浅谈宫缩素对母猪繁殖及胎儿的影响

缩宫素(催产素)有兴奋子宫平滑肌,引起子宫收缩而促进分娩的作用.当母猪由于体内催产素的含量低,子宫收缩微弱引起难产时,可用催产素催产.催产素的使用是有一定适应症的,不能滥用,也不能超剂量使用,如果使用不当,不仅催产不成,反而会造成胎儿窒息而死,母猪子宫破裂而亡,造成不必要的损失.     

正确使用催产素治疗母猪难产

催产素形成于丘脑下部的室旁核,并且呈滴状沿丘脑下部--垂体后叶径中的轴突运送到垂体后叶贮存.在分娩过程中,由于来自子宫和产道的刺激,可导致催产素的释出.催产素有兴奋子宫平滑肌,引起子宫收缩从而发生分娩作用.当母猪因体内催产素含量较低,子宫收缩微弱而引起难产时,可用催产素催产. 1.催产素对子宫的收缩作用以临产及刚分娩后较为敏感,无分娩预兆时催产无效. 2.由骨盆狭窄、产道受阻、胎位不正等引起的难产或有剖宫产史的母畜禁用,否则可能因子宫剧烈收缩而发生破裂死亡. 3.猪胎盘属于弥散型胎盘,胎儿胎盘和母体胎盘的联系不紧密.子宫的强烈收缩容易使二者引起分离.如果胎儿不能很快产出,就可能缺氧死亡.在临床上常可见到使用催产素治疗难产时产出死胎较多.所以催产素使用剂量要适宜.一般每次20～40IU,根据子宫收缩及胎儿排出情况可以考虑间隔2～3h重复使用1次.     

催产素在母猪生产中的正确使用方法

催产素是一种特殊结构的环状肽类激素,有兴奋子宫平滑肌,引起子宫收缩,从而促进分娩的作用。当母猪由于体内催产素的含量较低、子宫收缩微     

正确使用催产素治疗母猪难产

催产素的作用是在分娩中促进母体对幼体的自然生产,当受到来自体内和体外的刺激时,垂体后叶会将贮存的催产素释放出来,形成分娩活动。催产素在雌性哺乳类生物分娩时对子宫产生刺激,子宫平滑肌兴奋,并引发其收缩进而形成分娩,同时促进乳汁排出。适时使用催产素是治疗母猪难产症的有效方式,如果母猪体内垂体后叶中贮存的催产素含量少,同时子宫收缩的幅度较弱,引发难产情况发生时,可以使用催产素进行催产。在母猪难产时,要适量使用催产素,一般情况每次使用剂量为10~20IU。     

提高受胎率的一些新技术和方法

1　催产素的应用受胎率在很大程度上取决于催产素的应答。授精前按摩子宫颈、子宫体 ,可增加催产素的分泌 ,提高生殖器官生理活性。输精前 5— 7分钟肌注催产素 40单位 ,受胎率可提高 2 0 % ;对子宫没有脓汁和胎儿干尸化的永久性黄体 ,间隔 2小时肌注催产素 1 0 0单位 ,连续 4次 ,可使母牛在注后 1 62± 84小时排卵 ;应用垂体后叶素或麦角新碱 ,还可促进分娩后子宫复旧。2　维生素的应用2 .1　维生素Ｂ1 2 作为冷冻精液解冻液 ,剂量为50 0微克 /毫升 ,在 3 5～ 40℃条件下解冻 ,比对照组提高受胎率 1 2 5%。2 .2　输精当天和输精后 5— 6天…     

使用催产素治疗母牛难产时的注意事项

催产素有兴奋子宫平滑肌 ,引起子宫的收缩从而发生分娩之作用。当母牛由于体内催产素的含量较低 ,子宫收缩微弱引起难产时 ,可用催产素催产 ,其中应注意的事项有 :1　催产素对子宫的收缩作用以临产及刚分娩后更为有效 ,无分娩预兆时用催产素无效。2　催产素主要作用于子宫体 ,对子宫颈的作用微弱。所以 ,子宫颈未张开或助产过迟子宫不再收缩 ,子宫颈已经缩小时 ,用催产素效果不理想。3　骨盆过狭、产道受阻、胎位不正等原因引起的难产以及有剖腹产史的母牛禁用 ,否则子宫剧烈收缩时可能发生破裂 ,所以在使用催产素前须先检查产道 ,胎位情况…     

