Ovulation In Sows Research Articles

GnRH agonists: Updating fixed-time artificial insemination protocols in sows.

Protocols for fixed-time artificial insemination (FTAI) in swine reproduction can help increase genetic improvement and production efficiency. Different gonadotropin-releasing hormone (GnRH) agonists have been developed to gain better control of follicular development, timing, and ovulation quality; therefore, they have been extensively used in FTAI protocols. This literature review resumes the most important characteristics of the physiology of follicular development and ovulation in sows, followed by a discussion about the hormonal alternatives available to induce ovulation (human chorionic gonadotropin, hCG; porcine luteinizing hormone, LH and GnRH agonists). Also, ovulation induction failures with GnRH agonists are described. Finally, current FTAI protocols with GnRH agonists are resumed and discussed. FTAI with GnRH agonists has proven to be an efficient, successful reproductive protocol that can be implemented in pig farms due to better knowledge of an endocrine system that regulates follicular development and ovulation and increased availability of several GnRH agonists that allow more efficient reproductive swine programs.

Hypothalamic-Pituitary-Adrenal Hormones Impair Pig Fertilization and Preimplantation Embryo Development via Inducing Oviductal Epithelial Apoptosis: An In Vitro Study.

Previous studies show that stressful events after ovulation in sows significantly impaired the embryo cleavage with a significant elevation of blood cortisol. However, the effects of corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH) and cortisol on fertilization and embryo development remain to be specified, and whether they damage pig embryos directly or indirectly is unclear. This study demonstrated that embryo development was unaffected when pig parthenotes were cultured with different concentrations of CRH/ACTH/cortisol. However, embryo development was significantly impaired when the embryos were cocultured with pig oviductal epithelial cells (OECs) in the presence of CRH/cortisol or cultured in medium that was conditioned with CRH/cortisol-pretreated OECs (CRH/cortisol-CM). Fertilization in CRH/cortisol-CM significantly increased the rates of polyspermy. CRH and cortisol induced apoptosis of OECs through FAS and TNFα signaling. The apoptotic OECs produced less growth factors but more FASL and TNFα, which induced apoptosis in embryos. Pig embryos were not sensitive to CRH because they expressed no CRH receptor but the CRH-binding protein, and they were tolerant to cortisol because they expressed more 11-beta hydroxysteroid dehydrogenase 2 (HSD11B2) than HSD11B1. When used at a stress-induced physiological concentration, while culture with either CRH or cortisol alone showed no effect, culture with both significantly increased apoptosis in OECs. In conclusion, CRH and cortisol impair pig fertilization and preimplantation embryo development indirectly by inducing OEC apoptosis via the activation of the FAS and TNFα systems. ACTH did not show any detrimental effect on pig embryos, nor OECs.

Relations between the time of ovulation and fecal estrogen concentration in sows

Artificial insemination (AI) is the most important biotechnology in pig reproduction. To achieve the best possible fertility results, appropriate timing of the insemination is essential. The optimal time for AI is 12 h before to 4 h after ovulation. This time-frame, unlike in estrus, is not recognizable through external indicators. It would, therefore, be beneficial to find simple and economical methods that support manual estrus checks and are able to determine the time of ovulation more accurately. On this basis, starting 80 h after weaning, 14 DanBred sows (parity: 5.2 ± 2.4) were checked for ovulation via ultrasound scans every 8 h over a period of 72 h. Additionally, rectal fecal samples were taken and analyzed for their estrogen concentration to assess possible relations to ovulation time. On average, sows ovulated 121 ± 10 h after weaning and 16 ± 9 h after onset of heat. There was a prominent drop in fecal estrogen levels 4 h before ovulation when compared to almost all other points in time (before ovulation: 20 h (P = 0.056), 12 h (P = 0.006); after ovulation: 4 h and 12 h (P < 0.001)). There are, however, significant differences in the sow-individual fecal estrogen concentrations for which several influencing factors must be considered.

