New technologies for the study of carnivore reproduction

Routine analysis of urinary metabolites of estrogen and progesterone provided substantial information about the estrous cycle of bears. However, these data alone were not adequate to determine the precise timing of ovulation needed to maximize AI success rates, or to distinguish between pregnancy and pseudopregnancy. Therefore, there is a critical need to develop technologies that will enhance understanding of the reproductive mechanisms of ursids. Using the domestic dog as a model, three techniques were investigated for potential application to the propagation of captive endangered bears. In a modification of standard staining of bitch vaginal cells, trichrome staining of giant panda cells revealed two consistent chromic shifts 9 and 2 days prior to the periovulatory decrease in urinary estrone sulfate, enhancing the ability to predict ovarian events preceding ovulation. To further define the relationship between the decrease in estrogen and ovulation, the utility of a rapid immunochromatographic LH assay was investigated for giant pandas using a commercial LH kit canine serum. Serum collected during estrus exhibited positive test results, indicating the cross-reactivity of giant panda LH with canine LH antibodies, and preliminary data supported further development of the LH kit for the detection of LH in bear urine. Due to the limitations of hormone analysis for distinguishing pregnancy from pseudopregnancy in canids and ursids, forward-looking infrared thermography was evaluated as a method to visualize proliferating placental tissue, fetuses, or both. While further investigation is needed to confirm the utility of thermal imaging for pregnancy diagnosis in the domestic bitch, pregnancy and pseudopregnancy were successfully detected in two giant pandas.     

Long-term data on basic reproductive parameters and evaluation of endocrine,morphological, and behavioral measures for monitoring reproductive status in a group of semifree-ranging Tonkean macaques (Macaca tonkeana)

Cycle and gestation lengths, menstruation patterns, female genital swelling characteristics, and male-female consortship durations are reported in a semifree-ranging group of Tonkean macaques (Macaca tonkeana) studied over a 12 year period. In addition, profiles of urinary estrone conjugates (E1C) and immunoreactive pregnanediol glucuronide (PdG) throughout four complete menstrual cycles in two females and three full-term pregnancies are presented. Based on intermenstrual intervals, a mean cycle length of 37–41 days (n = 55 cycles in 10 females) was found. Gestation length averaged 173 days (n = 27 pregnancies in eight females). Measurement of PdG immunoreactivity in urine revealed a cyclic pattern with a 5–15-fold increase between follicular and luteal phase concentrations, suggesting that PdG is a reliable indicator of ovarian cyclicity and luteal function. In contrast to PdG, E1C excretion showed no clear pattern throughout the cycle; however, highest values of E1C were usually found shortly before the onset of the luteal phase PdG rise at the presumed time of ovulation. Levels of both hormones were elevated during the first half of gestation and showed a marked increase throughout the second half, with maximum E1C concentrations being up to 100-fold higher than nonpregnant levels. Consortships by the male and occurrence of female genital swelling were long lasting (on average 5–10 days and 13 days, respectively) and were restricted to the follicular phase of the cycle. The day of maximal swelling and day of detumescence as well as the end of male consortship were closely associated with the periovulatory period. Swellings and consortships were longer following lactational ammenorhea than for subsequent cycles. The evolutionary significance of the cyclical changes undergone by females upon their relations with males is discussed. © 1996 Wiley-Liss, Inc.     

Assessment of female reproductive status in captive-housed Hanuman langurs (Presbytis entellus) by measurement of urinary and fecal steroid excretion patterns

The study reports on the use of urinary and fecal hormone measurements for monitoring female reproductive status in captive-housed Hanuman langurs (Presbytis entellus). Matched urine and fecal samples collected throughout 7 complete menstrual cycles of two females, and during part of one pregnancy in a third female were analyzed. Estrone conjugates (E1C) and immunoreactive pregnanediol glucuronide (PdG) in urine and immunoreactive estradiol (E2), progesterone (P4), pregnanediol (Pd) and 20α-hydroxyprogesterone (20αOHP) in feces were measured by enzymeimmunoassay. E1C and PdG in urine were excreted in a cyclic pattern with E1C levels increasing 3- to 4-fold during the follicular phase to reach preovulatory peak values 2 days before a defined rise in PdG concentrations. Cycle lengths ranged between 20 and 34 days comprising a variable follicular phase of 7–21 days and a more consistent luteal phase of 12–14 days. High pressure liquid chromatography (HPLC) analysis of fecal extracts confirmed the presence of all fecal hormones measured, but indicated large amounts of additional immunoreactivity in the three progestin assays. The patterns of excretion of fecal E2 and all three fecal progestins corresponded well with those of steroid metabolites in urine in showing a clear and well defined follicular phase E2 rise followed by a luteal phase progestin increase. Measurement of 20αOHP immunoreactivity revealed the most stable baseline and the highest follicular/luteal phase differential. Levels of all hormones were clearly elevated during pregnancy although urinary E1C and PdG showed a more pronounced increase compared to fecal metabolites. The results indicate that urinary and fecal hormone analysis can be applied to noninvasive monitoring of reproductive status in the Hanuman langur. © 1995 Wiley-Liss, Inc.     