母猪难产如何正确使用催产素

<正>催产素有兴奋子宫平滑肌,引起子宫的收缩从而发生分娩作用。当母猪由于体内催产素的含量低,子宫收缩微弱引起难产时,可用催产素催产,但如果使用不当,不但发挥不了其应有作用,还可能产生很大的不良反应。通常,当母猪分娩过程较慢时,有的饲养员或初学兽医人员,为求快速分娩,喜欢用"催产素"(缩宫素)来催产。这里着重提出的是催产素的使用是     

催产素在养猪生产中的应用

<正>在母畜分娩过程中,由于来自子宫和产道的刺激,可导致催产素的释出。催产素有兴奋子宫平滑肌,引起子宫的收缩从而发生分娩的作用。当母猪由于体内催产素的含量较低,子宫收缩微弱引起难产时,可用催产素催产。但如果使用不当,不但发挥不了其应有的作用,还可能产生很大的不良反应。     

交巢穴埋线和注射催产素对奶牛产后子宫复旧影响的比较

为了比较奶牛交巢穴埋线与注射催产素对子宫复旧的影响,本试验共选取了20头荷斯坦牛,10头作为试验组1,分娩后在其交巢穴埋线;10头作为试验组2,分娩后在交巢穴注射催产素。观察奶牛的胎衣、恶露排出及子宫复旧情况,发现两种方法对胎衣排出时间的影响差异不显著,而埋线处理对子宫复旧较注射催产素有明显的促进作用,     

慛产素在养猪生产中的应用

在母畜分娩过程中，由于来自子宫和产道的刺激，可导致催产素的释出。催产素有兴奋子宫平滑肌．引起子宫的收缩从而发生分娩的作用。当母猪由于体内催产素的含量较低，子宫收缩微弱引起难产时．可用催产索催产。但如果使用不当．不但发挥不了其应有的作用，还可能产生很大的不良反应。     

Relationship between contractions of the uterus and concentration of PGF2α in uterine venous blood after luteolysis in gilts

The origin and physiological significance of high pulses of prostaglandin F2α (PGF2α) in uterine venous blood that occur 2-3 days after luteolysis are not well understood. We studied the relationship between contractions of the uterus evoked by exogenous oxytocin (OT) and PGF2α concentration in uterine venous blood on day 17 of the porcine oestrous cycle. The infusion of OT into the uterine artery produced an immediate increase in the uterine intraluminal pressure (UIP) (p < 0.001) and a simultaneous elevation in PGF2α concentration in uterine venous blood (p < 0.0001). The infusion of indomethacin (IND) into the uterine artery slightly decreased PGF2α concentration in uterine venous blood, but it did not suppress uterine contraction or the rapid increase in PGF2α concentration in uterine venous blood just after OT infusion (p < 0.0001), which was lower that in gilts not treated with IND. We conclude that the spikes of PGF2α concentration in uterine venous blood occurring after OT infusion on day 17 of the porcine oestrous cycle are mainly caused by the excretion with venous blood from the remodelled uterus and that PGF2α synthesis may contribute to this. These results suggest that the high spikes in PGF2α concentration that occur 2-3 days after luteolysis in pigs, sheep, cows and mares all have a similar origin.     

Influence of hormone supplementation to extended semen on artificial insemination,uterine contractions,establishment of a sperm reservoir,and fertility in swine

This study was performed to quantify the effect of hormone addition to semen using a low-fertility model to evaluate its effectiveness and mode of action. At 24 h after the onset of estrus, all gilts received a single low-dose AI (0.5 x 10(9) sperm/80 mL) with no hormone (control, C), estrogens (E, 11.5 microg), PGF2alpha (PG, 5 mg of Lutalyse), or oxytocin (OT, 4 IU), which were then evaluated for semen backflow (n = 48), oviductal and uterine sperm numbers (n = 28), uterine contractions (n = 12), pregnancy rate (PR, n = 120), and number of fetuses (n = 67). In Exp. 1, backflow of semen from the uterus was collected for 8 h after AI, whereas PR and fetuses were assessed at d 25 to 30 after AI. In Exp. 2, backflow was collected and reproductive tracts flushed to determine sperm numbers in the oviducts and the anterior segments of the uterus. In Exp. 3, sows were monitored for uterine contractions for 1 h before AI and for 2 h after AI. In Exp. 1, there was a treatment x time interaction for fluid loss (P < 0.001), but by 8 h after AI, there was no difference in the total volume (70 +/- 1 mL) of semen lost between hormone treatments (85%) compared to controls (90%). There was also a treatment x time interaction (P < 0.05) for number of sperm lost in the backflow (2.1 +/- 0.1 x 10(8)), but by 8 h following AI, there was no effect on total sperm lost for the hormone treatments (38%) compared to C (54%). There was a trend (P = 0.10) for increased numbers of sperm in the uteri of hormone-treated gilts (6.0 +/- 1.3 x 10(4)) compared with C gilts (2.2 +/- 1.3 x 10(4), but there was no effect of treatment on sperm numbers in the oviducts (3.2 +/- 1.3 x 10(4)). Within 0.5 h of AI, there was an increase in the frequency of contractions for PG compared with the other treatments (14.2 vs. 6.3/h, P < 0.005), however there was no effect on amplitude (54 mmHg) or duration (35 s) of contractions. The PR was not influenced by treatment and averaged 54% (P > 0.60), but total numbers of healthy fetuses were increased (P < 0.04) by PG (8.7) and tended (P = 0.06) to be increased for OT (8.4), but not for E (7.2) compared to C (5.8). Hormone addition to semen increased numbers of fetuses and this may be related to an alteration in the pattern of fluid and sperm loss after AI and a tendency for increased numbers of sperm in the anterior segment of the uterus. Therefore, in situations of lowered fertility, hormone addition could be a strategy to limit infertility in swine.     