Time of ovulation in sows is not related to intravaginal dissolved oxygen levels or temperature

Timing is a crucial factor in the success of artificial insemination (AI). In sows, the appropriate time for AI amounts 12 hours before to 4 hours after ovulation based on the period in which viable spermatozoa should be available at the site of fertilization. However, in contrast to the general period of estrus, which is associated with behavioral and physical changes, the exact time of ovulation is not visible externally. It is, therefore, important to consider and evaluate additional methods that allow a more accurate determination or prediction of the actual time of ovulation than just the occurrence of the standing reflex in sows. With this goal in mind, 14 DanBred sows (parity: 5.2 ± 2.4) were subjected to ultrasound scans of the ovaries. The examinations started 80 hours after weaning and were repeated in 8 hours intervals for up to 72 hours to monitor ovarian function and time of ovulation. Additionally, intravaginal dissolved oxygen (pO2 in mmHg) levels and temperature (in°C) were measured using a fluorescence-based technique (OxyLiteTM) to uncover possible relations between the time of ovulation and the amount of oxygen available to cells and tissue. On average, sows ovulated 121 ± 10 hours after weaning and 16 ± 9 hours (mean ± SD) after the onset of heat. There were no significant differences in the intravaginal pO2 (P=0.988) or temperature (P=0.985) between the time points and in any of the direct, pair-wise comparisons between the five respective time points (P>0.05; before ovulation: 20 hours, 12 hours, and 4 hours; after ovulation: 4 hours and 12 hours). In conclusion, intravaginal pO2 and temperature have limited usefulness in predicting the occurrence of ovulation in sows using the presented technology.

Equine chorionic gonadotropin pretreatment 15 days before fixed-time artificial insemination improves the reproductive performance of replacement gilts

Fixed-time artificial insemination (FTAI) technology uses exogenous reproductive hormones to regulate the sexual cycle and ovulation of sows without oestrus identification, which improves the sow breeding utilisation rate, reduces the number of non-productive days, and elevates the efficiency of pig farm management. In this study, we aimed to optimise FTAI procedures. Healthy 190-day-old and about 90 kg Large White × Landrace crossing breed replacement gilts (n = 166) which were of unknown reproductive status were randomly selected and divided into three groups: a control group (n = 62), an eCG-15D group in which the gilts were pretreated with equine chorionic gonadotropin (eCG) injection 15 days before starting FTAI (n = 50), and an eCG-20D group pretreated with eCG injection 20 days before starting FTAI (n = 54). All three groups were then subjected to the same conventional FTAI procedure. Pigs were orally administered Altrenogest (ALT, 20 mg per pig per day) for 18 days and then 42 h after ALT feeding was stopped, they were injected with 1 000 IU eCG followed by 100 μg GnRH 80 h later. The gilts were inseminated for the first time 24 h after gonadotropin-releasing hormone (GnRH) injection and then again 16 h later. After 42 h of ALT feeding, gilts in the eCG-15D group displayed a higher follicular diameter until artificial insemination (AI) than those from the other groups (P < 0.05). In addition, the ovulation times were the most synchronised in the eCG-15D group, with 100% of the gilts ovulating before the second AI on day 25 of FTAI. Furthermore, the gilts in the eCG-15D group achieved the highest pregnancy rate (92%), farrowing rate (90%), total pigs born (11.59), and pigs born alive (11.18). Together, the findings of this study demonstrate that reproductive performance can be optimised by pretreating gilts with eCG 15 days before conventional FTAI.

