Estrone concentration in the peripheral plasma of pregnant and non-pregnant gilts

A rapid radioimmunoassay for estrone (total unconjugated and sulfated) was developed to determine plasma estrone (E1) concentrations in inseminated gilts that conceived and those that had not. Thirty-one 160 day-old prepuberal gilts were induced to ovulate with gonadotropins and were artificially inseminated 10 hr before the expected time of ovulation (Day 1 - day of insemination). Unconjugated E1 and E1SO4 were extracted from 20 to 500 microl of plasma twice with 5 ml of tetrahydrafuran:ethyl acetate (1:1). Aliquots of a standard E1SO4 preparation were dissolved in 500 microl of distilled water and extracted at the same time as the plasma samples. The dried extracts were solvolyzed for 1 hr at 50 degrees C in 0.6 ml of glacial acetic acid:ethyl acetate (1:1), and the dried residue was redissolved in 0.2 ml of distilled water and extracted once with 2 ml of diethyl ether. Twenty of 31 gilts were pregnant at Days 29 to 31 of the induced cycle. Plasma E1 in pregnant gilts increased from 85 pg/ml on Day 18 to 702, 1879 and 2793 pg/ml, respectively, on Days 22, 25 and 29 to 31. Three of the non-pregnant gilts had plasma progesterone secretion maintained until Day 22; they also had a transitory increase in plasma E1 on Day 22 (215 pg/ml). Some blastocysts may have been present to exert a temporary luteotropic effect, but not enough blastocysts to completely overcome the luteolytic effect of the uterus. Quantification of plasma E1SO4 could be used as a pregnancy test in the pig.     

In-vitro development of zygotes from superovulated prepubertal and mature gilts

Ten prepubertal and 8 mature gilts were superovulated with PMSG and hCG, and inseminated with fresh boar semen. Zygotes were surgically recovered from oviducts 54-60 h after hCG. One and 2-cell zygotes were randomly allotted to Medium PL (modified BMOC-3 supplemented with 0.1 mM-EDTA and 1.5% BSA) or Medium G (Medium PL without pyruvate or lactate). Eggs were washed twice in medium, and placed in microdrops of medium overlaid with silicon oil for culture in an humidified 5% CO2, 5% O2, 90% N2 environment, then observed daily for 6 days. Development of eggs was dependent (P less than 0.001) on the interactive effects of age of gilt (prepubertal versus mature) and medium type (PL versus G) used in culture. A greater proportion of eggs cultured in Medium G developed further than did eggs in Medium PL (P less than 0.001). Additionally, a greater proportion of eggs from mature gilts developed further than did eggs from prepubertal gilts (P less than 0.02). We suggest that these results provide evidence that zygotes resulting from superovulation regimens of prepubertal gilts do not possess the same capacity for in-vitro development as do zygotes from pubertal gilts.     

Ultrasonographic characterization of the ovaries in non-pregnant first served sows and gilts

This study was aimed firstly, to examine the ovaries in non-pregnant first served sows and gilts by transcutaneous ultrasonography and secondly, to evaluate the suitability for this procedure to be performed routinely on farms. Two thousand five hundred and twenty-three females on a 1250-sow unit, synchronized with Regumate (gilts only) and/or gonadotropins (sows and gilts) not detected as returned to estrus by daily boar contact prior to scanning were ultrasonographically tested for pregnancy between days 20 and 114 postinsemination (p.i.). Of 256 sows (S) and 130 gilts (G) found to be non-pregnant the ovaries were visualized in 87.1 and 80.0% of them, respectively. Ovarian findings were: corpora lutea (CL); follicles of 2-6mm (F(2-6)); peri-ovulatory ovarian structures (POS; comprising follicles of 7-8mm and corpora haemorrhagica); single cysts (SC); oligocystic ovarian degeneration (OOD) and polycystic ovarian degeneration (POD). Their incidence was: CL>F2-6>POS>POD ( P<0.05 ) in both S and G. POD and SC plus OOD were more frequently in S ( P<0.05 ). The ovarian findings were related to the intervals of regular (days 18-25 p.i. (R1), 38-46 p.i. (R2)) and irregular service returns (days 26-37 p.i. (IR1), 47-114 p.i. (IR2)). Comparison within intervals: CL tended to be more frequently with P<0.05 only at IR2 in S. Comparison among intervals (R1 to IR2): The percentage of females (1) with CL tended to increase (S and G) and (2) with F2-6 plus POS decreased significantly (S; P<0.05 ) or tendentiously (G). SC plus OOD was higher before R2, POD after IR1 (S and G; P<0.05 ). In conclusion, the results indicate a high heterogeneity of ovarian structures in non-pregnant first served sows and gilts up to day 114 after service and suggest CL as an important cause for a delayed and, rather than POD, a failed service return. The results further demonstrate that transcutaneous ultrasonography is an appropriate and recommended method for examining the ovaries on farm in female pigs with reproductive failures.     