Measurement of thymus weight, lumbar node weight and progesterone levels in syngeneically pregnant, allogeneically pregnant, and pseudopregnant mice.

Female CBA mice were mated to fertile CBA males, to vasectomized CBA males, to fertile C57BL males or to vasectomized C57BL males. After allogeneic or syngeneic mating the extent of thymic involution on the 10th day of pregnancy and pseudopregnancy was similar. Lumbar lymph node weight was not affected by pseudopregnancy but increased similarly in allogeneic and syngeneic pregnancies. Serum progesterone levels on the 10th day of pseudopregnancy were similar to those of non-pregnant females, and significantly lower than those of pregnant females. On the 4th to 7th days progesterone levels in pseudopregnant animals were equal to those in pregnant animals. Progesterone levels and thymic involution were similar in syngeneically and allogeneically pregnant females. Progesterone levels were negatively correlated with thymus weight but reached significance only when the mating was allogeneic. It is suggested that there is an interaction between progesterone concentrations and the degree of thymic involution during pregnancy.     

Pregnancy, lactation and the oestrous cycle of the pouched mouse, Saccostomus campestris

The anatomy and histology of pouched mouse ovaries were studied during the oestrous cycle, pregnancy and lactation along with the relationship between the ovarian structures and circulating concentrations of progesterone. The structure of the ovaries resembled that of most rodents. Follicular development indicated that ovulation takes place on the night between pro-oestrus and oestrus, i.e. at the time when mating normally occurs. Corpora lutea were accumulating in cyclic females, while successively disappearing during pregnancy, leaving only the set formed after conception. After parturition luteal regression was rapid. Theca interna, included in the corpora lutea, formed glandular stromal tissue after regression of the luteal tissue formed from granulosa cells. The progesterone profile of non-pregnant females indicated a short but functional luteal phase (peak at metoestrus) during the cycle. During pregnancy three peaks of progesterone stood out: (1) when implantation starts, (2) when older sets of corpora lutea showed rejuvenation and placental signs were found in the vaginal smears, and (3) 3 days before expected parturition when luteal development (as judged by histology) reached a peak. The placenta may participate in but not 'take over' the progesterone production during later stages of pregnancy. Very low concentrations of peripheral progesterone during lactation and a very low level of follicular development at that time support an earlier suggestion of a lactational anoestrus in pouched mice.     

Daily activity of captive giant pandas (Ailuropoda melanoleuca) at the wolong reserve

Daytime activity patterns of captive giant pandas (Ailuropoda melanoleuca) (n = 21) were observed for 2 week periods during October 1991 and January, April, and July 1992. A daytime bimodal activity pattern was seen with increased activity coinciding with feeding times at 1000 and 1600 h. The animals spent an average of 40 ± 10% of their time sleeping, 21 ± 10% resting, 25 ± 11% eating, 13 ± 9% walking, and 1 ± 3% interacting with other giant pandas. Adult females were less active than males or juveniles. During July, giant pandas were less active during the daytime than during other seasons of the year. There was no difference in activity patterns between pregnant and non-pregnant females. Two infants had similar activity patterns to the adults by the time they were 6 months old. Comparison with wild giant pandas (n = 5) at the Wolong Nature Reserve revealed similar bimodal activity cycles, although the time of peak activity differed and foraging/feeding time was greater for wild pandas than for captive animals. © 1994 Wiley-Liss, Inc.     