НОВІТНІ БІОТЕХНОЛОГІЇ ВІДТВОРЕННЯ СВИНЕЙ В УМОВАХ ПРОМИСЛОВОГО СВИНАРСТВА

Висвітлено сучасне розуміння ефективності новітніх методів біотехнології відтворення свиней, які спрямовані на зменшення впливу негативних факторів промислового свинарства. Проаналізовано вплив стрес- факторів на репродуктивну здатність свиней та визначені ефективні способи за-побігання гальмуванню відтворювальної функції. Встановлено, що отримання високопродуктивних нащадків розпочинається з формування біологічно повноцінних гамет і нормального їх злиття, яке досягається завдяки застосуванню методу штучного осіменіння. Виявлено, що використання внутрішньоматкового методу дає змогу осіменяти свиноматок малими спермодозами, збільшуючи при цьому кількість запліднених свиноматок (відсоток заплідненості). З метою довготривалого зберігання генофонду високоцінних кнурів-плідників використовують метод кріоконсервації сперміїв. Успіхи від використання цього методу насамперед залежать від складу розріджувачів та програм заморожування, де перспективним залишається використання спермальної плазми та кріопротек-торів нового покоління. З’ясовано, що ефективна інтенсифікація відтворної здатності свиней мож-лива лише в разі застосуванні біотехнологічних прийомів ‒ стимуляції й синхронізації охоти та ову-ляції у свиноматок, що базуються на закономірностях зміни гормонального профілю залежно від їх фізіологічного стану. Для цього використовують біологічно активні речовини та фармакологічні засоби (гормональні препарати та комплекси вітамінів). Встановлено, що для забезпечення ритміч-ності виробництва свинини через синхронізацію опоросів використовують простагландини. Викори-стання методів синхронізації опоросів дозволяє, без шкоди для поросят і свиноматок, регулювати тривалість поросності, скоротити кількість мертвонародженого молодняка, зменшити вікові розбіжності між ними, витримувати крок ритму виробництва та звести до мінімуму трудові вит-рати. Визначено, що раннє та своєчасне відлучення поросят дає можливість підвищити інтенсив-ність використання свиноматок, знизити виснаженість організму та уникнути затримки статевої охоти. З метою зниження негативних факторів у період відлучення перспективним є використання підгодівлі поросят вітамінами антиоксидантної дії (вітаміни А,Е,С) та Селеном у вигляді кормових добавок, що підвищує функціональний стан печінки, резистентність організму та в подальшому скорочує період їх вирощування до забійних кондицій.

Ovulation and fertility responses for sows receiving once daily boar exposure after weaning and OvuGel® followed by a single fixed time post cervical artificial insemination

Boar exposure is used to stimulate follicle development and estrus in sows after weaning and also to improve semen uptake and sperm transport with insemination. However, the need and value of boar exposure is uncertain when ovulation induction is used. These studies were designed to determine the effect of daily boar exposure after weaning when used with ovulation induction and fixed time post-cervical artificial insemination (PCAI). In experiment 1, sows were weaned into stalls and assigned to receive 3 min of daily fenceline boar exposure (BE, n = 7) or no boar exposure (NBE, n = 8). All sows received OvuGel at 96 h after weaning and BE or NBE 30 min prior to a single PCAI 24 h after OvuGel. Ovaries were assessed daily for follicle size from weaning until ovulation. Cervical contractions were measured 30 min following BE or NBE and before PCAI, while uterine contractions were measured for 1 h following PCAI. In experiment 2, weaned sows (n = 244) were assigned by parity to receive once daily BE for 1.5 min each day or NBE. OvuGel, PCAI and ultrasound methods were performed similarly as in experiment 1. Results from experiment 1 indicated BE did not significantly influence follicle size or measures of fertility. However, BE did increase the frequency of cervical contractions (P < 0.05), but with no effect on the uterus. Results from experiment 2 indicated BE had no effect on catheter passage for PCAI but did increase the proportion of sows ovulating within 48 h after OvuGel (77.7 vs 67.5%, P = 0.05), and tended (P = 0.10) to increase the proportion of sows inseminated 24 h before ovulation (70.3 vs. 61.0%). However, BE had no effect on adjusted farrowing rate (84.4 vs. 77.4%) or total pigs born (13.2 vs. 12.5) for BE and NBE, respectively. There were treatment and parity interactions for follicle size at time of OvuGel and at time of PCAI (P < 0.05) with BE minimizing parity effects on follicle size. Parity effects were also evident on farrowing rate and litter size when inseminations occurred >24 h from ovulation but not when inseminations occurred ≤24 h before ovulation. The results indicate that boar exposure for only minutes each day after weaning had beneficial effects for improving follicle development, ovulation induction, and AI timing, most notably in parity 1 sows, but had no beneficial or detrimental effects on the ability to perform PCAI.

