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.     

Evidence for prostaglandin involvement in early luteal regression of the superovulated nanny goat (Capra hircus)

Feral does of various ages were treated with intravaginal progestagen sponges for 16 days to synchronize oestrus. On Day 2 before sponge removal the goats were given 1200 i.u. PMSG to induce superovulation: 6 of the goats were also injected every 12 h with flunixin meglumine, a prostaglandin (PG) synthetase inhibitor, from Day 3 to 7 of the synchronized oestrous cycle. Jugular blood samples were collected from all females into heparinized syringes at daily intervals over the 2 days before sponge removal, twice daily for the next 2 days, then at hourly intervals from 09:00 to 17:00 h for 2 days and then twice daily for a further 2 days, for measurement of plasma progesterone and the PGF metabolite 13,14-dihydro-15-keto-PGF (PGFM) by radioimmunoassay. Intermittent surges in plasma PGFM concentrations were observed in hourly samples collected from 4/4 untreated females but in only 2/6 of the inhibitor-treated females (P less than 0.05), and the peak plasma PGFM concentrations were reduced in these 2 inhibitor-treated goats compared with the control goats. The corpora lutea (CL) of the inhibitor-treated females appeared to be functional as indicated by the plasma progesterone profile and endoscopic examination of CL. In the control females, however, there was evidence of premature regression of CL. These results suggest that the premature release of PGF-2 alpha may be the cause of premature regression of CL in nanny goats induced to superovulate.     

Changes in concentrations of follistatin in maternal plasma and foetal fluids during pregnancy and parturition in sheep

Studies have shown that follistatin may be involved in the regulation of ovarian development, pregnancy and parturition. The aim of the present study was to measure follistatin levels in maternal plasma and foetal fluids during pregnancy and parturition in sheep. Using a previously described follistatin radioimmunoassay, we found that follistatin in foetal plasma and allantoic fluid was higher in the female than in the male at days 50-75 of gestation. Follistatin concentrations in maternal plasma declined from -9 to -3h before the completion of lamb delivery, and increased from 21 to 39 h after parturition. These results suggest that follistatin may play a role in femaleness development, and that follistatin may be involved in the mechanism of normal parturition and in regulation of the tissue repair after parturition.     

Foetal loss in dairy goats: function of the adrenal glands, corpus luteum and the foetal-placental unit.

To investigate the causes and mechanisms of foetal loss in Norwegian dairy goats, blood parameters in 40 goats that lost foetuses were compared with those in 40 goats that experienced a normal pregnancy. High mean levels of 15-ketodihydro-PGF2alpha, and low mean levels of oestrone sulphate throughout pregnancy were associated with foetal loss. The mean oestrone sulphate level was low before abortion, and the distinct peak that occurred at parturition in the control goats was not observed in connection with abortion. Association of other blood parameters with foetal loss was not detected. Infectious agents and toxins did not appear to be major causes of foetal loss in this study. The normal level of progesterone and cortisol in goats with foetal loss indicated that the function of the corpus luteum and adrenal glands, respectively, were not disturbed. The rapid decline in progesterone level associated with foetal loss may therefore be a result, rather than the cause, of foetal death. The lowered level of oestrone sulphate and elevated level of 15-ketodihydro-PGF2alpha in goats with foetal loss clearly indicated that the endocrine foetal-placental function was disturbed.     