Pregnancy and early reproductive failure in the baboon

We documented normal pregnancy and the rate of pregnancy failure in female baboons by measuring chorionic gonadotropin (bCG) and progesterone (P) levels in 162 mated cycles of 70 baboon females on days 10, 12, and 14 postovulation. Females were mated with males during turgescene. The presence of pregnancy was defined by bCG levels >20 μg/ml by day 14 postovulation and/or documentation of a gestational sac using ultrasonography. Of the 162 cycles, 75 were fertile. Of these animals, 33 were used in other studies and thus were not included in these analyses. The analyses are based on 43 pregnancies from 91 cycles that were untreated throughout their gestations. Twenty-six of these pregnancies had abnormal bCG and/or progesterone levels in early pregnancy. All of those pregnancies with abnormal endocrine parameters terminated with spontaneous abortion (60%). Certain abnormal bCG patterns were repeatedly observed in some animals and were correlated with repeated spontaneous abortions. Of 17 pregnancies with normal bCG and P patterns, 15 (88%) continued to term with a normal fetal outcome. In this study, a pregnancy rate per mated cycle of 47% was observed, yet 60% of untreated pregnancies abortyed spontaneously. Overall 16% of the mated cycles had continuing pregnancies with normal outcome. These studies demonstrate that a high rate of early abortions occurs in the baboon and that a single bCG determination is insufficient to define the presence of a “normal” pregnancy which might be expected to carry to term with a normal outcome.     

Pregnancy diagnosis in urine of Iberian lynx (Lynx pardinus)

Diagnosis of pregnancies is an important management tool for the Iberian lynx Conservation Breeding Program, a program geared to recover the world's most endangered felid. Non-invasive methods such as fecal hormone analyses are not applicable to the lynx, since fecal progestin does not follow the typical pregnancy pattern of felids. Therefore, we aimed to test whether urine can be used as an alternative substance for pregnancy diagnosis in the Iberian lynx.Progesterone immunoreactive metabolites were determined in urine samples of pregnant and non-pregnant females before and during breeding season. Additionally, we used the Witness^®Relaxin test to determine relaxin in blood and urine. No differences were found in progestin concentrations determined in urine samples collected from pregnant and non-pregnant animals between day 1 and 65 following mating. Although the Witness^®Relaxin test was positive in serum samples collected from animals between day 32 and 56 of pregnancy, it failed in both fresh and frozen urine samples collected from the same stage of pregnancy. A weak relaxin reaction in urine samples collected from animals between day 29 and 46 of pregnancy was detectable after urines were concentrated by ultrafiltration (>50×). Concentrated samples obtained from non-pregnant and early pregnant animals yielded negative test results. In conclusion, the Witness^®Relaxin test can be applied for pregnancy diagnosis in Iberian lynx in both serum and concentrated urine samples obtained during the second half of pregnancy. A positive relaxin test indicates an ongoing pregnancy, whereas negative tests must be judged carefully as hormone concentrations might be below detection thresholds.     

Changes of urinary steroid conjugates and gonadotropin excretion in the menstrual cycle and pregnancy in the Yunnan snub-nosed monkey (Rhinopithecus bieti).

The Yunnan snub-nosed monkey (Rhinopithecus bieti) is one of the most endangered species in the world, and it is endemic to China. According to our knowledge, there was no information on reproduction for this species. The present study was designed to understand the characteristics of reproductive hormone secretion during the menstrual cycle and pregnancy of this species by monitoring urinary estrone conjugate (E1C), pregnanediol-3-glucuronide (PdG), bioactive follicle-stimulating hormone (FSH), and luteinizing hormone (LH). The urine samples were collected each day from four adult females for eight menstrual cycles, and once in 3 days during pregnancy (three full-term pregnancies, one mid-term abortion). The steroid conjugate was tested by radioimmunoassays (RIAs), and bioactive FSH and LH levels were measured in vitro by the sensitive bioassays granulosa cell aromatize bioassay (GAB) and rat interstitial cell testosterone (RICT), respectively. The results showed that: 1) E1C presented a preovulatory peak (183.9 +/- 8.6 ng/mgCr) followed by a definite elevation of PdG; 2) PdG in the luteal phase (754.4 +/- 30.6 ng/mgCr) was three- to fivefold higher than during the corresponding follicular phase (198.3 +/- 11.4 ng/mgCr); 3) the peaks of bio-LH and bio-FSH were on the same day, while the E1C peak was 1 or 2 days before the peaks for these two hormones; 4) bio-FSH levels were higher in the follicular phase than in the luteal phase, and bio-LH levels elevated slightly in the luteal phase; 5) the mean cycle length was 23.6 +/- 3.5 days (n = 3) based upon successive urinary LH peaks; 6) based on the interval from the day of E1C peak to the day of parturition, the gestation was 203.7 +/- 2.5 days (n = 3); and 7) both E1C and PdG increased and remained high after pregnancy, with a sharp decrease in basal levels following parturition or mid-term abortion. The results suggested that the pattern of reproductive hormones for R. bieti is similar to that of other Old World monkeys, but the concentration of the hormones is different from that of other species. This species has a longer progestation period, which may be related to its classification status.     

