Stimulation of fetal hypothalamus induces uterine contractions in pregnant rats at term

The fetal brain is thought to have a role in the onset and progression of labor. Evidence also exists for fetal oxytocin release just before and during parturition. The present study examined whether activation of the fetal brain could induce uterine myometrial contractions through oxytocin receptors in the dam. Under urethane anesthesia, electrical stimulation of the hypothalamus of fetal rats that were still connected with the dams by an intact umbilical cord induced uterine contractions in term pregnant rats. Intraperitoneal injections of synthetic oxytocin in fetuses induced uterine contractions in the dams similar to those induced by electrical stimulation of the fetal hypothalamus. Maternal intravenous injections of an oxytocin antagonist immediately attenuated uterine contractions induced by fetal oxytocin injections and electrical stimulation of the fetal hypothalamus. These findings suggest the possibility that oxytocin released from the fetal hypothalamus is involved in parturition.     

The effects of vetrabutin chlorhydrate and oxytocin on stillbirth rate and asphyxia in swine

Oxytocin and vetrabutin chlorhydrate (VC) are used to reduce the duration of farrowing in swine. The objective of the present study was to evaluate the use of these products on intra-partum stillbirth (IPS) rate and asphyxia. At the onset of parturition, sows (n=180) were allocated to receive 2 mL of saline (control group), oxytocin (40 IU i.m.) or 100mg of VC per 60 kg of body weight, with all treatments given i.m. Oytocin-treated sows had a higher number of IPS than the VC and Control groups (means, 1.2, 0.8 and 0.6, respectively; P<0.001), and the highest percentage of ruptured umbilical cords (76.0, 9.4 and 37.5%; P<0.003). There were differences among groups for duration of farrowing (means, 163.0, 211.2 and 306.9 min in the oxytocin, VC and control groups; P<0.001), interval between piglets (13.9, 19.2 and 28.1 min; P<0.001), and in IPS, the incidence of ruptured umbilical cords was 76.0, 9.4 and 37.5% (P<0.003) and absence of a fetal heartbeat was 53.3, 16.9 and 12.5% (P<0.05). Although oxytocin decreased both duration of farrowing and interval between piglets by approximately 50% relative to control sows, it resulted in a significantly higher rate of IPS, in association with a much higher incidence of ruptured umbilical cord and absence of a fetal heartbeat. Treatment with VC reduced farrowing duration by approximately 1.5h, with an IPS rate that was not significantly different from controls but significantly lower than that of oxytocin-treated sows.     

Comparative routes of oxytocin administration in crated farrowing sows and its effects on fetal and postnatal asphyxia

Oxytocin is used to induce and control parturition; nevertheless, an increase in uterine contractions decreases blood flow and gaseous exchange through the uterus predisposing to intra-partum mortality in pigs. The objective of the present study was to evaluate the effect of different oxytocin administration routes on myometrial activity, fetal intrauterine hypoxia and postnatal asphyxia in crated farrowing sows. Yorkshire x Landrace hybrid sows (n = 300), that were approaching the time of parturition, were randomly assigned into six groups. Each group included 50 sows, 10 for each of the parities from one to five. A 40-IU oxytocin dosage was administered by intramuscular (IM), or intravulvar (IVU) routes, or 20 IU was administered via intravenous (IV) route. Groups 1 (G1), 3 (G3) and 5 (G5) were administered 0.9% saline solution (NaCl) IM, IVU and IV, respectively, whereas groups 2 (G2), 4 (G4) and 6 (G6) were treated with oxytocin IM, IVU and IV, respectively. There was a significantly (P < 0.05) greater number of intra-partum stillbirths (IPS) for the oxytocin treatments, as compared with the control groups, especially with the IVU and IV routes; a lesser number of IPS and lesser IPS with broken umbilical cords was observed with the IM administration route. Oxytocin and control IV administration resulted in longer farrowing durations. Administration of IV-oxytocin resulted in a greater number (P < 0.05) of intrauterine distressed neonates compared with its corresponding control and interpreted through dips II, a fetal cardiac frequency deceleration which determines acute fetal suffering. Independent of the route of oxytocin administration, the treatments resulted in twice as many dips II compared with the respective control groups. The use of the cardiotocograph proved to be an excellent tool for establishing the oxytocin response dose in farrowing sows. A greater number of piglets born alive, which had undergone bradycardia, also showed severe acidosis and greater meconium staining in oxytocin-treated sows, indicating that the administration time (at birth of the first piglet) as well as the dosage used were not adequate treatment regimens in the present study. Further studies will be conducted to evaluate different dosages and oxytocin administration timing to determine the most desirable treatment regimen to increase myometrial contractibility without compromising fetal welfare and neonatal survival.     