Effect of dosage and duration of altrenogest treatmenton follicular development and ovulation in sows*

The aim of this study was to investigate the effect of altrenogest (ALT) treatment on follicular development and ovulation in sows. Sows (parity 6-9; D0: weaning day) were assigned to four treatments as follows: control (no ALT treatment; n = 20), ALT-4-0 (ALT 20 mg/day, 5 days; D-4-D0; n = 20), ALT-4-2 (ALT 20 mg/day, 7 days; D-4-D2; n = 23), and 2ALT-4-2 (ALT 20 mg twice a day [40 mg/day], 7 days; D-4-D2; n = 24). The sows in each group were further divided into three groups based on slaughter periods: day 1 (DF1) and day 4 (DF4) of the follicular phase, and after the initiation of estrus. The number of follicles was reduced on DF4 compared to DF1 (P < 0.001). On DF1, follicular size (FS) of the control was larger than that of ALT-4-0, ALT-4-2, and 2ALT-4-2, but on DF4, FS of ALT-4-2 and 2ALT-4-2 was larger than that of the control and ALT-4-0 (P < 0.001). The coefficient of variation of FS on DF4 was smaller in ALT-4-2 compared to the control and 2ALT-4-2 (P < 0.05). Ovulation rate was similar between groups (P - 0.05). ALT improved follicular growth and the homogeneity of FS without affecting ovulation.

Predicting oestrus and ovulation in sows using the vulva, cervical mucus and body temperature

Predicting oestrus and ovulation in sows using the vulva, cervical mucus and body temperature

Indução da ovulação e características ovarianas de marrãs pre-púberes tratadas com gonadotrofina coriônica humana ou kisspeptina

In view of its similar structure and function to luteinizing hormone (LH), human chorionic gonadotropin (hCG) has conventionally been used as the main hormone to induce estrus and ovulation in sows. Recently, it has been demonstrated that the neuropeptide kisspeptin is associated with pituitary LH release in different mammalian species, including swine. Thus, the aim of this study was to determine whether kisspeptin-10 combined with equine chorionic gonadotropin (eCG) could be an efficient method to induce ovulation in prepubertal gilts. Thirty 5-month-old gilts weighing 78.0 ± 8.4 kg were randomly divided into five groups of six animals each. Groups 1, 2 and 3 received 750 IU eCG, while groups 4 and 5 received saline solution. After 72 hours, the animals received 380 nmol kisspeptin-10 (group 2), 500 IU hCG (groups 3 and 4), or saline (groups 1 and 5). The treatments were applied by a single intramuscular injection. The animals were slaughtered 7 days later and ovulation was confirmed by the presence of corpora lutea in the recovered ovaries. Data were analyzed by the Kruskal-Wallis and Fisher exact tests. The number of gilts that ovulated was similar in groups 2 and 3. This number was higher in group 5 (P<0.01) and in groups 1 and 4 (P=0.08). The weight or size of the ovaries was not influenced by the treatments, although the number of ovulations was higher in groups 2 and 3 (P<0.01). These results suggest that kisspeptin-10 and hCG have similar biological activity to induce ovulation in prepubertal gilts.

Postpartum injection of human chorionic gonadotrophin: Effects on sow ovarian follicles

Sows received 1000 IU human chorionic gonadotrophin at 24 or 48 hours after farrowing or served as controls. Ovaries were examined ultrasonically at 0, 24, 48, 72, 96, and 120 hours. No sows ovulated by 120 hours, although corpora lutea at 10 days indicated a later ovulation in some sows.