Inhibition of pregnancy with indomethacin in mature gilts and prepuberal gilts induced to ovulate

Twenty prepuberal (P) gilts, 56.5 +/- 1.1 kg body weight, were induced to ovulate with 1000 IU of pregnant mare's serum gonadotropin followed 72 h later by 500 IU of human chorionic gonadotropin (hCG), and bred by artificial insemination (AI) with 50 ml fresh pooled boar semen the day after hCG treatment (Day 0). Eighteen mature (M) gilts, 120.6 +/- 1.7 kg body weight, were bred by AI each day of estrus using pooled semen from the same boars (onset of estrus = Day 0). One-half of each group was fed the prostaglandin (PG) synthesis inhibitor indomethacin (IND), at 10 mg/kg body weight, or control (C) feed twice daily on Days 10 to 25. Blood samples taken by venipuncture on Days 10, 15, 20 and 25 were quantitated for progesterone (P4) and 13,14-dihydro-15-keto-PGF2 alpha (PGFM) by radioimmunoassay. Ovaries were examined on Day 26. All M-C gilts were pregnant, whereas 3 of 9 M-IND gilts (P less than 0.05) and none of the P gilts (P less than 0.01) were pregnant. Three of the 6 nonpregnant M-IND gilts displayed estrus on Day 21. The 3 remaining M-IND gilts had maintained corpora lutea (CL) on Day 26. Only corpora albicantia were present in P gilts on Day 26. Serum P4 concentrations for M-C gilts, nonpregnant M-IND gilts with maintained CL, and pregnant M-IND gilts were not different. Serum P4 for all nonpregnant gilts in which CL had regressed by Day 25 decreased to less than 5 ng/ml on Day 20.(ABSTRACT TRUNCATED AT 250 WORDS)     

Acid phosphatase and leucine aminopeptidase activity in the uterine flushings of non-pregnant and pregnant gilts

The activities of uteroferrin, measured as acid phosphatase (AP), and an aminoacylpeptidase (AA) were measured in uterine flushings collected from gilts on Days 6, 8, 10, 12, 14, 15, 16 and 18 of the oestrous cycle and pregnancy (N = 37). Changes in AP (P less than 0.05) were associated with day for both specific and total AP in non-pregnant and pregnant gilts. For pregnant and non-pregnant gilts, AP activity was greatest between Days 14 and 16 and then decreased to Day 18. The AA specific activity increased (P less than 0.01) between Days 10 and 12 of the oestrous cycle and pregnancy, but neither effects of pregnancy nor day by pregnancy status interaction were detected. The AA total activity was greater for pregnant gilts (P less than 0.01). These data suggest an inhibitory effect of oestrogens of blastocyst origin on synthesis and/or secretion of uteroferrin, but not AA.     

The effects of zearalenone on reproduction in swine. I. The relationship between ingested zearalenone dose and anestrus in non-pregnant, sexually mature gilts

Ninety-nine sexually mature, non-pregnant gilts were checked for estrus daily with a mature boar and then allocated at estrus (D O) to receive 2 kg/d of a diet containing 0, 1, 5 or 10 ppm purified zearalenone between D 5 and 20 of the estrous cycle during two seasons of the year (winter and summer). None of the gilts exhibited any visual signs of "hyperestrogenism" and there was no effect of season on interestrous interval (P > 0.05). A significant effect of zearalenone dose on inter-estrous interval was detected (P < 0.001). Gilts receiving 0 or 1 ppm had similar inter-estrous intervals (21.0 +/- 0.3 and 21.5 +/- 0.8 d, respectively) whereas gilts receiving 5 and 10 ppm had extended cycles (29.2 +/- 2.9 and 32.7 +/- 3.3 d, respectively). Plasma progesterone concentrations at D 19 to 21 were higher in gilts with extended cycles (P < 0.001) and corpora lutea (CL) were present at laparotomy. Some 86% of these retained CL underwent spontaneous regression resulting in the onset of estrus within the next 30 d. Fecal zearalenone concentrations rose during ingestion of contaminated diets and declined to pretreatment values within 2 d (1 ppm) to 8 d (10 ppm) of the cessation of treatment. These data show that feeding zearalenone at concentrations of 5 to 10 ppm from D 5 to 20 of the estrous cycle causes luteal maintenance and extended inter-estrous intervals. Spontaneous regression of these CL usually occurs within 30 d after zearalenone is removed from the diet. Fecal zearalenone analysis does not appear to be an effective method for determining prior exposure to zearalenone when carried out more than a few days following the last ingestion of zearalenone.     

