Progesterone concentration in the peripheral plasma of pregnant goats

Variations, validations, degradations, and noninvasive determination of pregnancy using fecal steroid metabolites in free-ranging pronghorn

Pregnancy status is a key parameter used to assess reproductive performance of a species as it represents a starting point for measuring vital rates. Vital rates allow managers to determine trends in populations such as neonate survival and recruitment; two important factors in ungulate population growth rates. Techniques to determine pregnancy have generally involved capture and restraint of the animal to obtain blood samples for determining serum hormone levels. Non-invasive pregnancy assessment, via feces, eliminates any hazards between handler and animal, as well as removes handling-induced physiological biases. Using noninvasive fecal sampling, we conducted hormone validations, investigated pregnancy rates, and determined hormone degradation rates across five subpopulations of pronghorn (Antilocapra americana) in Idaho. Samples were collected during April-May of 2018 and 2019 from adult pronghorn of known sex and age class. Metabolites of testosterone, cortisol, 17β-estradiol, and progesterone were measured in fecal samples, and concentrations of estradiol and progesterone were examined for pregnancy determination. Average fecal progesterone metabolite (FPM) levels of pregnant females were more than double compared to levels of nonpregnant females. Fecal estrogen metabolite (FEM) levels did not differ during concurrent sampling. The largest difference in FPM levels between pregnant and nonpregnant females began on 28 April. Pregnancy determination sampling showed average FPM levels for all five subpopulations were significantly different than the nonpregnant female validation group. Nonetheless, pregnancy rates for some subpopulations lacked conclusive estimates due to early fecal sampling. Fecal glucocorticoid metabolites (FGM) levels significantly differed between pregnant females and male pronghorn, but did not differ from nonpregnant females. Degradation rates of FPM and FGM differed across days, with values for FPM from Day 1 being significantly different from all subsequent days, and after Day 9 for FGM, demonstrating the requirement of fresh samples to accurately measure hormone concentrations. We concluded that a noninvasive method to diagnosis pregnancy is possible in pronghorn via progesterone metabolites if fresh samples are collected during late gestation.

Temporal changes in pregnancy-associated glycoproteins across different stages of gestation in the Barbari goat

The objective of this study was to characterize the temporal profile of pregnancy-associated glycoproteins (PAGs; isoforms 1-11) across different stages of gestation in the Barbari goat. Placentae were collected from local abattoir, classified according to crown rump length of the corresponding foetus into five groups (0-30, 31-60, 61-90, 91-120, and 121-150 days of gestation), and used for relative quantification of mRNA expression by Pfaffl method. In addition, adult female goats (pregnant, n = 7; non-pregnant, n = 5) were used to estimate weekly plasma PAG and progesterone (P4) concentrations. The relative mRNA expression of PAGs was greater (p<0.05) during 31-60 days of gestation, which correlated well with the temporal changes in plasma PAG concentrations. Relative expression of PAGs decreased steadily as gestation advanced with minimum expression observed just before parturition, except for PAG-4 and PAG-8 that showed constantly higher expression throughout pregnancy. Plasma PAG and P4 concentrations showed a distinct temporal pattern with a significant increase beginning at 2 weeks and return to basal levels by 20 weeks of gestation. However, PAG concentrations reached a peak earlier in gestation (8 weeks) than P4 (10-14 weeks). Correlation analysis indicated a strong positive association (r = 0.748, p<0.01) between plasma PAG and P4 concentrations. In conclusion, results of this study indicate a distinct temporal pattern of PAG expression and secretion during gestation in the Barbari goat. The temporal changes in PAGs and the positive association with P4 are suggestive of their role in maintenance of pregnancy and progressive foetal development.