Induction of parturition in swine with prostaglandin analogs and oxytocin

Two trials were conducted to increase the effectiveness of parturition induction with PG analogs. In trial 1, 39 sows were treated with the analog Luprostiol (Pronilen, Vemie /Kempen). Of these, 19 received an additional injection of 30 i.u. oxytocin 24 h later. In trial 2, 126 sows were divided into four groups, three of which were treated with the analog Alfaprostol (Vetem /Milano), while one served as control. Two of the PG-treated groups received an additional oxytocin injection either 24 or 20 h later, respectively. The response to either of the PG analogs resembled that observed during earlier studies although the percentage of sows responding was somewhat lower (70% and 77%, respectively). Oxytocin increased the number of respondents to 84 and 89%, respectively, and parturition commenced promptly. In trial 1, parturition started within 2.1 +/- 1.6 (0 to 5) h after oxytocin, in trial 2 within 1.57 +/- 1.06 (0.5 to 3) h when the interval between prostaglandin and oxytocin was 24 h, and 1.81 +/- 0.84 (0.5 to 3) h when it was 20 h (x +/- SD ). Parturition and viability, birth weight and weaning weight of piglets were normal. The proportion of sows in trial 2 that showed increased body temperature during the first 3 days post partum was reduced from 22.9% in the control group to 8.6, 14.3 and 7.1% in the three groups receiving just PG or PG and oxytocin after 24 or 20 h, respectively.     

Induction of parturition in swine with a prostaglandin analog and oxytoxin: A trial involving dose of oxytocin and parity

The purpose of this experiment was to compare a range of oxytocin doses in order to find the most suitable dose to improve predictability and precision of timing of PGF-induced parturition in sows. Sows randomly allotted to 6 groups - group size varying between 28 and 39 - were either untreated controls (group 1) or received an IM injection of 2 mg of the PGF-analog Alfaprostol (Vetem) on day 111 of pregnancy (day 0 = last day of standing heat), followed 20 h later by 0, 5, 10, 20 or 30 IU oxytocin, respectively (groups 2 - 6). Both length and variability of the time from injection of oxytocin to the onset of parturition decreased with increasing dose. The response was faster and more predictable with older sows than with first litter gilts. A disadvantage of higher doses of oxytocin was the necessity of manual aid (11 % in controls, 52 % with the maximum level of 30 IU oxytocin). Litter size, weight and percentage of piglets weaned and time from weaning to subsequent estrus were not affected by any of the treatments. An oxytocin dose of 20 IU applied 20 h after PGF appeared to give the most effective response, although this will occasionally necessitate manual assistance with parturition.     

The effect of experimental induced hypocalcaemia on uterine activity in the sow during parturition and post-partum

Uterine activity was measured by monitoring intrauterine pressure changes using ballon-tipped catheters placed in the lumen. An infusion rate of Na(2)EDTA of 35 mg/Kg/h gave a chelation rate equivalent to the rate of calcium mobilisation, and when infused at a level greater than this, resulted in a reduction in plasma calcium concentrations and a concomitant reduction in uterine activity. In three of the four sows infused intrapartum, there was complete cessation of uterine activity; however, plasma calcium concentrations of less than 6 mg 100 ml resulted in a reduction in uterine activity at this stage of parturition. The uterus of the sow post-partum appeared to be more sensitive to the effects of hypocalcaemia with reduced uterine activity when plasma calcium concentrations fell below 8.2 mg 100 ml and complete cessation of activity between 6 and 7 mg 100 ml . Although there was evidence of a delay in the expulsion of piglets in the hypocalcaemic sows, there was no evidence of an increased number of stillborn piglets compared with the two control sows.     