Maternal and fetal influences on uterine and conceptus development in the cow: II. Blood flow and nutrient flux

Objectives of this study were to evaluate maternal and fetal influences on uterine and umbilical blood flows and nutrient fluxes of gravid uterine tissues of cows. Brahman cows with Brahman or Charolais fetuses and Charolais cows with Brahman or Charolais fetuses were used. Indwelling catheters were placed into a uterine artery and vein, an umbilical vein, and a fetal femoral artery and vein at 220 +/- .4 d after mating. Uterine and umbilical blood flows (liters/min) and net uptakes of oxygen, glucose, lactate, alpha-amino N, urea N, ammonia N, and estrone sulfate by the gravid uterus, fetus, and uteroplacenta were determined on d 227 +/- .4. Uterine blood flows in Brahman cows with Brahman (5.01) or Charolais (4.66) fetuses were similar but less (P less than .001) than in Charolais cows with Brahman (7.14) or Charolais fetuses (9.24), which differed (P less than .01). Umbilical blood flows of Charolais (3.78) were greater (P less than .01) than those of Brahman (2.29) fetuses. Rate of placental D2O clearance as well as net fetal uptake of oxygen, glucose, and alpha-amino N, gravid uterine uptake of alpha-amino N, and uteroplacental uptake of glucose and release of estrone sulfate were greater with Charolais than with Brahman fetuses. Gravid uterine oxygen uptake and estrone sulfate release and gravid uterine and uteroplacental lactate output were influenced by the interaction between cow and fetal breed. It is suggested that fetal growth may be limited by uterine blood flow and by function of the uteroplacenta, particularly in late gestation.     

Boar Contact does not Induce Oxytocin Release During the Period of Embryo Migration in Sows

Nine multiparous cyclic sows with permanent jugular catheters were introduced to a boar at day 10 (n = 9) or 11 (n = 5) after ovulation to study the effect on oxytocin (OT) release. If it occurs, the release of OT might play a role in embryo migration which occurs around this time, by stimulating uterine contractions. Blood samples were taken before introduction of the boar and at 2-min intervals up to 10 min after boar introduction. On average, OT levels after boar introduction were not higher than before. In only three out of the 14 occasions of boar introduction, a rise in OT level was observed that was higher than two times the standard deviation above base level. However, even on these occasions OT levels were far below the range normally observed during other events where exogenous stimuli cause OT release, such as boar introduction during estrus and suckling during lactation. We conclude that boar contact around day 10 of the estrous cycle does not induce a biologically significant OT release in sows.     

Relationships between uterine length and number of fetuses and prenatal mortality in pigs

Relationships between the length of uterine horn and number of fetuses and prenatal mortality were characterized in 320 pregnant pigs at 3, 5, 7, 9, 11, 13 and 15 wk of gestation in a cross-sectional design. Genital tracts of all pregnant animals available on the days of collection were measured. Length of each uterine horn, numbers of fetuses and corpora lutea (CL) were recorded and prenatal mortality was calculated. With each additional fetus, length of the uterus increased 10 cm regardless of stage of gestation (P less than .001). The association of number of fetuses and uterine length was local and confined to that horn in which the fetus resided and did not extend to the opposite horn. As number of CL increased, number of fetuses also increased as did prenatal mortality. There was a significantly negative correlation between uterine length and prenatal mortality when animals were classified into four groups on the basis of number of CL; less than 10, 10 to 14, 15 to 18 and greater than 18. Results indicated that the number of fetuses and prenatal mortality were closely correlated with length of the uterus. Length of the uterus appeared to be an important limiting factor to litter size as number of CL increased.     