Milk fat progesterone concentrations in goats and early pregnancy diagnosis

Blood and milk samples from foremilk during afternoon milking, were simultaneously collected from 285 dairy goats. In experiment 1, fiva cyclic goats were sampled daily for 21 days. In experiment 2, 280 females from 9 flocks were submitted to sampling 21 days after insemination. In addition, some milk samples were divided in two parts, after which one was frozen and the other kept at +4 degrees C until assay. Progesterone concentrations were measured in blood, whole milk and milk fat by radioimmunoassay. No difference in whole milk or fat progesterone levels was found between frozen and refrigerated milk samples. Milk butterfat progesterone concentrations paralleled those in plasma or whole milk throughout the estrous cycle and ranged from about 20 ng/ml at estrus to about 400 ng/ml in mid-luteal phase. The ratio of mid-luteal phase progesterone levels to those seen in the estrous period was over 20 in fat and in blood. This ratio was very much lower in whole milk. Consequently the determination of pregnant and non-pregnant goats from the samples collected 21 days after service was very much easier and accuracy was better when the progesterone content was assayed from milk fat than from whole milk. It was concluded that early pregnancy diagnosis in goats can be done routinely by determination of progesterone levels in milk fat.     

Relation between progesterone concentrations during the early luteal phase and follicular dynamics in goats

We studied the relationship between progesterone (P4) concentrations early in the estrus cycle and follicular dynamics in dairy goats. We used seven untreated goats (control group) and six progesterone treated goats (P group) with a controlled internal drug release device from Days 0 to 5 (Day 0: day of ovulation). We performed daily ultrasonograph during the interovulatory interval to determine ovarian change and took daily blood samples to determine serum estradiol 17beta (E2) and P4 concentrations by RIA. We divided the control goats into 3- (n = 4) and 4-wave goats (n = 3), according to the number of follicular waves recorded during the ovulatory cycle. Mean progesterone concentrations between Days I and 5 were higher and mean estradiol concentrations between Days 3 and 5 were lower in 4-wave goats (P4: 3.8+/-0.2 ng/ml; E2: 1.6+/-0.2 pg/ml) than in 3-wave goats (P4: 2.0+/-0.5 ng/ml, P < 0.05; E2: 4.4+/-0.9 pg/ml, P < 0.05). Wave 2 emerged earlier in 4-wave (Day 4.2+/-0.3) than in 3-wave goats (Day 7.3+/-0.3, P < 0.05). Three out of six of the progesterone-treated goats had short cycles (mean 8.0+/-0.0 days) and ovulated from Wave 1. The other three goats had shorter cycles (mean 18.3+/-0.3 days) than the control group (20.0+/-0.2 days; P < 0.05), although they were within the normal range of control cycles (shortened cycles). In the three treated goats with shortened cycles (two with four waves, one with three waves), mean progesterone concentrations between Days I and 5 were higher (4.7+/-0.6 ng/ml) than in the 3-wave control goats. In these goats, Wave 2 emerged at Day 4.3+/-0.3, similar to the time observed in 4-wave goats but earlier (P < or = 0.05) than in 3-wave control goats. Overall results confirm a relationship between the progesterone levels and the follicular wave turnover during the early luteal phase in the goat. Higher progesterone concentrations may accelerate follicular turnover probably by an early decline of the negative feedback action of the largest follicle of Wave 1. This is followed by an early emergence of Wave 2.     

Pregnancy-specific protein B and progesterone concentrations in French Alpine goats throughout gestation.

The 34 French Alpine dairy goats originated from a single flock and were artificially inseminated 44 h after synchronization of oestrus. They were bled daily at the jugular vein from 15 to 27 days after AI. An early pregnancy diagnosis by RIA of progesterone concentration was performed 21 days after AI. In pregnant goats (greater than 1.5 ng progesterone/ml) daily sampling was extended until 30 days after AI and, from those, 9 were bled every 2 weeks until the end of pregnancy and at 50 and 63 days post partum. Pregnancy-specific protein B (PSPB) was also assayed. The kidding rate was 67.6% (23/34). PSPB concentrations (ng/ml) in pregnant goats were significantly different from those of non-pregnant goats at 24 days after AI (0.82 +/- 0.18 vs 1.78 +/- 0.19; mean +/- s.e.m.) and rose to 40 ng/ml at the end of pregnancy. From Day 25 and throughout gestation, females with 2 fetuses had higher PSPB concentrations than did those with a single fetus (P less than 0.05). In the 2 goats exhibiting late embryonic mortality according to progesterone concentrations, one had a PSPB profile very similar to those of pregnant goats until 30 days while the other did not show any elevation of PSPB concentration. It is concluded that PSPB profiles in goats are similar to those found in cows throughout pregnancy and that PSPB RIA may be useful for pregnancy diagnosis or diagnosis of late embryonic mortality.     