Endocrine monitoring of the ovarian cycle and pregnancy in the saddle-back tamarin (Saguinus fuscicollis) by measurement of steroid conjugates in urine

Direct measurements of urinary immunoreactive estrone conjugates (E1C) and pregnanediol glucuronide (PdG), were applied to monitoring the ovarian cycle (n = 9) and pregnancy (3 full term pregnancies, 2 mid-term abortions) in Saguinus fuscicollis. During the ovarian cycle, urinary E1C concentrations revealed a high degree of day-to-day variability and appeared to be uninformative in reflecting cyclic ovarian function. In contrast, PdG was a reliable indicator of ovarian cyclicity with excretion patterns corresponding well with plasma progesterone profiles. Luteal phase PdG concentrations were on average 4–7–fold higher than corresponding follicular phase values. On the basis of changes in circulating progesterone, a mean cycle length of 25.7 ±1.0 days with an average follicular phase of 7.1 ± 0.6 days and a mean luteal phase of 18.6 ± 0.7 days, was found (n = 14 cycles). Following conception, both urinary steroid conjugate concentrations increased and elevated levels were maintained beyond the normal luteal phase length, allowing pregnancy to be determined at around day 25–30. During mid- to late pregnancy, PdG levels declined while E1C concentrations continued to be elevated until approximately 6 weeks before parturition when a decrease occurred. Both hormones showed a clear and rapid fall to follicular phase values following termination of pregnancy at either parturition or mid-term abortion. Post partum ovulations (n = 5) occurred on average 17–18 days following birth with four ovulations leading to conceptions. The results demonstrate the potential of urinary steroid conjugate analysis as a practical and reliable method for non-invasive monitoring of reproductive status in the female saddle-back tamarin. © 1995 Wiley-Liss, Inc.     

Fecal progesterone and estrogen metabolite monitoring for cyclicity and pregnancy in southern tamandua (Tamandua tetradactyla)

Reproductive management of the southern tamandua (Tamandua tetradactyla) should include timed introductions for breeding to minimize aggression and pregnancy monitoring. Since serial blood sampling could cause unnecessary stress, and urinary progesterone metabolites are found in very low concentrations, this study sought to validate progesterone and estradiol enzyme immunoassays for measuring fecal progesterone metabolite (FPM) and fecal estrogen metabolite (FEM) concentrations in two females. Peaks in FEM concentrations coincided with breeding and conception, were 5–6 times higher than baseline concentrations, and were followed by clear luteal phases distinguished by FPM concentrations 5–6 times higher than baseline concentrations. FPM concentrations during the first 30–53 days of gestation overlapped with luteal phase concentrations, thereafter increasing to 8–25 times higher than baseline concentrations. FEM concentrations during the first 41–44 days of gestation remained near basal values for one female, whereas concentrations were 1.8 times higher than baseline for the second. FEM concentrations became elevated for the former by 44 days of gestation and increased further for the latter after 53 days, ultimately averaging four times higher than baseline for both females. The biphasic increase in FPM and FEM concentrations, follicular and luteal phase durations (follicular: 7 ± 1 days, luteal: 25 ± 1 days), total cycle length (41 ± 1 days), and gestation (161–165 days) documented in this study were consistent with previous reports from serum and urine analyses. Monitoring FPM and FEM is a reliable noninvasive method for tracking reproductive cycles and pregnancy in southern tamandua that overcomes the challenges associated with serum or urinary hormone analysis.     

Pregnancy in female house mice exposed to urinary chemosignals from other females.