Maturation of spontaneous and agonist-induced uterine contractions in the peripartum mouse uterus.

This study tested the hypothesis that the uterus achieves maximum contractile capabilities before the onset of labor. Basal and agonist-stimulated contractions were assessed in uterine strips on Day 15 or 18 of pregnancy, the day of parturition, or 1 day postpartum (n = 4-13 per group). Spontaneous contractions were evident in all groups (n = 4-13 per gestational group); contraction frequency was greater in peripartum groups than in virgin controls ( approximately 4.6 versus 2.8/200 sec). Peak amplitude was nearly 9-fold higher on Days 15 and 18 and over 30-fold higher in the postpartum and 1 day postpartum groups than in nonpregnant mice. Maximum frequency and peak amplitude were achieved in response to 10(-6) to 10(-8) M oxytocin or arginine vasopressin (OT(max) or AVP(max)). Frequency of contractions in response to OT(max) peaked on Day 18 and then declined. Contraction amplitude increased 5-fold on Day 15, declined on the day of birth (equivalent to nonpregnant level), then rebounded to peak on postpartum Day 1. AVP(max) similarly increased frequency and amplitude of contractions, except that maximum contraction amplitude occurred postpartum. Thus, an endogenous oscillator, residing in the uterus, sustains high basal and agonist-induced contraction frequency during pregnancy. Although acceleration of this pacemaker occurred before term, the data suggest that peripartum increases in contraction amplitude characterize the transition to the powerful synchronous contractions of parturition.     

Oxytocin and V1 vasopressin receptors in rabbit endometrium during pregnancy

Neurohypophysial hormone receptors were identified and characterized in rabbit endometrium and decidua by radioligand binding methods. The results strongly support the presence of a heterogeneity of sites in the decidua of parturient rabbits. The oxytocin site (R1) binds oxytocin and oxytocin analogues ([Thr4, Gly7]oxytocin and OTA) with high affinity, whereas the AVP site (R2) was selective for the V1 AVP analogues, [Phe2, Orn8]VT and d(CH2)5TyrMeAVP. The concentration of oxytocin receptors was low (50-100 fmol/mg protein) at oestrus (Day 0) and on Day 29 of pregnancy, but increased significantly (about 8-fold, P less than 0.05) during parturition. Conversely, V1 AVP receptors were more concentrated than the oxytocin sites at the end of pregnancy (150 fmol/mg protein) but did not change during parturition. These results indicate that neurohypophysial hormones have specific receptors not only in the myometrium but also in the uterine mucosa and we suggest that these receptors may participate in the regulation of uterine activity during pregnancy.     

Uterine and fetal asphyxia monitoring in parturient sows treated with oxytocin

Oxytocin is used to induce and control parturition, nevertheless, the increase of uterine contractions decreases blood flow and gaseous exchange through the womb predisposing to intra-partum mortality. The objective of the present study was to evaluate the effect of oxytocin on myometrial activity, fetal intrauterine hypoxia and postnatal asphyxia in sows during farrowing. Hybrid (n = 120) sows approaching the time of farrowing were randomly assigned in two groups of 60 animals each. Group I (G(1): control) was treated IM with saline solution and Group II (G(2)) was injected IM with oxytocin (1IU/6kg LW) as a single dose at birth of the first piglet. Both average number of myometrial contractions and intensity in G(2) were greater (P < 0.01) as compared with G(1). The mean of intra-partum stillbirths (IPS's) and those where fetal cardiac frequency (FCF) or heart beats, could not be detected after birth, were greater (P < 0.01) in G(2) as compared with G(1). The average decelerations of FCF known as dips II, which indicate severe hypoxia, was greater in G(2) (P < 0.01) as compared with that of G(1). There was a greater (P < 0.01) number of intra-partum stillbirths, stained with severe meconium in G(2) when compared with G(1). Oxytocin treatment increased (P < 0.01) the number of pigs born alive with ruptured umbilical cords and those with different grades of meconium staining on their skin. It was concluded that administration of oxytocin at the onset of parturition increased the myometrial activity, decreased fetal cardiac frequency, predisposed the rupture of umbilical cords and the degree of meconium staining, and increased intra-partum mortality.     