Fertilisation rate obtained with frozen-thawed boar semen supplemented with rosmarinic acid using a single insemination timed according to vulvar skin temperature changes.

Artificial insemination (AI) of sows with frozen-thawed semen usually results in lower pregnancy rates and litter sizes than the use of liquid preserved semen. The present study evaluated the effectiveness of vulvar skin temperature changes as a predictor of ovulation in sows and determined the fertility rates obtained after AI with frozen-thawed semen supplemented with rosmarinic acid (RA). Semen was collected from mature boars and cryopreserved in experimental extenders supplemented with or without 105 μM of RA. Multiparous sows were inseminated with a single dose of semen when vulvar skin temperature decreased to a value below 35 °C. Intrauterine insemination was performed using 1.5 × 109 spermatozoa. The sows were slaughtered 48 h after AI and the embryos and oocytes were recovered from the oviducts. Total and progressive motility, viability and acrosome integrity were significantly (P < 0.05) higher in RA-supplemented semen samples compared with the control. Fertilisation occurred in all sows inseminated in the study, although there were no significant differences between the experimental groups. Sows inseminated with RA-supplemented semen showed a slight increase in the number of embryos recovered as compared to sows inseminated with control semen. In conclusion, insemination according to vulvar skin temperature changes resulted in successful fertilisation in all sows, although supplementation of the freezing media with RA did not improve the fertilising ability of frozen-thawed boar sperm.

Highlights on Artificial Insemination (AI) Technology in the Pigs

Abstract Over the past decade, there has been a tremendous increase in the development of field AI services in the majority of countries concerned with pig production. The objective of this paper is to review: (a) the current status of swine AI in the world, (b) significance and limitation of AI with liquid and frozen semen, (c) the biological traits of porcine semen in relation to in vitro sperm storage, (d) the criteria used for selection of a boar stud as a semen supplier, (e) how to process boar semen for liquid and frozen storage in the commercial settings and (f) how to improve fertility and prolificacy of boar semen. More than 99% of the inseminations conducted worldwide are made with liquid-stored semen. AI with frozen semen is used only for upgrading the genetic base in a particular country or herd. Determining the initial quality of semen ejaculates along with the selection of the optimum storage extender has a profound effect on the quality and fertility of AI doses. Different procedures have been used for improving the fertility of preserved spermatozoa including colloidal centrifugation of the semen, intrauterine insemination and modulation of the uterine defense mechanism after AI. Development of an efficient protocol for synchronizing the time of ovulation in sows and gilts coupled with improving uterine horn insemination technique will make a breakthrough in the commercial use of frozen boar semen.

Synchronization of ovulation and fertility in weaned sows treated with intravaginal triptorelin is influenced by timing of administration and follicle size

A 100 μg dose of triptorelin was tested for synchronizing ovulation in sows. In Experiment 1, conducted in April through June, sows (n = 125) were assigned to Control (untreated), TG-96 (Triptorelin Gel (TG) given intravaginally at 96 h post-weaning), or TG-E (given intravaginally at estrus). To optimize AI timing, sows were inseminated at 2 and 26 h after estrus for Control and TG-E and at 8 and 32 h following TG-96. Ovulation by 48 h post-treatment tended to be affected by treatment (P = 0.08) and more (P < 0.05) TG-96 sows ovulated (57.9%) compared to Controls (34.2%), but TG-E (45.1%) did not differ (P > 0.10). Duration of estrus was reduced (P < 0.005) in TG-96 (51 h) and TG-E (58 h) compared to Controls (65 h). There was no treatment effect on farrowing rate (71%) or total born (10.4). Average follicle size <6.5 mm at 96 h after weaning was associated with reduced (P < 0.01) estrus, ovulation and farrowing rate. Experiment 2 was conducted in August through September using 503 weaned sows. The TG-96 treatment reduced duration of estrus (P = 0.03), but treatment did not affect estrus expression, farrowing rate or total pigs born. In conclusion, use of a 100 μg dose of triptorelin intravaginally at 96 h or at estrus advanced ovulation and when used with timed insemination, resulted in similar farrowing rates and litter sizes comparable to sows mated based on estrus. However, ovulation induction and timed AI success may benefit from an approach that ensures sows have adequate follicle development at time of treatment.