Influence of the presence of a mature female on puberty attainment in gilts

At 90 days of age, 40 Large White gilts were assigned to one of two treatments. At 155 days, a mature female which was left intact (Treatment I) or ovariectomized (Treatment O) was placed in each pen of five experimental gilts. From 180 days, estrus was checked daily with the back pressure test, and the occurrence of ovulation was detected by measuring the concentration of plasma progesterone at weekly intervals. From 240 days, a mature boar was introduced, for 5 minutes daily, into each pen during estrus detection. Gilts were slaughtered within 12 days after ovulation or at 270 days of age if they were not cyclic earlier. The percentage of gilts reaching puberty before 225 days of age was significantly higher in Treatment I (7 19 ) than in Treatment O (0 19 ) even though the average age at puberty was similar (I, 231 +/- 24 days; O, 243 +/- 12 days; mean +/- SD). Age at puberty and the number of days between mature female introduction and puberty differred significantly between the pens of gilts in Treatment O but not in Treatment I. Ovarian weights, ovulation rate and percentage of gilts with silent estrus were similar in the two treatments. Thus, the occurrence of pubertal estrus may be influenced by contact with an older, cyclic female or with other contemporary females raised in the same pen.     

Serum concentrations of prolactin, oestrogen and LH during the perioestrous period in prepubertal gilts induced to ovulate and mature gilts

The temporal relationships of serum prolactin, oestrogen and LH concentrations during the perioestrous period were compared in prepubertal gilts induced to ovulate by PMSG and hCG and in mature gilts. In Exp. 1, 2 sustained prolactin surges, beginning 4 days and 1 day before the preovulatory LH surge, occurred in all mature gilts. A single preovulatory prolactin surge occurred in 3 prepubertal gilts, starting just before the preovulatory LH surge, but 4 prepubertal gilts had neither a prolactin nor an LH surge. A status (prepubertal or mature) versus time interaction (P less than 0.01) was detected for serum prolactin concentrations. A preovulatory oestrogen surge occurred in all gilts but was of lesser magnitude (P less than 0.01) and duration (P less than 0.05) in the prepubertal gilts without prolactin and LH surges compared to mature gilts and of lesser magnitude (P less than 0.01) compared to prepubertal gilts with prolactin and LH surges. The relative timing of the oestrogen surge in prepubertal gilts corresponded with that of mature gilts when adjusted to the LH surge (if present) but was delayed (P less than 0.01) in all prepubertal gilts if standardized to the hCG injection. In Exp. 2, mature gilts were examined to determine whether 2 perioestrous prolactin surges were characteristic of all cycling gilts. Of 9 gilts, 8 exhibited an initial prolactin surge 4-5 days before oestrus and 5/9 gilts exhibited a periovulatory prolactin surge. The presence of 2 perioestrous serum prolactin surges was not a requirement for subsequent pregnancy maintenance.(ABSTRACT TRUNCATED AT 250 WORDS)     

Synchronization and superovulation of mature cycling gilts for the collection of pronuclear stage embryos

An efficient protocol was developed to synchronize and superovulate mature pigs for the collection of pronuclear stage embryos suitable for DNA microinjection. A timed and coordinated regimen of Lutalyse, PG600 and Chorulon along with daily checking for estrus allowed synchronization of groups of gilts having estrous cycles at regular intervals. Pigs 10-16 days after the beginning of standing estrus have been successfully synchronized into estrus using this protocol. A standard dose of each drug was used independent of size or age of the animal. One protocol averaged 38.9 ovulations and 31.1 one-cell embryos recovered per animal.     