Prolongation of gestation in the rat and hamster by naproxen

Administration of naproxen by once or twice daily subcutaneous injection, or orally in the drinking water, was found not to routinely prevent parturition in either the rat or the hamster. However, the duration of labor was prolonged and associated with poor pup viability. The prolonged labor and fetal mortality were thought to be due to suppression of myometrial activity after onset of labor and caused by the episodic administration regimens. Thus fetal deaths could result from asphyxia due to suppression of uterine contractions, after partial or total placental separation had occurred. Naproxen was, therefore, administered on a more continuous basis by subcutaneous implantation of pellets in rat and hamster, or orally every four hours in the rat. Either of these regimens was then able to postpone parturition beyond the range of deliveries in control animals. In such naproxen treated rats there was no sign of placental detachment, even out to day 25 of pregnancy. Fetal viability was preserved and fetuses continued to gain weight. These observations are consistent with a true prolongation of gestation by naproxen rather than merely an interference with the process of labor.     

Fetal and maternal endocrine changes associated with parturition in the goat

In 4 goats maternal jugular plasma concentrations of progesterone started to decline before labor commenced, but levels remained elevated above basal concentrations throughout parturition. Fetal and maternal plasma concentrations of estrogen rose before and during labor, increasing markedly just prior to fetal delivery. Fetal carotid plasma glucocorticoid concentrations appeared to rise over the 5 days prior to parturition, but a significant increase was only noted during labor. Maternal plasma concentrations of glucocorticoids were significantly lower than fetal plasma concentrations of glucocorticoids. Estradiol-17α was the predominant estrogen in both fetal and maternal plasma, less estrone was detected and apparently little estradiol-17β was present.No good correlation was found between plasma progesterone or estrogen and parturient uterine activity; the latter lasted from 22 to 78 hours, with the most dramatic increase occurring close to delivery. It is probable that other agents are involved in controlling uterine activity during parturition in the goat.     

Dietary fibre for gestating sows: effects on parturition progress, behaviour, litter and sow performance

In pig production, parturition progress is a key event for sow's reproductive performance, evaluated by piglet survival and piglets' performance. The aim of this study was to investigate the impact of feeding a high-fibre (HF) diet during gestation on parturition progress and reproductive performance of sows. Forty-two primiparous sows (Large-White × Landrace crossbred) were fed during gestation either a control diet (C diet; 2.40 kg/day, 3.2% crude fibre, in % of dry matter (DM)), or a HF diet (2.80 kg/day, 12.4% crude fibre, in % of DM). All sows received 33 MJ digestible energy per day. Continuous video recordings were done on the parturition day to determine postural changes (standing, sitting, lying) and behavioural activities (nesting behaviour, uterine contractions, restlessness, social behaviour towards piglets) during parturition. Duration of parturition and individual birth intervals were also measured. Piglets' growth was evaluated by weekly weighing from birth until weaning, at 26.5 days of age. Sows were weighed and backfat thickness was measured at mating, on day 105 of gestation, on the 1st day post partum, and at weaning. Durations of parturition and of birth intervals were not affected by the gestation diet and averaged 211 ± 12 min and 16.5 ± 0.9 min (mean ± s.e.), respectively. During the parturition progress, the gestation diet did not affect the frequency and the time devoted to postural and behavioural activities. Dietary treatment during gestation did not influence duration of gestation and weaning-to-oestrus interval, as well as litter size, and number of stillborn and weaned piglets. Piglet weight at birth did not differ between gestation dietary treatments but piglets nursed by HF sows showed a 13.5% greater growth rate during the 1st week of life (P < 0.01) and tended to be heavier at weaning (P = 0.06) compared with C piglets. The HF sows were leaner at the end of gestation (P < 0.05), but variations of sows' weight during gestation and lactation were not affected by the gestation diet. All sows lost the same amount of backfat thickness during lactation. During lactation, the average daily feed intake was not significantly affected by the gestation diet. This study shows that substituting a control diet for a HF diet during gestation has limited effects on farrowing progress and reproductive performance, but improved piglets' growth rate during the 1st week of life and tended to increase their live weight at weaning.     

