Induced parturition in pigs with Alfaprostol

The potential of Alfaprostol (ALF) to induce parturition in pigs was evaluated in field trials at two locations. Sows of varying parity and breeding were randomly assigned to receive 0, 0.5, 1, 2 or 3 mg ALF per head. Intramuscular injections were given 2 d prior to expected parturition date. Sows receiving ALF, regardless of dose, farrowed in significantly less time than controls. The average time (h) from injection to first birth by location (1 or 2) and ALF dose (0, 0.5, 1, 2, 3) respectively was as follows: Location 1, 76.2±5.7, 35.4±5.3, 34.7±6.6, 43.7±7.2, 34.9±8.6; Location 2, 69±3.9, 38.4±38, 32.7±3.8, 30.2±3.7, 31.3±3.9. Comparison of sow productivity (i.e., farrowing to farrowing interval, number of pigs born and weaned, among doses made prior to, during, or following ALF treatment) revealed no differences (P>0.05). The variability among and within doses associated with time of first birth was similar to results of earlier investigations with other prostaglandins used to induce birth in swine. It was concluded that ALF was effective for inducing parturition, and since 0.5 mg ALF was as effective as all other doses (P>0.05), it was the minimum effective dose in this study.     

Oxytocin-induced parturition in copper-deficient guinea pigs.

Dietary copper-deficient guinea pig dams (0.8 microgram Cu/g diet) were administered oxytocin to induce delivery of pups, whereas dietary copper-sufficient guinea pig dams (5.8 micrograms Cu/g diet) had uneventful deliveries with 79% surviving pups. The copper-deficient dams carried the fully-formed fetuses to term but did not go into labor unless 0.5 to 6.2 U oxytocin was administered (i.m.). Birth of live pups from copper-deficient dams increased from 28% overall, to 50% if oxytocin was administered in a timely manner. Many pups died of internal hemorrhages probably the result of defective connective tissue crosslinks requiring copper as a co-factor for lysyl oxidase activity. Dietary copper deficiency may be a factor in depressed parturition in the copper-deficient guinea pig dam that responds to administration of exogenous oxytocin for delivery of pups.     

Influence of in vitro systems on embryo survival and fetal development in cattle

In vitro systems are commonly used for the production of bovine embryos. Comparisons between in vivo and in vitro produced embryos illustrate that the morphology of preimplantation-stage embryos differ significantly, the survival of embryos and fetuses is decreased, the size distributions of the populations of conceptuses and fetuses are altered throughout gestation, and placental development is significantly changed. Taken together these findings indicate that exposure to some in vitro environments during the first 7 days of life can profoundly influence fetal and placental development in cattle. An understanding of how in vitro oocyte maturation, in vitro fertilization, and embryo culture systems influence both fetal and placental development should result in systems that consistently produce normal embryos, fetuses, and calves.     

Influence of delayed metamorphosis on postsettlement survival and growth in the sipunculan Apionsoma misakianum

Abstract. Certain stresses experienced by marine larvae from many groups can dramatically reduce aspects of juvenile performance. This study reports the effects of delayed metamorphosis and nutritional stress on survival and growth of the deposit-feeding sipunculan Apionsoma (= Golfingia ) misakianum . Approximately 600 larvae collected from the Florida Current plankton were distributed among 3 treatment groups. Ninety larvae (controls) were offered sediment and adult-conditioned seawater 4 d after collection, to induce metamorphosis; larvae of this species could not be induced to metamorphose by increasing the K⁺ concentration of seawater. The remaining 500 larvae were kept swimming for either 2 or 4 weeks, with or without phyto-plankton (clone T-ISO). At the end of the periods of prolonged larval swimming, subsampled larvae (360) were induced to metamorphose as in the controls. Surviving individuals were retrieved 6 weeks after the addition of excess sediment in all treatments, and weighed to document growth. Neither delayed metamorphosis nor starvation influenced juvenile survival. However, starving larvae for 2 weeks significantly reduced mean juvenile growth rates relative to the mean growth rate of control individuals (p<0.0001), while prolonging larval life by 4 weeks significantly reduced mean juvenile growth rates (p<0.05) whether or not larvae were fed. Reduced juvenile growth rates may have been caused by nutritional stress experienced by larvae in both the starved and fed treatments. The rapid response of freshly collected larvae to sediment indicates that competent larvae of this species routinely delay metamorphosis in the field. The extent to which they also experience food limitation is not yet clear. If competent larvae are food limited while delaying metamorphosis in the field, our results suggest that juveniles will grow more slowly and may thus exhibit reduced fitness.     