Induction and synchronization of ovulations of nulliparous and multiparous sows with an injection of gonadotropin-releasing hormone agonist (Receptal)

The objective of this study was to determine if administration of a set dose (10 μg) of a gonadotropin-releasing hormone agonist, buserelin (Receptal; Rc), at set times after altrenogest (Regumate; RU) treatment or after weaning was able to induce and synchronize ovulation in female swine (gilts and sows). The pubertal (n = 187) gilts were allocated to four groups, all synchronized with RU. Group 1 (RU) was inseminated twice at detected estrus, Group 2 (RU+Rc120) and Group 4 (RU+Rc104) received 10 μg Rc at 120 or 104 h after the end of RU treatment, respectively, and Group 3 (RU+eCG+Rc104) was treated with 800 IU equine chorionic gonadotropin (eCG) at 24 h and Rc 104 h after the end of RU treatment, respectively. Gilts were inseminated twice at predetermined times, namely 144 and 168 h (Group 2), 128 and 144 h (Group 3), and 144 and 152 h (Group 4) after the end of RU treatment, respectively. Pregnant gilts were slaughtered at 30 d. Administration of Rc 104 h after the end of RU feeding synchronized ovulation over a 24-h time window in 97.9% and 100% of the gilts of Groups 3 and 4, respectively, whereas Rc administration at 120 h (Group 2) only successfully synchronized 88.9% of the gilts over 24 h. Ovulation rates of gilts of Groups 2 and 4 were similar to that of the control group. Pregnancy rates were numerically higher in Groups 2 and 3 (92% and 96%, respectively) compared with those of Groups 1 and 4 (84% and 81%, respectively). Combination of eCG with Rc administration at 104 h (Group 3) increased ovulation rate (+4 CL) but decreased embryo survival to 62% at Day 30. The weaned sow experiment involved 61 sows of a range of parities (2.7 ± 0.9), allocated to two control groups (Control 104 group and Control 94 group) and two treated groups (Rc104 group and Rc94 group), which received 10 μg Rc at 104 and 94 h after weaning, respectively. The females were inseminated at detected estrus. All pregnant sows farrowed. After treatment with Rc 94 h after weaning, 100% of sows ovulated over a 24-h time window versus only 68.7% of controls. Farrowing rate and litter size of the sows treated with Rc at that time were unaffected compared with that of control sows. In contrast, Rc administration at 104 h after weaning may have been too late; only 66.7% of the treated sows ovulated during a 24-h period. This proportion was numerically lower but not significantly different than that for control sows. Farrowing rate and litter size of treated sows were not significantly different than that of controls. Administration of Rc at the dose and times selected in this study tightened synchrony of ovulation in gilts and in sows after weaning. It remains to be established if such a synchrony is suitable to obtain good fertility after a single artificial insemination at a predetermined time.

LH and FSH secretion, follicle development and oestradiol in sows ovulating or failing to ovulate in an intermittent suckling regimen

The present paper describes LH and FSH secretion, follicle development and ovulation in sows that were subjected to a limited nursing regimen. From Day 14 of lactation, 32 sows were separated from their piglets for 12 h every day (intermittent suckling; IS). Half the sows had boar contact during separation. Nine of 32 sows ovulated spontaneously within 14 days from initiation of IS. The frequency of LH pulses on the first day of IS tended to be higher in anovulatory sows (6.3 v. 4.2 pulses per 12 h; P < 0.10); other characteristics of LH secretion were similar to sows that ovulated. The characteristics of FSH secretion did not differ over the 8-h sampling period. Boar contact did not influence either LH and FSH secretion or the number of sows that ovulated. Up to 58% of anovulatory sows showed an increase in follicle size after initiation of IS and, 4 days after the initiation of IS, one-third still had follicles similar in size to those in ovulatory sows. However, the oestradiol concentration in anovulatory sows did not increase. We conclude that FSH and LH stimulation in anovulatory sows is not limiting for normal follicle development, but that ovarian follicles are not responsive to increased LH secretion.