Effect of an oxytocin antagonist on prostaglandin F2 alpha secretion and the course of luteolysis in sows.

The role of oxytocin (OT) in the regulation of prostaglandin F2 alpha (PGF2 alpha) secretion during luteolysis in gilts was studied using a highly specific OT antagonist (CAP-581). In Experiment 1 gilts on Days 14 to 19 of the oestrous cycle in Latin square design were used, to determine the dose and time of application of OT and CAP. In Group I (n = 6) gilts were treated intravenously with saline or with 10, 20 and 30 IU of OT. Concentrations of the main PGF2 alpha metabolite i.e. 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) were measured in blood samples as uterine response to the treatment. Twenty IU of OT was the most effective to stimulate PGFM release and this dose was used after CAP treatment in gilts of Groups II, III and IV. Gilts of Group II (n = 3) were injected into the uterine horns (UH) with saline (5 ml/horn) or CAP (2 mg, 3 mg and 4 mg; half dose/horn) and OT was injected (i.v.) 30 min thereafter. Any of the CAP doses given into the UH affected PGFM plasma concentrations stimulated by OT. In Group III (n = 4) gilts were infused (i.v.) for 30 min with CAP (9 mg, 14 mg and 18 mg/gilt) followed by 20 IU of OT. All doses of CAP effectively inhibited OT-stimulated PGF2 alpha release, therefore 9 mg was selected for the further studies. Gilts of Group IV (n = 4) received OT 4, 6 and 8 h after CAP to define how long CAP blocks the OT receptors. Concentrations of PGFM increased after any of this period of time. Thus, we concluded that 9 mg of CAP infused every 4 h will effectively block OT receptors. In Experiment 2, gilts (n = 4) received CAP as a 30-min infusion every 4 h on Days 12-20 of the oestrous cycle. Control gilts (n = 3) were infused with saline. CAP infusions diminished the height of PGFM peaks (P < 0.05). Frequency of the PGFM (P < 0.057) and OT (P < 0.082) peaks only tended to be lower in the CAP-treated gilts. Peripheral plasma concentrations of progesterone (P4) and oestradiol-17 beta (E2) and the time of luteolysis initiation as measured by the decrease of P4 concentration were the same in CAP- and saline-treated gilts. The macroscopic studies of the ovaries in gilts revealed lack of differences between groups. We conclude that OT is involved in the secretion of luteolytic PGF2 alpha peaks but its role is limited to controlling their height and frequency. Blocking of OT receptors did not prevent luteolysis in sows.     

Relationships between uterine and fetal traits in rabbits selected on uterine capacity

The aim of this study was to investigate whether uterine capacity (UC) in rabbits was related to uterine horn length and weight and whether these uterine traits and vascular supply were related to fetal development and survival. Data from 48 unilaterally ovariectomized (ULO) does of the High and 52 ULO does of the Low UC lines of a divergent selection experiment on UC were used. Does were slaughtered on d 25 of fifth gestation. The High line showed higher ovarian weight (0.08 g, P < 0.05) linked to a higher ovulation rate (1 ovum, P < 0.05) and greater length of the empty uterine horn. There were no differences between lines in the remaining doe traits. The number of implanted embryos and live fetuses, fetal survival, and uterine weight and length were positively associated and explained most of the observed variation. Average weights of the live fetuses and their fetal and maternal placentae were not related to uterine weight and length. The linear regression coefficient of full uterine horn length on the number of live fetuses was 2.43 +/- 0.21. The weight of the full uterine horn showed a small quadratic relationship (P < 0.05) with the number of live fetuses. Full uterine horn length, after adjusting for the number of embryos, was negatively associated (P < 0.001) with the number of dead fetuses. The linear regression coefficient of average fetal placental weight of the live fetuses on number of implanted embryos was higher (P < 0.10) in the Low line (-0.23 +/- 0.04 vs. -0.12 +/- 0.04). The linear regression coefficient of average weight of the live fetuses on the average weight of their fetal placentae was higher (P < 0.10) in the High line (2.56 +/- 0.47 vs. 1.27 +/- 0.57). The High line was more efficient, most likely because an increase in intrauterine crowding has a lesser effect on the development of fetal placentae and fetuses. The fetal position within the uterus did not affect the proportion of dead embryos. Fetuses with placentae receiving a single blood vessel had a higher probability of death (P < 0.001) and the lowest weight. There was no difference between lines for individual weight of the live fetuses, but the High line showed higher individual weights of fetal (P < 0.01) and maternal placentae (P < 0.10). Live fetuses in the midportion of the uterus were lighter in weight (P < 0.05) than in the oviductal and cervical regions (20.3 vs. 21.6 and 21.7g). Increasing uterine capacity increases uterine length and decreases weights of fetus and fetal placenta in rabbits.     