Plasma prolactin variations and onset of ovarian activity in lactating anestrous goats given melatonin

This experiment was carried out in order to investigate the effects of melatonin treatment on prolactin plasma levels and the onset of cyclicity in anestrous goats. Fifty lactating goats were treated daily with 2.5 mg melatonin (i.m.) from 6 June to 18 September and fifty goats served as a control. The progesterone and prolactin plasma concentrations were determined by radioimmunoassays on blood samples collected once a week until the end of September. The onset of ovarian activity (monitored by the plasma progesterone determination) was advanced in the melatonin-treated does by about one week compared with the controls. Prolactin plasma levels decreased in the control animals from the highest concentrations observed in June to the lowest near the end of the experiment. In the melatonin-treated goats, the prolactin plasma levels dropped after the beginning of the treatment and remained significantly lower than those of the untreated does for about two months; from then onwards, no differences were observed between the two groups until the end of the experiment.     

The onset of mammary extraction of plasma triglycerides and circulating levels of progesterone during lactogenesis in the cow and goat

In untreated cows and goats, the onset of mammary extraction of plasma triglyceride was sometimes detected several hours before parturition, prior to removal of secretion from the mammary glands by offspring and when circulating progesterone concentrations were low. In cows and goats that had secretion regularly removed from the mammary glands late in gestation, the onset of triglyceride extraction occurred up to several days before parturition, when circulating progesterone concentrations were moderately high (up to 3.9 ng/ml in the cow and 6.2 ng/ml in the goat).     

The role of endogenous estrogens in the maturation process of the bovine placenta

The plasma estrogen and progesterone concentrations of 19 pregnant cows (average duration of pregnancy 266.0 +/- 2.3 d at the start of the study) were determined daily from Day 6 pre partum to Day 1 post partum. Parturition was induced in all cows by administration of 10 mg i.m. flumethasone. Values were centered around the delivery date (Day 0) following either induced normal calving (n = 3) or surgical delivery (n = 16). In animals showing spontaneous expulsion of the fetal membranes (Group 1, n = 6) the average total estrogen concentration increased significantly from Day 6 until Day 1 before parturition (1329.2 +/- 317.9 to 3719.8 +/- 951.2 pg/ml in total estrogens). A marked decrease was observed on Day 1 post partum (459.4 +/- 344.2 pg/ml). In comparison with Group 1, animals showing either a delayed or partial expulsion of the fetal membranes, or in which the placenta could be withdrawn 16 h after calving (Group 2, n = 5), had consistently lower total estrogen concentrations between Day 6 (595.4 +/- 174.8 pg/ml) and Day 1 (1884.3 +/- 565.1 pg/ml) before parturition. The estrogen values of the cows with retained placenta (Group 3, n = 8) from Days 6 to 0 pre partum were significantly lower than those of Group 2. Total estrogen concentrations of the three groups 1 d post partum did not differ significantly. It is generally recognized that estrogens play an important role in the maturation process of the placentomes. Our investigation demonstrates that not only is the magnitude of the prepartum rise in estrogens of great influence of the maturation process but the duration of this rise is likewise important. These two factors are vital for a normal expulsion of the fetal membranes.     