Effects of inactivation of oxytocin receptor and inhibition of prostaglandin synthesis on uterine oxytocin receptor and gap junction formation and labor in the rat.

Normal term labor is associated with a surge in myometrial oxytocin receptor formation and gap junction development. We have previously shown that inhibition of prostaglandin synthesis by naproxen sodium, 2.0 mg/day, suppressed oxytocin receptor formation but not gap junction formation and prolonged gestation. In this study, we investigated the effects of a specific oxytocin antagonist on oxytocin receptor formation, gap junction formation, and labor in the rat. [Pen1,Phe(Me)2,Thr4,Orn8]oxytocin, a specific oxytocin antagonist, was infused subcutaneously during the last 3 days of pregnancy at 300 micrograms/day. Measurements of myometrial oxytocin receptor concentrations and gap junction formation on days 21 and 22 and days 22-23 (in labor) pregnant uteri showed no significant differences in the Bmax and Kd values between the control and the treated group. Gestation period was not prolonged by the oxytocin antagonist. However, in a separate group of day 23 pregnant rats, the uterine contractile response to 60 mU of oxytocin i.v. was found completely blocked by 10 micrograms of the oxytocin antagonist. These findings suggest that although functional oxytocin receptors did not appear to be essential for the initiation of labor, oxytocin antagonists may still be effective in the prevention of premature contractions. We also examined the effects of a higher dose of naproxen sodium, 5.0 mg/day, on gap junction formation. At this dose, naproxen sodium suppressed both oxytocin receptor and gap junction formation, prolonged gestation, and delayed parturition by 24 h or longer. Prostaglandin appears to be an important regulator or mediator of oxytocin receptor and gap junction formation and plays a critical role in the initiation of labor.     

The ACTH content of plasma in fetal and newborn swine]

ACTH concentration has been estimated radioimmunologically in fetal plasma (100th day of gestation) and in plasma of newborn piglets during the first 24 hours of life and in sows. In comparison to the values of ACTH in sows at the 100th day of gestation during anaesthesia (175 pg/ml) and sows at parturition (235 +/- 77 pg/ml) the concentration in fetal (558 +/- 163 pg/ml) and newborn piglets (448 +/- 158 pg/ml) was much higher. On an average ACTH concentration increased during the first 24 hours of life up to 998 +/- 628 pg/ml. The results are compared to those in other species.     

Induction of parturition in swine with prostaglandin F(2)alpha, estradiol benzoate and oxytocin