Decreased follicular size during late lactation caused by treatment with charcoal-treated follicular fluid delays onset of estrus and ovulation after weaning in sows1

The weaning to estrus and weaning to ovulation intervals in sows are controlled by ovarian follicular growth after weaning. Longer intervals could be caused by smaller diameter follicles at weaning that take more time to reach a preovulatory size. We addressed this hypothesis by decreasing the diameter of follicular populations before weaning and then measuring follicular development and interval to estrus and ovulation after weaning. The posterior vena cava, cranial to the entry of the ovarian vein, was cathetered for blood sampling and infusion in 20 sows at 12 +/- 1 d after farrowing. Sows were assigned randomly to receive either 30 mL of charcoal-treated follicular fluid (FF, n = 9; a treatment known to decrease serum FSH and follicular diameter) or 30 mL of saline (n = 11) by venous infusion thrice daily (0700, 1500, and 2300 h) for 96 h beginning at 14 +/- 1 d after farrowing. Sows were weaned 48 h after the last infusion. Blood samples were collected for FSH analysis thrice daily beginning on the day of catheterization and continuing until ovulation. Follicular diameter was determined once daily by transrectal ultrasonography. A treatment x time interaction was detected for serum FSH (P < 0.001) and follicular diameter (P < 0.001) because serum FSH and the diameter of follicular populations decreased in FF sows during the infusion period. After the infusion period, serum FSH rebounded in FF sows, and follicles resumed growth but grew at the same rate as those of saline-treated sows, thus failing to achieve equivalent diameters relative to saline-treated sows on a given day after weaning. As a result, sows treated with FF had longer (P < 0.05) weaning to estrus (6.1 +/- 0.4 d) and weaning to ovulation (8.6 +/- 0.5 d) intervals compared with saline-treated sows (4.7 +/- 0.4 d and 7.2 +/- 0.4 d, respectively). We conclude that the diameter of the follicular population at weaning is one factor that controls interval to estrus and ovulation in sows. Small follicles at weaning cannot undergo compensatory growth and require additional time to reach a preovulatory size.

Synchronization of estrus and ovulation in sows not conceiving in a scheduled fixed-time insemination program

A field study was conducted to investigate the effectiveness of a treatment with altrenogest, eCG and hCG or the GnRH-analogue D-Phe 6-LHRH to synchronize estrus and ovulation of sows diagnosed as non-pregnant in order to reintegrate them back into a scheduled fixed-time insemination program. Sows ( n = 531) diagnosed as non-pregnant by ultrasonography on days 21–35 after insemination were subjected to one of three treatments: (1) 16 mg altrenogest/day/animal orally for 15 days to block follicular growth, followed by injection of 1000 IU eCG intramuscularly (i.m.) 24 h after withdrawal of altrenogest to stimulate follicular growth and 500 IU hCG i.m. 78–80 h after eCG to induce ovulation; (2) similar to (1) except that 20 mg altrenogest and 800 IU eCG were used and (3) similar to (2) except that 50 μg D-Phe 6-LHRH was used to induce ovulation. Females were artificially inseminated (AI) twice at 24 and 40 h, respectively, after hCG/D-Phe 6-LHRH. Success of treatments was checked by ultrasonography of the ovaries. Rates of conception and farrowing (CR, FR), and number of total and live born piglets (TB, LB) were recorded and compared to those of synchronized first served sows. Females had differing ovarian structures prior to treatment. Altrenogest effectively blocked follicular growth in >80% of the females irrespective of dosage, but 16 mg increased the development of polycystic ovarian degeneration. Four to 18% of the females still had corpora lutea after altrenogest. Most females ovulated either between both inseminations or thereafter ( P < 0.05). Females treated with D-Phe 6-LHRH tended to ovulate earlier than those injected with hCG. The CR and FR were up to 25% lower for sows diagnosed as non-pregnant than for sows after first service ( P < 0.05). Among sows diagnosed as non-pregnant the CR was higher in females treated with D-Phe 6-LHRH ( P < 0.05). No differences were found in regard to numbers of TB and LB. In conclusion, a treatment with 20 mg altrenogest per day per animal, followed by 800 IU eCG and 50 μg the GnRH-analogue D-Phe 6-LHRH is appropriate to synchronize estrus and ovulation of sows diagnosed as non-pregnant. Whether there might be a need to feed altrenogest for a longer interval of 18 days has to be investigated.