Effect of high progesterone concentrations during the early luteal phase on the length of the ovulatory cycle of goats

The effect of exogenous progesterone exposure early in the oestrous cycle on the duration of the interovulatory interval was studied in dairy goats. A controlled intravaginal drug release (CIDR-G) device was inserted for 5 days starting at day 0 (D0 group, n=6) or day 3 (D3 group, n=5) postovulation. A third group was composed of untreated control goats (control group, n=7). Daily transrectal ultrasound was carried out during the interovulatory interval to assess the ovarian dynamics. Oestrous behaviour was checked twice a day and serum progesterone levels were assayed in daily jugular blood samples. Treated goats showed two different responses. In three D0 goats and one D3 goat, progesterone concentrations fell immediately after CIDR withdrawal and this was followed by oestrus and ovulation between days 8 and 11 (short cycles). In the other three D0 goats and in four D3 goats the treatment significantly reduced the interovulatory interval (18.3+/-0.3 and 18.5+/-0.3 days, respectively) (shortened cycles) compared with the control group (20.0+/-0.2 days; P<0.05), but the intervals with progesterone concentrations over 1 ng/ml were not different (15.7+/-0.3, 15.8+/-0.7 and 16.0+/-0.5 days for D0, D3 and control goats, respectively). In all D0 goats with a short cycle response, the ovulatory follicle arose from the first follicular wave but in the D3 goat with a short cycle it arose from the second follicular wave. These results showed that premature progesterone exposure early in the ovulatory cycle of the goat affected its length inducing short or shortened cycles. The effect of progesterone could either affect luteotropic support of the corpus luteum (CL) and/or stimulate a premature release of the luteolysin.     

Peripheral plasma levels of progesterone in pregnant goats and in pregnant goats treated with prostaglandin F2a

Prostaglandin or prostaglandin analogues have been shown to be luteolytic in the pregnant goat. In this study the temporal changes in the plasma concentrations of progesterone during pregnancy and after administration of PGF2a to pregnant goats are described. PGF2a administration to pregnant goats at 30 and 65 days after breeding induced abortion within 34 to 75 hours. These abortions were accompanied by estrus and profuse muco-hemorrhagic discharges. When PGF2a was administered to pregnant goats 140 or 142 days after breeding, premature parturition occurred within 42 to 76 hours. Live kids were delivered in all cases. The plasma levels of progesterone in all pregnant goats showed dramatic decreases within 24 hours after the prostaglandin injections and continued to decrease gradually until abortions or premature parturition. Thereafter, the progesterone levels remained low for several days.     

Influence of ACTH secreting tumor (MtTF4) on fetal rat adrenal gland steroidogenesis in vitro in prolonged pregnancy

Pregnant female rats with ACTH secreting tumor (MtTF4) have prolonged pregnancy and cannot deliver. The fetuses of tumor bearing females have in prolonged pregnancy on days 24 and 25 of pregnancy greater body weight and smaller adrenal weight as compared to intact fetuses of the 22nd day of pregnancy. The fetal adrenal glands converted to vitro 4-14C progesterone to radioactive 11-deoxycorticosterone (DOC), corticosterone (B), 18-hydroxy-11-deoxycorticosterone (18-OH-DOC), 18-hydroxy-corticosterone (18-OH-B) and aldosterone. Fetal adrenal glands in prolonged pregnancy synthetized in vitro less amount of radioactive DOC, B and 18-OH-DOC. A negative relationship exists between the maternal corticosterone which passes the placenta to fetuses and corticosteroidogenesis of fetal adrenal glands. These results indicate the possibility that fetal rat adrenal glands with their corticosteroids participate in pregnancy and influence normal delivery.     

Plasma progesterone and aldosterone in pregnancy.

Plasma progesterone, aldosterone and renin activity were measured simultaneously in seven women during normal pregnancy. Beginning at the 2nd trimester and until approximately 4 weeks before delivery there was a constant increase in plasma progesterone concentration. There was a significant correlation between weight gain and duration of pregnancy and between weight gain and plasma progesterone concentration. There was also an increase in plasma aldosterone concentration although this was less consistent than that of progesterone. And there was a significant correlation between plasma progesterone and aldosterone concentrations and between the progesterone/aldosterone ratio and duration of pregnancy and weight gain.     