Seven experiments were performed to investigate pregnancy termination, urinary chemosignals, and litter sex ratio variation in female house mice. Experiments tested the effects of urine from adult and prepubertal females, housed individually or in groups, on successful insemination and litter production by females treated at different times and for different periods during the 3 weeks before mating and during gestation. Treatment of females with urine from adult females housed eight per cage or with urine pooled from eight adult females housed individually for 2 or 3 weeks before mating resulted in fewer successful pregnancies and significantly more female-biased litters. Treatment with urine from adult or prepubertal females housed eight per cage or with urine pooled from eight mice housed individually for the first 6 days of gestation or throughout pregnancy resulted in a significant increase in the rate of pregnancy termination. These treatments resulted in lower body weights at birth and slower growth rates in all males and in some females. Puberty was delayed in female progeny from urine-treated dams in five of seven experiments, and these young females attained first oestrus at greater mean body weights than mice in other treatments. These findings indicate that, in mice, at high population density, communication via a urinary chemosignal can alter reproduction in recipient females. Availability of, and competition for, resources such as food would be greater at higher densities, possibly lowering the probability of reproductive success. Pregnancy termination and delays in reproduction and attainment of sexual maturity might lead to greater successful reproduction at a later time.     

Assessment of ovarian function in the African elephant (Loxodonta africana) by measurement of 5α-reduced progesterone metabolites in serum and urine

We have previously shown that 5α-pregnane-3,20-dione (5αDHP), and 5α-pregnane-3-ol-20-one (5α-P-3-OH) are the major luteal and circulating progestins in the African elephant. Therefore, the aim of the present study was to determine (1) circulating levels and patterns of secretion of 5α-DHP in relation to progesterone (P4) throughout the ovarian cycle, (2) the presence and relative abundance of 5α-reduced progestins in urine and (3) whether their measurement in urine would provide a non-invasive method for monitoring luteal function. Urine samples were collected weekly throughout a total of 13 ovarian cycles from 5 females. In addition, matched blood samples were collected during 6 cycles from 2 of the 5 animals. All hormone measurement, were carried out by enzymeimmunoassay following extraction. Urine was hydrolyzed prior to extraction. Profiles of P4 and 5α-DHP in serum followed a similar cyclic pattern and both measurements were significantly correlated (r = 0.78–0.98, mean 0.89, P < 0.001). Concentrations of 5α-DHP were, however, 10–20 fold higher than those of P4. I addition, 5α-DHP measurements showed a more pronounced luteal phase increase than that of immunoreactive P4. HPLC co-chromatography confirmed the presence of large amounts of 5α-P-3-OH in urine as a single immunoreactive peak, whereas 5α-DHP was present in very low levels and measurable only as one of several immunoreactive substances. Measurements of urinary 5α-P-3-OH were significantly correlated to serum 5α-DHP measurements in each of the 6 cycles (r = 0.72–0.93, mean 0.81, P < 0.001), whereas correlation coefficients between urinary and serum 5α-DHP values were generally lower (r = 0.34–0.83, mean 0.69) and significant in only 4 of the 6 cycles. Accordingly, only urinary excretion of 5α-P-3-OH, but not of 0.15–0.20 μ/mg Cr in the follicular phase and 10-fold elevated levels (1.8–2.2 μg/mg Cr) in the luteal phase. Based on the intervals between successive luteal phase increases in urinary 5α-P-3-OH, a mean cycle length of 14.1 ± 1.8 weeks, comprising a follicular phase of 5.0 ± 0.9 weeks and a luteal phase of 9.1 ± 1.4 weeks was determined for the 13 cycles studied. The results indicate that measurements of 5α-P-3-OH in urine provide a reliable non-invasive method for monitoring luteal function in the African elephant. Zoo Biol 16:273–284, 1997. © 1997 Wiley-Liss, Inc.     

Urinary progesterone in free-ranging red howler monkeys (Alouatta seniculus): preliminary observations of the estrous cycle and gestation

The goals of this study were to develop and validate a radioimmunoassay (RIA) for measurement of unconjugated progesterone (P) concentrations in the urine of red howler monkeys (Alouatta seniculus) and to use urinary P profiles to characterize the reproductive cycle of this species. Analysis of P profiles from two females provided a preliminary estimate of the length of the estrous cycle (mean days +/- S.E.M. = 29.5 +/- 1.5; n = 2), and indicated that one female red howler copulated throughout two apparent estrous cycles. Urinary P concentrations during two confirmed pregnancies (211.8 +/- 29.7 ng P/ml) were higher (P < 0.05) than during the luteal phase (77.4 +/- 10.6 ng P/ml; n = 4) of the cycle.     

