonsurgically 6 to 9 days after ovulation. All of the mares exposed to APD showed increased ovarian activity, which commenced earlier than in the control group. About 19% more ovulations were detected in the experimental group. The average number of ovulations per lighted mare per year was 15.3, while in the control group it was 12.4 ovulations (P<0.05). However, the embryo recovery rate and total number of embryos obtained from the mares exposed to APD did not exceed the number of embryos collected from the control mares (P<0.05). Modification of daylength had a visible effect on the mares by producing a change in their coats.

Delayed sexual maturation in the female rat during chronic exposure to delta-9-tetrahydrocannabinol

Δ-9-tetrahydrocannabinol (THC), the major psychoactive component of marihuana, retarded sexual maturation in the pubertal female rat as indicated by a delayed appearance of estrus and ovulation. Twice daily intraperitoneal injections of 10 mg THC/kg body weight from 27 days of age until the first day of full vaginal cornification delayed the onset of estrus and the occurrence of the first ovulation by an average of 4.3 ± 0.9 (S.E.M.) days in comparison with pair-fed, vehicle-treated animals (p<0.001). Ovulation during the first estrus occurred in 92% of the animals in each treatment group without a difference in the average number of ova ovulated. The delayed sexual maturation in animals treated with THC could not be attributed to reduced body weight gain since body weights in THC- and vehicle-treated groups were equivalent when vehicle-treated animals came into estrus. Delayed ovulation in THC-treated animals did not merely reflect the repeated blockage of ovulation from otherwise competent follicles in that the onset of vaginal cornification was delayed to a comparable extent. Rather, the data suggest retarded development of ovarian follicles, possibly as a result of pituitary suppression. It is noteworthy that, although delayed, both vaginal cornification and ovulation occured in spite of continued THC treatment, suggesting the development of drug tolerance.

Studies on the mechanism of nidation. XIX. Histochemical changes in the ovaries of pregnant rats following ergocornine.

Summary. When pregnant rats are given a single subcutaneous injection of ergocornine methanesulphonate on the 4th day of gestation, physiological indications of changes in the ovary are manifold. Activities of a number of histochemically demonstrable enzymes were investigated in the ovaries of ergot-treated pregnant rats. The enzymes included Δ5-3β-hydroxysteroid dehydrogenase, succinic dehydrogenase, alkaline and acid phosphatase and adenosine-triphosphatase. The ovaries were examined at 2-, 4-, 8- and 24-hr intervals after administration of the drug. Macroscopic and microscopic vascular dilatation and engorgement were seen in the ovaries at 2, 4 and 8 hr and had decreased by 24 hr. Activities of Δ5-3β-hydroxysteroid dehydrogenase and succinic dehydrogenase were histochemically demonstrable in the corpora lutea of gestation as well as other sites in the ovary at 2, 4 and 8 hr after ergocornine. At 24 hr, portions of the corpora lutea of gestation showed necrosis and dissolution of cells and many healthy vesicular follicles had developed. These changes in the ovary (luteolysis in the corpora lutea of gestation and development of follicles to the ovulation stage) form the basis for the physiological effects—interruption of gestation and appearance of oestrus—which occur 2 to 3 days after administration of ergocornine to pregnant rats during progestation.