Ovarian and adrenal function during the estrous cycle of the sow.

The concentrations of plasma estrogens, progesterone, and corticosteroids and of urinary pregnanediol, pregnanetriol, ketogenic steroids, and corticosteroids were determined as indicators of ovarian and adrenal function throughout a normal sow's estrous cycle. Two broad peaks of plasma estrogen, one lasting 11–12 days during estrus and another 6-day peak period during the early part of the luteal phase were detected. Plasma progesterone was elevated during the late follicular and luteal phase. Two broad peaks of plasma corticoids appeared, one following the decrease of plasma progesterone and the second 7–14 days later. Those elevations in plasma corticoids occurred when estrogen titres were elevated. Urinary determinations generally reflected plasma findings. Estrogen levels began to rise during the follicular phase while a reasonably high progesterone level was evident. Estrogen titres never decreased to non-detectable levels. An interrelationship between adrenal function and ovarian estrogen production is suggested.     

Pregnancy associated glycoproteins (PAG) in postpartum cows, ewes, goats and their offspring

Determination of plasma concentrations of pregnancy associated glycoproteins (PAG) has been used for early pregnancy diagnosis in cows. However, this is complicated by the presence of PAG in plasma for an extended period postpartum. The main objective of the present study was to investigate the postpartum elimination rates of pregnancy associated glycoproteins (PAG) in sheep, goats and cows in order to gain background information applicable to the use of PAG for pregnancy diagnosis in domestic ruminants. A second objective was to investigate whether PAG are transferred to the foetus and newborn, by measuring plasma PAG concentrations in calves, lambs and goat kids before and after colostrum feeding. PAG in the blood at parturition were eliminated by a first order process in the cows and ewes, while a two-step log-linear decline occurred in the goats. Estimated postpartum half-life of plasma PAG in the cows and ewes was 9 and 4.5 days, respectively. In the goats, half-lives were 3.6 and 7.5 days in the initial fast and terminal slow phase. Basal levels were reached 80-90 days postpartum in cows. Plasma PAG concentration can be used for pregnancy diagnosis from day 28 after AI, provided that the time interval from calving to AI is >60 days. Using a heterologous antibody RIA, we found 4 ng/mL to be the appropriate cut-off. Due to the presence of PAG residues from the previous gestation, the interval from AI to pregnancy diagnosis should increase by approximately 0.5 days beyond 28 days for each day of AI closer to calving than 60. Measurements in newborn ruminants suggested that PAG enter the foetal blood in utero and that colostral PAG are transferred to the newborn. Following the peak plasma concentration observed 1 day after birth in most of the animals, PAG were rapidly eliminated in a log-linear fashion.     

Effect of oxytocin on plasma concentrations of 13,14-dihydro-15-keto-prostaglandin F2 alpha during the oestrous cycle and early pregnancy in the goat.

The effect of subcutaneous oxytocin on plasma concentrations of 13,14-dihydro-15-keto-prostaglandin (PG) F2 alpha (PGFM) was examined in the goat at various periods during the oestrous cycle and early pregnancy. 100 i.u. oxytocin was administered daily for 4 day, the dose being divided and given at 0900 and 2100 h; PGFM concentrations were assessed after the first treatment of each day. On days 3-6 (oestrus, day 0) PGFM concentrations increased significantly (P less than 0.001) within 15 minutes and both non-pregnant and mated goats exhibited oestrus behaviour by day 7. Significant (P less than 0.01) increases in PGFM were also produced on days 7-10, in both non-pregnant and pregnant goats, but the responses diminished from day 7 to day 10; only one goat (non-pregnant) came into oestrus. There was a marked difference in response between groups, however, during days 12-15. In non-pregnant goats significant (P less than 0.05) increases in PGFM were detected on days 13-15, but in pregnant animals oxytocin was without effect. Similarly, oxytocin did not increase PGFM concentrations on days 17-20 of pregnancy. However, uterine responsiveness reappeared in pregnant goats with significant (P less than 0.01) increases in PGFM on days 24 and 25.     