Influence of CRH and ACTH administration on endocrine profile and ovulation in sows.

Grouping of sows is a stressful event until the ranking is established. The purpose of this study was to simulate stress by repeated administration of porcine corticotropin releasing hormone (CRH) and adrenocorticotropic hormone (ACTH)/tetracosactide and to study its influence on endocrine profile and ovulation. Four multiparous sows were used and blood was collected every 2 h from the onset of pro-oestrus until 12 h after ovulation. The first oestrus after weaning was used to check ovulation and acclimate the sows to their environment. The second oestrus after weaning was used as control. At their third oestrus CRH (0.6 microg/kg) and at their fourth oestrus ACTH (5 microg/kg) were given every 4 h from onset of oestrus until ovulation. The total 'area under the curve' of cortisol was twofold larger in two of four sows during the CRH treatment period, and two- to fourfold larger (p < or = 0.05) during the ACTH treatment period, compared with the corresponding control period. In three sows, there was no clear effect of either CRH or ACTH on the levels of oestradiol 17beta, luteinizing hormone (LH) or on the timing of ovulation. One sow was different in all hormonal patterns and also in the timing of ovulation. In all four sows, ACTH treatment lowered the baseline level of prostaglandin F(2 alpha)-metabolite. Therefore, we conclude that stage of the oestrous cycle seems to be of importance when investigating the influence of exogenous administration of CRH/ACTH on hormonal pattern and ovulation time in the sow.

Biotechnische Fortpflanzungssteuerung bei Sauen und mögliche verdeckte Genfrequenzänderung für das Brunstverhalten

Abstract. Title of the paper: Biotechnical control of reproduction in sows and the opportunity of a hidden change of gene frequency for estrous behaviour Since more than three decades hormones have been used for the synchronisation of ovulation in sows often combined with timed artificial insemination. This will be done without considering the estrous behaviour. A selection with regard to symptoms of standing behaviour is not necessary. Regarding to that it is possible to breed pigs that are not suitable for that purpose. The aim of this study was to examine the opportunity of hidden gene frequency changes in the genetics of pigs in two herds of German Landrace. This will be shown by the example of the standing behaviour and especially the time they need to come in heat after weaning of the piglets. The basic datas was provided by two pig-breeding farms. The calculation is based only on the information to the 2nd and 3rd litter of these sows in order to reduce the influence of selection. It is assumed that the path of heredity is monofacturial. Only pigs with the genotype “aa” will be negatively affected. At the beginning the father of boars (SS) is the sole carrier of the defect gene. The gene frequency, frequency for homozygotes and the correct number of concerned pigs after 10 generations will be calculated for a more accurate description of the expansion of this gene. The gene frequency results in the balance of 0.4 %. This figure has already been achieved after eight generations. According to this value the frequency of homozygotes is 0.0017 % on all paths of heredity. After ten generations the population will contain 0.0093 animals of the homozygot recessive genotype “aa”. There will be 0.0055 male and 0.0038 female pigs of the negative genotype. Finally, no negative effect of the usage of hormones for the synchronisation of ovulation in pigs has been proved.