Staphylococcal infection in guinea pigs with enhanced delayed hypersensitivity induced by Staphylococcus aureus surface antigens

A comparative study was made of the relationship between the DHS phenomenon and certain staphylococcal antigens and the intensity of infectious process in sublethal infection of guinea-pigs by Staphylococcus aureus. The protective effect, which was manifested by reduced amounts of staphylococcal colonies in spleen tissues and elevated level of lymphocytes, and neutrophil activation, correlated with DHS induced by surface antigens under study (cell wall, peptidoglycan, protein A). Incomplete combination or certain antigens induced DHS but did not increase the resistance to the following infection.     

Gastrin in fetal and neonatal pigs

1. The concentration and molecular profile of gastrin were examined in plasma and tissue extracts of fetal and neonatal pigs from 93 days gestation up to 12 weeks of age and also in the fetal gastric contents. 2. Gastrin was present in the gastrointestinal tract and plasma of fetal pigs at 93 days gestation. The concentration in both plasma and antral extracts increased progressively up to birth and continued to rise postnatally, reaching a peak at about 3 weeks of age in plasma and 6 weeks in the antrum. 3. In blood the major molecular form of gastrin was G34 (up to 80%), while in the antrum the major form was G17 (66-91%). The percentage of G34 in the antrum was highest in later gestation (21%), and reached adult proportion by 8 weeks of age (4%). 4. A considerable amount of gastrin, chiefly G17, was detected in the fetal gastric contents. Synthetic human G17 was stable in fetal gastric contents when incubated at 37 degrees C for 60 min, although, when incubated with gastric contents from a sow, it disappeared within 5 min. 5. It is suggested that the presence of gastrin in fetal gastric contents may be important in stimulation of fetal gut development.     

Neonatal piglet survival: impact of sow nutrition around parturition on fetal glycogen deposition and production and composition of colostrum and transient milk

Piglet survival is a major problem, especially during the first 3 days after birth. Piglets are born deficient of energy, but at the same time they have a very high energy requirement because of high physical activity, high need for thermoregulation (because of their lean body with low insulation) and high heat production in muscle tissues. To be able to survive, newborn piglets may rely upon three different sources of energy, namely, glycogen, colostrum and transient milk, which orchestrate to cover their energy requirements. Piglets are born with limited amounts of energy in glycogen depots in the liver and muscle tissues and these depots are sufficient for normal activity for ∼16 h. Intake and oxidation of fat and lactose from colostrum must supply sufficient amount of energy to cover at least another 18 h until transient milk becomes available in the sow udder ∼34 h after the first piglet is born. Selection for large litters during the last two decades has challenged piglets even further during the critical neonatal phase because the selection programs indirectly decreased birth weight of piglets and because increased litter size has increased the competition between littermates. Different attempts have been made to increase the short-term survival of piglets, that is, survival until day 3 of lactation, by focusing on improving transfer of vital maternal energy to the offspring, either in utero or via mammary secretions. Thus, the present review addresses how sow nutrition in late gestation may favor survival of newborn piglets by increasing glycogen depots, improving colostrum yield or colostrum composition, or by increasing production of transient milk.     

Induction of parturition in pigs by intravaginal application of the prostaglandin analog cloprostenol

Cloprostenol was deposited in the vaginal lumen of sows on Day 111 of pregnancy at dosages of 100, 125 or 175 g and volumes of 1, 2 or 5 ml, respectively. A control group was treated with physiological saline. In 92 out of 93 prostaglandin-treated sows, parturition commenced approximately 22 h after application, with no significant differences between dose levels or volumes. There were also no differences in the average size and weight of litters born, weaning weight, frequency of postpartum complications or post-weaning fertility. Intravaginal application of cloprostenol is thus a simple and efficient means of inducing parturition in sows.     