Effect of stage of gestation, litter size and uterine space on the incidence of mummified fetuses in pigs

Factors associated with incidence of mummified fetuses at 7, 9, 11, 13 and 15 wk of gestation were determined in a cross-sectional design involving 209 pregnant pigs. Percentage of observed mummies increased from 2.1 to 12.2% as gestation progressed. Incidence of mummies at 7 wk of gestation was not different between litters of nine fetuses or fewer and those of 10 fetuses or more. During the period of 7 to 15 wk of gestation, the incidence of mummies remained constant at about 1% in litters of nine fetuses or fewer, whereas in litters of 10 fetuses or more the incidence increased linearly from 1 to 12% (P less than .01). In litters of nine fetuses or fewer, a mummy occupied no less space than a live fetus until 13 wk of gestation. In litters of 10 fetuses or more, a mummy occupied less space than did a live fetus after 7 wk of gestation. An increase in the incidence of mummies in larger litters was associated with uterine space per fetus below that needed for development and survival. The 12% fetal loss in late gestation was associated with less uterine space per fetus. Length of uterine horns, litter size and stage of gestation together accounted for 12% of the variation in incidence of mummies (P less than .001). A longer uterus had greater space per fetus, a larger number of live fetuses and a lower incidence of mummies.     

Comparison of the virulence of two isolates of porcine parvovirus in 72-day-old porcine fetuses.

Two strains of porcine parvovirus (PPV), designated Kresse and NADL-8, were compared for relative virulence in porcine fetuses. Strain Kresse was injected into the amniotic fluid of all fetuses of 1 uterine horn of each of 2 pregnant gilts at 72 days of gestation. Strain NADL-8 was administered similarly to fetuses of 4 other gilts at the same stage of gestation. All gilts were killed and necropsied 35 days later. Selected tissues of all fetuses were tested for infectious virus and viral antigen. Sera from live fetuses were tested for antibody to PPV. These tests confirmed that most fetuses exposed to PPV by intra-amniotic injection became infected. All of 11 fetuses exposed to strain Kresse by intra-amniotic injection were alive at the time of necropsy, and all appeared clinically normal. In contrast, 8 of 24 fetuses exposed similarly to strain NADL-8 were dead. Many of the fetuses from the uterine horns contralateral to the uterine horns inoculated with virus were infected after 72 days of gestational age by intrauterine spread of the virus. Four such fetuses, 3 infected with the NADL-8 strain and 1 infected with the Kresse strain, were dead at the time of necropsy. These findings were inconsistent with those of a previous report, which indicated that the Kresse strain of PPV was markedly more virulent than the NADL-8 strain of PPV for porcine fetuses. A possible reason for this apparent discrepancy is discussed.     

Uterine and umbilical blood flows and net nutrient uptake by fetuses and uteroplacental tissues of cows gravid with either single or twin fetuses.

To evaluate the influence of cow breed and number of fetuses on uterine and umbilical blood flows and nutrient fluxes or uterine tissues from gravid cows, surgery was performed on Charolais or Hereford cows with single or twin fetuses at 177 +/- .2 d (mean +/- SEM) after mating. Indwelling catheters were placed in a fetal femoral artery and vein, in an umbilical vein of each fetus, and in a uterine artery and vein of each gravid horn. Deuterium oxide (D2O) was infused into a fetal femoral vein at 183 +/- .3 and 190 +/- .5 d after mating to estimate uterine and umbilical blood flows (liters/minute). Blood oxygen and plasma glucose and lactate concentrations were determined and uterine arterio-venous (A-V) and umbilical venous-fetal arterial (v-a) differences and net uterine and fetal uptakes were calculated. Net utilization by the uteroplacenta was calculated as the difference between uterine and fetal net uptakes. Uterine blood flows were lower (P less than .01) in Hereford (4.80 +/- .28) than in Charolais (7.07 +/- .33) and lower (P less than .01) per fetus in cows with twin fetuses (5.22 +/- .34) than in cows with a single (6.65 +/- .28) fetus. Umbilical blood flows were greater for single than for twin fetuses. Fetal oxygen and glucose net uptakes averaged 57 and 12%, respectively, of net uteroplacental utilization. Lactate was released from uteroplacental tissues to fetal (42%) and maternal circulations (58%). Fetal oxygen uptakes tended to be less for twin fetuses (P = .08) than for a single fetus.(ABSTRACT TRUNCATED AT 250 WORDS)