Expression of chemerin and its receptors in the ovaries of prepubertal and mature gilts

Recent studies have demonstrated that chemerin participates in the regulation of female reproductive function at the level of the ovaries. Due to the lack of data concerning the presence of the chemerin system (chemerin and its receptors: CMKLR1, GPR1, CCRL2) in the ovaries of pigs, one of the most economically important livestock species, the aim of this study was to investigate the expression and localization of chemerin and its receptors in the ovaries of prepubertal and mature gilts. We also aimed to examine the concentrations of chemerin in the follicular fluid of prepubertal and mature animals. In the present study, we have demonstrated the expression patterns of chemerin system components in the porcine follicles of different sizes of prepubertal and mature animals, as well as in corpora lutea of mature gilts during the estrous cycle and early pregnancy. The obtained results suggest that the expression of chemerin system components is influenced by the reproductive stage, cell type, and the hormonal status of gilts (the estrous cycle/pregnancy). We have also presented the localization of the chemerin system components in various ovarian structures, and also showed changes in the concentration of chemerin in the follicular fluid of pigs. The presented findings not only confirm that chemerin is produced locally in the porcine ovary but they also demonstrate that chemerin directly affects ovarian cells, as confirmed by the presence of chemerin receptors in all ovarian structures. Therefore, chemerin appears to be an important intra‐ovarian factor that could regulate ovary function in pigs.     

Prostaglandin F concentrations in utero-ovarian vein plasma of prepuberal and mature gilts

Prostaglandin F (PGF) and progestins in utero-ovarian vein (UOV) plasma during the late luteal phase of the estrous cycle in unbred mature gilts and following induced ovulation in unbred prepuberal gilts were determined. Prepuberal gilts (120 to 130 days of age) were induced to ovulate with Pregnant Mare Serum Gonadotropin and Human Chorionic Gonadotropin (HCG). The day following HCG was designated as Day 0. Mature gilts which had displayed two or more estrous cycles of 18 to 22 days (onset of estrus = Day 0) were used. Polyvinyl catheters were inserted into the UOV of all gilts and blood was collected at 15 min intervals from 0800 to 1045 hr on Days 10 through 20 or Days 12 through 18. Plasma PGF concentrations in the mature gilts were elevated on Days 13, 14, 15, 16 and 17, whereas, plasma PGF concentrations in the prepuberal gilts were elevated only on Days 15, 16 and 17 resulting in a reproductive age (mature vs prepuberal) by day interaction (P<.01). In addition, the PGF concentrations on Days 13 through 17 were consistently greater in the mature gilts than in the prepuberal gilts as was the overall mean PGF concentration (1.95 vs .83 ng/ml). The average peak PGF concentration throughout the sampling period (4.6 vs 2.5 ng/ml; P<.01) and the average peak PGF concentration prior to luteal regression (3.8 vs 1.1 ng/ml; P<.05) were also greater in the mature than in the prepuberal gilts. Based on these results, we suggest that luteal regression in the bred prepuberal gilt following induced ovulation may not be due to an excessive production of the uterine luteolysin, but rather that the induced corpora lutea (CL) of the prepuberal gilt may be more sensitive to the uterine luteolysin than the spontaneously formed CL of the mature gilt.     

Bacterial translocation from the intestines

Bacterial translocation is defined as the passage of viable bacteria from the gastrointestinal (GI) tract through the mucosal epithelium to other sites, such as the mesenteric lymph nodes, spleen, liver and blood. This paper reviews results from animal models utilized to obtain information concerning the defense mechanisms operating in the healthy host to confine bacteria to the GI tract. Gnotobiotic and antibiotic-decontaminated mice colonized with particular bacteria demonstrated that the indigenous GI flora maintains an ecologic equilibrium to prevent intestinal bacterial overgrowth and translocation from the GI tract. Studies with athymic (nu/nu) mice, thymus-grafted (nu/nu) mice, neonatally thymectomized mice, and mice injected with immunosuppressive agents demonstrated that the host immune system is another defense mechanism inhibiting bacterial translocation from the GI tract. Ricinoleic acid given orally to mice disrupted the intestinal epithelial barrier allowing indigenous bacteria to translocate from the GI tract. Thus, bacterial translocation from the GI tract of healthy adult mice is inhibited by: (a) an intact intestinal epithelial barrier, (b) the host immune defense system, and (c) an indigenous GI flora maintaining ecological equilibrium to prevent bacterial overgrowth. Deficiencies in host defense mechanisms act synergistically to promote bacterial translocation from the GI tract as demonstrated by animal models with multiple alterations in host defenses. Bacterial translocation occurred to a greater degree in mice with streptozotocin-induced diabetes, mice receiving nonlethal thermal injury, and mice receiving the combination of an immunosuppressive agent plus an oral antibiotic than in mice with only a primary alteration in host defenses. The study of bacterial translocation in these complex models suggests that opportunistic infections from the GI tract occur in discrete stages. In the healthy adult animal, bacterial translocation from the GI tract either does not occur or occurs at a very low level and the host immune defenses eliminate the translocating bacteria. Bacterial translocation does take place if one of the host defense mechanisms is compromised, such as a deficiency in the immune response, bacterial overgrowth in the intestines, or an increase in the permeability of the intestinal barrier. In this first stage, the bacteria usually translocate in low numbers to the mesenteric lymph node, and sometimes spleen or liver, but do not multiply and spread systemically.(ABSTRACT TRUNCATED AT 400 WORDS)     