Dexamethasone and estradiol benzoate induced parturition in dairy cattle

Fifteen 2-year-old Holstein cows and 21 mature Holstein cows were assigned to one of three groups. Cows in Group I calved spontaneously. Cows in Groups II and III received single intramuscular injections of 20 mg dexamethasone and 25 mg estradiol benzoate to induce parturition prematurely. In addition, cows in Group III received a single intramuscular injection of 12.5 mg estradiol benzoate 48 hr prior to dexamethasone and estradiol benzoate. The objective of the experiment was to determine the effectiveness of estradiol benzoate in combination with dexamethasone on traits at parturition and on productive and reproductive characteristics following parturition. Induction of parturition shortened gestation length and increased the incidence of retained placentas (both P < .01). All induced cows calved between 21 and 59 hr postinjection with less (P < .05) udder edema when compared to control cows. Mean plasma estrogen concentrations, using an assay system which does not measure estradiol benzoate, were not different among groups following injections of estradiol benzoate. Mean estradiol-17β concentrations in induced cows, however, using an assay system which does recognize estradiol benzoate (70.8% crossreactivity), were higher (P < .01) following estradiol benzoate injection, tended to be higher through parturition, and remained elevated (P < .01) at 12 and 24 hr following parturition when compared to cows calving spontaneously. Mean monthly milk production and the 2x, 305-ME records for milk, fat and FCM were not different among groups.     

Gastrointestinal dysfunction induced by early weaning is attenuated by delayed weaning and mast cell blockade in pigs

Our previous work has demonstrated that weaning at 19 days of age has deleterious effects on mucosal barrier function in piglet intestine that are mediated through peripheral CRF receptor signaling pathways. The objectives of the present study were to assess the impact of piglet age on weaning-associated intestinal dysfunction and to determine the role that mast cells play in weaning-induced breakdown of mucosal barrier function. Nursing Yorkshire-cross piglets were either weaned at 19 days of age (early-weaned, n = 8) or 28 days of age (late-weaned, n = 8) and housed in nursery pens. Twenty-four hours postweaning, segments of midjejunum and ascending colon from piglets within each weaning age group were harvested and mounted on Ussing chambers for measurements of transepithelial electrical resistance and serosal-to-mucosal [(3)H]mannitol fluxes. Early weaning resulted in reductions in transepithelial electrical resistance and increases in mucosal permeability to [(3)H]mannitol in the jejunum and colon (P < 0.01). In contrast, postweaning reductions in intestinal barrier function were not observed in piglets weaned at 28 days of age. Early-weaned piglet intestinal mucosa had increased expression of CRF receptor 1 protein, increased mucosal mast cell tryptase levels, and evidence of enhanced mast cell degranulation compared with late-weaned intestinal mucosa. Pretreatment of piglets with the mast cell stabilizer drug cromolyn, injected intraperitoneally 30 min prior to weaning, abolished the early-weaning-induced intestinal barrier disturbances. Our results indicate that early-weaning stress induces mucosal dysfunction mediated by intestinal mast cell activation and can be prevented by delaying weaning.     

Cortisol in fetal fluids and the fetal adrenal at parturition in the tammar wallaby (Macropus eugenii)

Glucocorticoid hormones may play a critical role in initiating parturition in tammar wallabies. In this study, we investigated the concentration of cortisol in fetal fluids and cortisol production by fetal adrenals over the last 3 days of the 26-day pregnancy and within 24 h postpartum. The fetal adrenals almost doubled in size between Days 24 and 26 of pregnancy, and their cortisol content increased over 10-fold during this period, from 10 pg to over 100 pg per adrenal pair. After birth, neonatal adrenals continued to grow, but cortisol content fell dramatically to 20 pg. The prepartum increase in adrenal cortisol was reflected by a substantial rise in cortisol concentrations in yolk sac fluid, allantoic fluid, and fetal blood, which were below 10 ng/ml on Day 24 and rose to over 40 ng/ml by Day 26. Cortisol concentrations in neonatal blood decreased postpartum, mirroring decreased cortisol content in neonatal adrenals. Cortisol production by the fetal adrenal was stimulated in vitro by ACTH and prostaglandin E2, suggesting that the in vivo increase may be stimulated by release of ACTH from the fetal hypothalamic-pituitary axis and prostaglandin E2 from the placenta. These results indicate that increasing cortisol production by the fetal adrenal is a characteristic of late pregnancy in the tammar wallaby and support the suggestion that fetal cortisol may trigger the initiation of parturition in this marsupial species.     