Molecular Cloning of Goat 20.ALPHA.-Hydroxysteroid Dehydrogenase cDNA

20Alpha-hydroxysteroid dehydrogenase (20alpha-HSD), which catalyzes the conversion of progesterone to its inactive form 20alpha-dihydroprogesterone, is expressed in murine placenta and has been suggested to play roles in maintaining pregnancy. To understand the role of 20alpha-HSD during pregnancy in the goat, as a first step, cloning and sequencing of 20alpha-HSD cDNA were performed. The full nucleotide sequence of 20alpha-HSD cDNA was determined on samples obtained from the corpus luteum at the luteal phase of the estrous cycle and the placenta in late pregnancy by RT-PCR and 3' and 5' RACE systems. Cloned 20alpha-HSD cDNA consisted of 1124 bp and belonged to the aldo-keto reductase superfamily. From the start codon to stop codon there were 323 amino acids, the same as in other species. To verify whether the protein derived from goat 20alpha-HSD cDNA had 20alpha-HSD activity, the cDNA was expressed by bacteria. Bacterially expressed goat 20alpha-HSD protein showed 20alpha-HSD enzyme activity. A tissue distribution study demonstrated that 20alpha-HSD was expressed in the placenta, but not in the adrenal gland, liver and spleen during pregnancy. The present study suggests that goat 20alpha-HSD is another member of the aldo-keto reductase superfamily and that it plays a role in the placenta during pregnancy.

Hormone profile of crossbred goats during the periparturient period

The plasma hormone profile of progesterone, 17 beta-oestradiol, prolactin, growth hormone (GH), cortisol, triiodothyronine (T3), thyroxine (T4) and insulin were estimated by radioimmunoassay in jugular blood samples from 10 Alpine x Beetal crossbred goats during the periparturient period. The plasma progesterone concentrations declined from day 20 prior to kidding to the day of kidding and then remained at a basal level. 17 beta-Oestradiol concentrations declined from day 20 to day 4 prepartum, followed by a continuous increase to reach a peak at kidding. Plasma oestradiol declined abruptly on day 1 postpartum and remained low throughout the postpartum period. The plasma prolactin concentrations increased continuously from day 20 to day 10 prepartum but then increased to a peak on the day of kidding, followed by a transient decline by day 5 postpartum. The plasma GH concentrations varied significantly (p < 0.01) on the different days of sampling but were highest on the day of kidding. The plasma cortisol concentration declined from day 20 to day 2 prepartum, after which it abruptly increased on day 1 prepartum to reach a peak on the day of kidding. The concentrations of plasma T3 remained similar during the prepartum period but were minimal on the day of kidding and increased during the postpartum period. The concentration of plasma T4 was also lowest on the day of kidding and increased during the postpartum period. Plasma insulin concentrations were low in the day of kidding.

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.

Effect of experimental infection with Listeria monocytogenes on the development of pregnancy and on concentrations of progesterone, oestrone sulphate and 15-ketodihydro-PGF2 alpha in the goat

The effect of Listeria monocytogenes infection on hormone levels in pregnant goats was studied. Four goats (Group I) received an intravenous inoculation of a bacterial culture (Type 1) on Days 69-77 and another four goats (Group II) received a similar inoculation on Days 105-106 of gestation. Five non-inoculated goats were used as controls. Plasma was analysed for progesterone, oestrone sulphate and 15-ketodihydro-PGF2 alpha. The status of the foetus was followed using real-time ultrasonography. Three of the four goats in Group I aborted 8-10 days after inoculation. The fourth goat gave birth to a normal live kid at term. The three goats which aborted showed clinical signs of disease in connection with abortion. In Group II, all goats aborted after 9-11 days. All the goats showed clinical symptoms of disease from a few days after inoculation and the symptoms continued until abortion. The clinical symptoms of disease were more pronounced in Group II than in Group I. L. monocytogenes was isolated from all aborted foetuses. None of the control goats aborted. Ultrasound examination revealed foetal death either immediately before or up to 2 days before abortion. Mummification had begun in the foetus that had been dead for 2 days before expulsion. In comparison with pre-inoculation plasma levels in Group I, a significant decrease (P < 0.05) in progesterone levels and an increase in 15-ketodihydro-PGF2 alpha levels were observed from Days 4 and 6 after inoculation, respectively. In Group II, a significant decrease (P < 0.05) in progesterone levels and an increase in 15-ketodihydro-PGF2 alpha levels in plasma were observed from Days 8 and 6, respectively. The oestrone sulphate levels decreased slightly in the inoculated goats a few days before abortion. The pattern of changes in levels around abortion was similar to the pattern present in the control animals around parturition. However, oestrone sulphate levels did not increase in the inoculated groups before abortion in contrast to goats which delivered healthy kids. The changes in levels of 15-ketodihydro-PGF2 alpha in goats that aborted indicated that the endocrine foetal-placental function was disturbed, which was most likely due to the establishment and development of L. monocytogenes in the placenta and foetus.