Pregnant sows and gilts were administered either 0, 2.5, 5, 10 or 20 mg prostaglandin F(2)alpha (PGF(2)alpha) intramuscularly on Day 112 or 113 of gestation at 0800 h in an effort to induce parturition. The average interval from PGF(2)alpha injection to farrowing was 55.1 +/- 5.7, 29.4 +/- 3.1, 32.1 +/- 4.6, 27.8 +/- 1.8 and 26.9 +/- 1.1 h for 0, 2.5, 5, 10 and 20 mg, respectively. All PGF(2)alpha treatments increased (P < 0.01) over controls the number of sows farrowing 23 to 33 h after injection. The average gestation length was significantly shorter in treated gilts; however, no detrimental effect on pig performance or pig survivability was observed. A second trial evaluated the effect of a 10-mg dose of PGF(2)alpha on the induction of parturition in sows in order to obtain a majority of sows farrowing within normal working hours (0700 to 1700 h). The interval from injection to farrowing was decreased (P < 0.05) by PGF(2)alpha treatment (66.2 +/- 5.3 vs 28.1 +/- 2.2 h). Fifty-seven percent (P < 0.05) of PGF(2)alpha-treated sows farrowed between 0700 and 1700 h as compared to 13.6% for control sows. A third trial was conducted to examine a sequential treatment of PGF(2)alpha and oxytocin to control the time of parturition more precisely. Sows receiving only 10 mg of PGF(2)alpha farrowed on an average 31.1 +/- 1.4 h after injection. The injection of 40 IU oxytocin 24 to 28 h after PGF(2)alpha decreased (P < 0.05) the interval from PGF(2)alpha to farrowing (28.1 +/- 0.9 h). The addition of oxytocin increased (P < 0.05) the number of sows farrowing within 3 h of injection (33 vs 86% for PGF(2)alpha and PGF(2)alpha + oxytocin treatments, respectively). A fourth trial was designed to determine if the addition of exogenous estradiol benzoate (EB) to a sequential treatment of PGF(2)alpha and oxytocin would improve the predictability and synchronization of the induced parturition. Sows were assigned to receive either saline, 10 mg PGF(2)alpha + 40 IU oxytocin or 10 mg PGF(2)alpha + 5 mg EB + 40 IU oxytocin. The addition of EB reduced (P < 0.01) the variance in the interval from oxytocin to farrowing and added precision to the predicted time of induced parturition.     

Aberrations in uterine contractile patterns in mares with delayed uterine clearance after administration of detomidine and oxytocin

An experiment was conducted to determine whether the uterotonic effects of oxytocin, a drug used to treat mares that have a delay in uterine clearance were affected by the sedative detomidine (an alpha2-agonist), a drug used to treat fractious mares. An additional objective was to identify propagation patterns of uterine contractions and determine whether these patterns differed between normal mares and mares with delayed uterine clearance (DUC). Intrauterine pressure was measured in five reproductively normal mares and four mares with DUC during estrus using an 8-F Milar catheter with two discrete pressure sensors. Mares received one of three treatments in random order: detomidine (0.001 mg/kg; i.v.); detomidine followed in 10 min by oxytocin (10 IU; i.v.); and saline (0.9% NaCl 0.5 ml; i.v.) followed in 10 min by oxytocin. All treatments induced waves of contractions; however, only three mares with DUC exhibited contractions after administration of detomidine. Normal mares experienced more uterine contractions (P < 0.01) that tended to last longer (P < 0.06), and were of greater intensity (P < 0.04) than mares with delayed clearance. Administration of detomidine before oxytocin increased the number of contractions (P < 0.02) and increased the maximum intrauterine pressure in the uterine horn (P < 0.05) in normal mares as compared to response after administration of saline and oxytocin. Detomidine had no effect in mares with delayed clearance. All mares had more propagating than non-propagating uterine contractions (74 +/- 8 versus 25 +/- 8%, respectively). Normal mares exhibited a normal propagation pattern more frequently (P < 0.0001) than mares with DUC. Simultaneous (P < 0.05) and inverted (P < 0.03) contractions occurred more frequently in mares with DUC. Administration of detomidine increased the number (P < 0.01), and tended to increase the percentage (P < 0.07) of normal propagating uterine contractions in normal mares, but did not affect propagation patterns in mares with DUC. In conclusion, detomidine augmented the uterotonic effect of oxytocin in normal mares but not in mares with DUC. Data suggest that mares with DUC have a defect in myoelectrical signaling and a decrease in the contractile strength of the uterine muscle.     

县乡两级医院自控硬膜外分娩镇痛对产程及分娩结局的影响

目的观察县乡两级医院产妇行自控硬膜外分娩镇痛对产程及分娩结局的影响,评价县乡两级医院产妇行自控硬膜外分娩镇痛的安全性与可行性。方法选择足月单胎头位妊娠并经阴道试产的初产妇200例,均无硬膜外镇痛禁忌证,根据分娩镇痛要求,将其纳入镇痛组(P组,100例)及对照组(C组,100例)。记录两组第一、二产程及总产程时间,分娩方式,产后出血及催产素使用率,新生儿娩出后1、5min Apgar评分,分娩镇痛的不良反应等。结果 P组较C组的第二产程和总产程显著延长,催产素使用率P组明显高于C组;两组第一产程中转剖宫产率,器械助产率,羊水胎粪污染率,新生儿娩出后1、5min Apgar评分,分娩镇痛的不良反应均无统计学差异。结论硬膜外分娩镇痛可使第二产程及总产程延长、催产素使用率增加,但不增加急诊剖宫产率和经阴道器械助产率,明显降低了社会因素手术率,对分娩结局无不良影响,用于县乡两级医院产妇是安全可行的。     