Relationship between the spike activities of the small and large intestines

Experiments were performed using chronically implanted electrodes on the dog smooth muscle wall of the stomach and of the small and large intestines. Electrical activity of the muscle wall was recorded before and after feeding. When reaching the terminal ileum the active part of the migrating myoelectrical complex (MMC) continuously induced bursts of spike potentials superimposed on the slow waves. This electrical activity spread to the ascending colon. We also showed the existence of a spike activity on the terminal ileum independent of the MMC (appearing during the phase 1) and propagating to the colon. A relationship between the spike activities of the small and large intestines was also present after feeding. Beside the well-known gastro-colic reflex, we observed an increase in the spike activity of the terminal ileum and ascending colon between the 4th-5th hours after feeding. This probably corresponds to the arrival of the first portions of contents, evacuated from the arrival of the first portions of contents, evacuated from the stomach, and of the last portions of small intestinal contents. In conclusion, there is a relationship between the spike activities of the small and large intestines in starving animals and after feeding, and the terminal ileum plays a substantial role in this relationship.     

Absorption of Escherichia coli endotoxin (lipopolysaccharide) from the uteri of postpartum dairy cows

An experiment was conducted to test the hypothesis that Escherichia coli (E. coli ) endotoxin is readily absorbed from uteri of early postpartum cows and that the absorbed endotoxin provokes systemic relcase of prostaglandins. Eleven postpartum Holstein dairy cows (aged 3 to 7 yr) with normal puerperium were selected and divided into a treatment group (n=7), which received intrauterine infusions of E. coli endotoxin, and a control group (n=4), which received intrauterine infusions of 10 ml of saline on Days 5 and 20 post partum. Blood samples were collected once every 30 min for 6 h starting from the time of infusion. Harvested sera samples were analyzed for concentrations of stable metabolites of prostacyclin (PCM), prostaglandin F(2alpha) (PGFM), and thromboxane A(2) (TXB(2)). Plasma samples were qualitatively tested for the presence of endotoxin. Endotoxin was detected in the plasma samples of cows that received endotoxin on Day 5 post partum 4 h after the infusion. Endotoxin was not detected in any of the samples from control cows on Days 5 and 20 post partum or from treatment group cows on Day 20 post partum. Cows treated on Day 5 post partum showed increases in serum PGFM concentrations from 710 +/-64pg/ml to peak concentrations of 1223 +/- 47 pg/ml within 2 h, followed by a decline to baseline concentrations within 4 h. The amount of PGFM released in treated cows on Day 5 post partum was higher (P < 0.05) than in control cows on Day 5 or in treated and control cows on Day 20 post partum. Serum PCM concentrations increased from 156+/-24 pg/ml to peak concentrations of 1348+/-127 pg/ml within 1 h. The amount of PCM released in treated cows on Day 5 postpartum was higher (P< 0.05) than in control cows on Day 5 or in treated and control cows on Day 20 post partum. The TXB(2) concentrations increased from 315+/-38 pg/ml to peak concentrations of 5043 +/- 242 pg/ml within 1 h and fell to baseline concentrations within 5 h. The amount of TXB(2) concentrations released in treated cows on Day 5 post partum was significant (P < 0.05) compared with those of cows in the other groups. The results support the hypothesis that uteri of early postpartum cows are capable of absorbing endotoxin, and the absorbed endotoxin provokes changes in the serum concentrations of prostanoids.