Effect of corticoid induced parturition on lactation and on prepartum profiles of serum progesterone and the estrogens among cows retaining and not retaining fetal membranes

Twenty-one mature F1 Brahman-Hereford cows were treated with 25 mg of dexamethasone (DEX) on day 279 or 280 of gestation to induce birth prematurely. Eigth cows were untreated (UT). Blood was sampled on day 279 or 280 of gestation just prior to treatment of cows with DEX (0 hr), at least daily thereafter to calving and within 1 hr postpartum. Concentrations of progesterone (P₄), estrone (E₁) and estradiol-17β (Eβ) and -17α (Eα) in blood serum were measured by radioimmunoassay. Among 21 cows treated with DEX, 16 (76%) calved within 78 hr (52±3 hr). Eleven of the 16 cows retained fetal membranes more than 12 hr (RFM) and five cows did not retain fetal membranes (NRFM). Five cows (24%) treated with DEX calved 266±46 hr later (NOR) on day 290±1 of gestation compared to day 286±2 for cows in group UT. No cow in groups NOR or UT had RFM. Failure of group NOR to calve prematurely appeared due to elevated serum P₄ (P<.05), low serum Eβ (P<.10) and other estrogens (P>.10) pretreatment, and to only a 32% decrease in serum P₄ within 72 hr after treatment. Serum estrogens, especially Eβ, were next lowest pretreatment in group RFM. However, in group RFM, all serum estrogens increased (P<.10 to P<.01) within 48 hr after treatment, reached higher concentrations and peaked later in relation to calving than in other groups (NRFM, NOR and UT). Synchronization of placental maturation and parturition may require a longer period of elevated serum estrogens prior to calving than was observed in group RFM. Treatment of cows prepartum with DEX had no effect on gain of calves, milk yield or yields of fat, total protein and total solids in milk during the first 12 weeks of lactation.     

Influence of induction of parturition on the neonatal acute phase response in foals

The objectives of the present study were to determine whether induction of parturition in mares at term with low doses of oxytocin (2.5 i.u. i.v. every 20 min) affected the incidence of peri-partum complications or inflammatory responses in the neonatal foal. Parturition was induced in 11 of 26 mares and the remainder foaled spontaneously. Serum concentrations of amyloid A (AA; an acute phase protein) were measured (with a commercial ELISA) from 0 to 72 h postpartum in 18 of the neonatal foals. The incidence of dystocia and premature placental separation was higher in induced mares (2 of 11 and 1 of 11 versus 0 of 15 and 0 of 15, respectively), whereas retained fetal membranes were more common in spontaneous foalings (2 of 15 versus 0 of 11). When abnormal foals were excluded (to decrease the influence of endogenous serum AA elevations), serum concentrations of AA increased to the same extent over time in foals with induced versus spontaneous parturition; foals with spontaneous parturition had a mean serum AA concentration of 7.8 microg/mL at birth that increased to a maximum of 58.9 microg/mL at 36 h; foals with induced parturition had a mean serum AA concentration of 5.4 microg/mL at birth that increased to a maximum of 41.4 microg/mL at 48 h. Baseline serum AA concentrations were lower in induced foals. We concluded that inducing parturition with low doses of oxytocin in mares at term did not affect (relative to spontaneous parturition) the temporal dynamics of serum AA concentrations in the normal foal in the first 72 h of life. However, the induction procedure may lead to complications during parturition that, if not detected early, could result in the development of an inflammatory response in the neonate.     

Signal for term parturition is of trophoblast and therefore of fetal origin

Up to now we know, that cytokines are key intermediates in the mechanisms, responsible for intrauterine activation in case of intra amniotic infection. The aim of our study was to investigate the role of cytokine- and prostaglandin production in normal term labor. Release of Il-6, Il-1β, TNF-, PGE₂, PGF₂ was monitored in vaginal secretions originating from uterine cavity, cervix and vagina during normal course of labor. Cells from fetal membranes, decidua and villous trophoblast, obtained from placentas of patients after spontaneous delivery (n = 12), or without labor, after elective cesarean section (n = 12), were cultured, in order to identify cytokine and prostaglandin producing cells. In all cases, term labor and parturition was associated with strongly elevated cytokine- and prostaglandin concentrations in cervical secretions. Cell culture experiments clearly demonstrated, that cells from villous trophoblast, cultured after spontaneous delivery produced significantly more cytokines and prostaglandins than cells form villous trophoblast, cultured after elective cesarean section. Cells from fetal membranes also produced more Il-6 and PGE2 after labor. In contrast to that, cells from decidua produced similar amounts of cytokines and prostaglandins before and after spontaneuos term labor. Therefore we conclude, that the signal for term labor and delivery is of trophoblast and so of fetal origin.