Effect of Toxoplasma gondii infection on the development of pregnancy and on endocrine foetal-placental function in the goat

The effect of Toxoplasma gondii inoculation on pregnancy and on endocrine foetal-placental function in pregnant goats was studied. Five susceptible goats were inoculated subcutaneously with T. gondii bradyzoites at 71 +/- 2 days of gestation. Another five goats were used as controls. Plasma was analysed for progesterone, oestrone sulphate and 15-ketodihydro-PGF2 alpha. The condition of the foetuses was monitored by real-time ultrasonography. All inoculated goats aborted or delivered stillborn or weak kids 54-73 days after inoculation. None of the goats showed signs of general disease. In cases of foetal death, the ultrasound examination revealed that death occurred between day 1 and 12 before abortion or birth. The appearance of the foetuses varied from fresh to mummified, depending on the number of days between foetal death and expulsion. All five goats became serologically positive to T. gondii after inoculation. None of the goats used as controls aborted, but one goat delivered one mummified and one weak kid for unknown reasons. In inoculated animals an increase in 15-ketodihydro-PGF2 alpha levels in plasma and a subsequent tendency to a decrease in oestrone sulphate levels were observed from about day 40 after inoculation and until abortion or birth. High levels of 15-ketodihydro-PGF2 alpha were seen after foetal death. High levels of 15-ketodihydro-PGF2 alpha were not always followed by a drop in progesterone levels. The mean level of progesterone was slightly decreased after inoculation and onwards. The pattern of progesterone levels around abortion in the inoculated goats was very similar to the pattern around parturition in the control goats. However, 15-ketodihydro-PGF2 alpha levels were higher both before and after abortion in inoculated goats than in control goats. The level of oestrone sulphate did not increase in the inoculated group before abortion in contrast to the level in goats which delivered healthy kids. The patterns of changes in levels of 15-ketodihydro-PGF2 alpha and oestrone sulphate in inoculated animals indicate that the endocrine foetal-placental function was disturbed in most of the inoculated goats, probably due to the injury caused by the establishment and development of T. gondii infection in the placenta and foetus.

Estrous behavior, progesterone in peripheral plasma and milk in dairy goats at onset of breeding season

Two large flocks of 60 and 120 French Alpine dairy does were studied beginning in late June. Estrous behavior was checked daily in the presence of bucks, and numerous blood and milk samples were collected. The end of the anestrus was characterized by consistent low progesterone around .1 ng/ml in plasma and 2 to 4 ng/ml in milk. Cyclic activity was detected in early July in one flock and in early August in the other. Individual patterns of plasma and milk progesterone in cyclic females were correlated greater than .5. Estrus was short (4 to 5 days) in 3 to 10 goats sampled daily following first estrus, and a small and transient rise of concentrations of progesterone was concomitant. Mean plasma and milk progesterone increased from about .1 to .5 and 2 to 4 ng/ml at the time of estrus to 6 to 8 in plasma and 6 to 10 ng/ml in milk 10 days later (midluteal phase). Twenty-one days after mating, concentrations in plasma and milk of pregnant animals were of the same magnitude as during the midluteal phase and higher than those in nonpregnant does (.1 to .7 and 2 to 3 ng/ml in plasma and milk).

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.