Plasma corticosterone concentrations in the perinatal rat

1. Plasma corticosterone concentrations were determined in the foetal rat during the gestational period from day 18·5 to term and in postnatal rats over the first few hours after delivery. 2. The plasma corticosterone concentrations in foetal rats are as high as six times maternal values at day 19 of gestation and are approximately equal to maternal values from day 20 to term. 3. In postnatal rats the plasma corticosterone concentrations rise 3·5-fold on average within 5hr. of delivery. 4. The results are discussed in relation to the function of adrenal steroids in postnatal liver development.     

Plasma prolactin,progesterone and oestradiol-17β concentrations around parturition in the pig

Plasma concentrations of prolactin, progesterone and oestradiol-17β were measured by radioimmunoassay in samples taken from 2–15 days before until 1–4 days after spontaneous parturition in four sows and in one sow around prostaglandin F2α-induced parturition.Between Days ?15 and ?2 (Day 0 = parturition), prolactin concentrations in daily samples fluctuated somewhat, but exceeded 10 ng/ml only exceptionally. Plasma progesterone levels gradually declined or remained high until about 2 days before parturition. A final decrease of the progesterone concentrations coincided with distinct increases of the prolactin levels during the last 40 h of pregnancy.Maximal prolactin concentrations were measured before the onset of delivery of the piglets. Oestradiol-17β reached peak values around delivery. Prostaglandin F2α injection caused an immediate sharp increase of the prolactin concentration which lasted for about 6 h. During this period progesterone and oestradiol-17β concentrations did not change. A second elevation of prolactin levels was measured when progesterone finally decreased.Changes of prolactin concentrations found in this study were compared with those found in other domestic animals at the same reproductive stage.     

Autoclaved, previously used intravaginal progesterone devices induces estrus and ovulation in anestrous Toggenburg goats

Intravaginal progesterone devices are used worldwide for estrus induction in goats. Reused devices are able to induce estrus; however, this can be a health risk within a flock. The objective was to compare new and previously used (and autoclaved) progesterone-releasing intravaginal devices for induction of estrus and ovulation in seasonally anestrous Toggenburg goats. Anestrous goats (n=42) received new intravaginal devices containing 0.3g progesterone (CONTROL), or similar devices previously used for either 6 (USED6) or 12d (USED12) and subsequently autoclaved. All goats received 5mg dinoprost at device insertion and 200 IU eCG 5d later, and all devices were removed after 6d. After device removal, estrus was monitored and females displaying signs of estrus were mated by fertile bucks. Transrectal ovarian ultrasonography was performed after device removal until detection of ovulation. Blood samples were collected for determination of plasma progesterone concentration at different times. There was no difference (P>0.05) among groups CONTROL, USED6 or USED12 for: estrus response (87, 100 or 100%, respectively); duration of estrus (32.3±2.3, 25.2±3.4 or 27.3±4.1h); ovulation rate (100, 88 or 100%); number of ovulations (1.5±0.2, 1.9±0.3 or 1.7±0.3); and pregnancy rate (60, 58 or 67%). Plasma progesterone (P4) concentrations were greater (P<0.05) in CONTROL than in USED6-treated and USED12-treated goats (7.2±1.2, 4.7±0.7 and 4.3±0.6 ng/mL, respectively) at 6h after device insertion; these differences were maintained until 4d after device insertion (3.4±0.4, 2.3±0.2, and 2.5±0.2 ng/mL). Overall, plasma progesterone concentrations were greater (P<0.05) in nulliparous than in lactating goats (3.1±0.8 compared to 2.4±0.6 ng/mL, respectively). In conclusion, autoclaved, previously used intravaginal progesterone-releasing devices resulted in significant lesser plasma progesterone concentrations than new devices, but were similarly effective in inducing estrus and ovulation in anestrous goats.