The use of oxytocin in liquid semen doses to reduce seasonal fluctuations in the reproductive performance of sows and improve litter parameters—a 2-year study

The objective of the present research was to eliminate seasonal fluctuations in year-round reproductive performance of sows and to improve litter parameters by administration of oxytocin into liquid semen insemination doses. A 2-year experiment was performed on crossbreed sows, Polish Large White × Polish Landrace, which were partitioned into two groups: control, insemination without any modification with 100 mL semen doses and oxytocin, insemination with 100 mL semen doses to which 5 IU of oxytocin was added just before insemination. A total of 10,486 inseminations were made. The farrowing rate and obtained litter parameters, including the effect of season, were analyzed. For each litter, the following factors were defined: average litter size, percentage of fetal death and mummified piglets, average piglet birth weight, percentage of piglet mortality, fecundity index, average number of piglets weaned, weaned piglet weight, and daily gain. Sows presented a positive reaction to the experimental factor. A statistically higher farrowing rate for oxytocin group in summer and autumn seasons was confirmed (P ≤ 0.01). Regardless of the season, a higher average litter size was observed in the oxytocin group with the most evident differences for winter, spring (P ≤ 0.01), and summer (P ≤ 0.05). The effect of oxytocin on the percentage of fetal death and mummified piglets born was not confirmed statistically except for winter. Analyzing the fecundity index, higher values were obtained for the oxytocin group in all seasons (P ≤ 0.01), including the lowest difference between groups for winter (51.43) and the highest for summer (100.61). A higher average birth piglet weight and weaned piglet weight were recorded for the oxytocin group in all seasons. The highest differences in birth piglet weight between groups were noted for spring (0.22 kg; P ≤ 0.01) and winter (0.17 kg; P ≤ 0.05) and in weaned piglet weight for winter and spring (0.58 kg and 0.52 kg; for both, P ≤ 0.01). The greatest daily gains were observed in the winter season (P ≤ 0.05) in favor of oxytocin. On the basis of the presented results, it should be noted that the use of oxytocin into insemination doses improves the farrowing rate and other parameters of the reproductive performance of sows. In the absence of negative effects, year-round insemination with oxytocin addition into seminal doses is recommended, which effectively improves the production performance and reduces the problem of seasonality in reproduction.     

Association of Fusarium mycotoxicosis with failure in applying an induction of parturition program with PGF2alpha and oxytocin in sows

This trial was conducted in a farrow-to-finish pig unit from November 1999 to February 2000. Since November 1998 an induction-of-parturition program was applied in gilts and sows with PGF2alpha (2 mL Dinolytic, i.m.) 113 d post service, followed by oxytocin (1 mL Intertocine-S, i.m.) 24 h later. This program resulted in a high proportion of animals farrowing within the working hours of the day. At mid December 1999 splay-legs and edematous swelling and reddening of the vulva started to be observed in newborn piglets. A concurrent decline of parameters related to parturition also was noticed. Mycotoxicological analyses of the feeds revealed a co-occurring contamination with deoxynivalenol and zearalenone. For a 4-week period, sows were divided into two groups: (a) an induction-of-parturition and (b) a non-induction-of-parturition group. Significant differences were found between the two groups relating to prevalence of dystocia (<.05) and pregnancy duration (<.05). Moreover, it was found that prevalence of splay-legs and swelling of the vulva were highly correlated (<.05) with reduction of percentage of sows farrowing within the working day and increase of pre-weaning mortality. It was concluded that such an induction-of-parturition program should be avoided during a Fusarium mycotoxicosis.