Simultaneous choice bioassays accompanied by physiological changes identify civetone and decanoic acid as pheromone candidates for giant pandas

Chemicals present in urine are thought to play an important role in mate identification in the solitary giant panda (Ailuropoda melanoleuca). During the breeding season, females will deposit chemical signals to advertise sexual receptivity to potential mates. The goal of this study was to determine if specific volatile compounds found in female urine could be considered as pheromones that elicit behavioral and physiological responses in males. Experimental simultaneous choice trials were conducted with captive male giant pandas (n = 3) housed at Memphis Zoo, San Diego Zoo, and Zoo Atlanta. Octanoic acid, 1H-pyrrole-2-carboxaldehyde, decanoic acid, and civetone were selected as stimuli because previous studies reported their elevation in urine during the breeding season. Male interest was determined by a behavioral preference toward these volatile compounds diluted in synthetic urine compared with nontreated synthetic urine. Male urine samples were collected 1 week prior, during, and 1 week after the experimental period to assess changes in urinary semiochemical composition and urinary androgen concentrations. No significant differences in investigation response (p = .395) or flehmen response (p = .600) were found when stimuli were compared; however, decanoic acid and civetone elicited a behavioral preference over the control (response ratio > 0.5). The relative abundance of 16 compounds identified in male urine was significantly elevated (p < .05) above baseline values after the males were exposed to the stimuli. Androgen levels were significantly elevated (p < .05) in one male after exposure to 1H-pyrrole-2-carboxaldehyde, decanoic acid, and civetone. These data suggested that civetone and decanoic acid in female urine may motivate sexual responses in males.     

Reproductive monitoring of free-ranging female mountain gorillas by urinary hormone analysis

Frequent urine samples from three habituated free-ranging adult female mountain gorillas were collected during a four-week period in order to characterize, by analysis of urinary hormones, their ovarian cycle, and to diagnose pregnancy. A conceptive cycle and two cycles that did not result in full term pregnancy were monitored. Behavioral and physiological observations of mating and labial swellings were correlated to urinary hormone results. Mating occurred on days with elevated estrogens. Labial swelling was maximum near or at peak estrogen levels. Pregnancy was diagnosed at the field site by measurement of chorionic gonadotropin using commercially available human pregnancy detection kits. In one pregnancy, gestation length was 254 days. The pregnanediol glucuronide concentrations of the mountain gorilla did not change during the nonconceptive cycle. During the conceptive cycle, the concentrations did not increase until the approximate time of implantation. This finding suggests marked differences in steroid production or metabolism between the mountain gorilla and the captive lowland gorilla.     

Social suppression of ovarian cyclicity in captive and wild colonies of naked mole-rats, Heterocephalus glaber

To investigate the endocrine cause of reproductive suppression in nonbreeding female naked mole-rats, animals from 35 colonies were studied in captivity. Urinary and plasma progesterone concentrations were elevated in pregnant females (urine: 10.0-148.4 ng/mg Cr, 27 samples from 8 females; plasma: 3.6-30.0 ng/ml, 5 samples from 5 females; Days 21-40 of pregnancy) and cyclic breeding females (urine: 0.5-97.8 ng/mg Cr, 146 samples from 7 females; plasma: less than 1.0-35.4 ng/ml, 25 samples from 7 females). The latter group showed cyclic patterns of urinary progesterone, indicating a mean ovarian cycle length of 34.4 +/- 1.6 days (mean +/- s.e.m.) with a follicular phase of 6.0 +/- 0.6 days and a luteal phase of 27.5 +/- 1.3 days (19 cycles from 9 breeding females). In non-breeding females urinary and plasma progesterone values were undetectable (urine: less than 0.5 ng/mg Cr, 232 samples from 64 females; plasma: less than 1.0 ng/ml, 7 samples from 6 females). Breeding females had higher (P less than 0.001) plasma LH concentrations (3.0 +/- 0.2 mi.u./ml, 73 samples from 24 females) than did non-breeding females (1.6 +/- 0.1 mi.u./ml, 57 samples from 44 females). Urinary and plasma progesterone concentrations in non-breeding females from wild colonies situated near Mtito Andei, Kenya, were either below the assay sensitivity limit (urine: less than 0.5 ng/mg Cr, 11 females from 2 colonies; plasma: less than 1.0 ng/ml, 25 females from 4 colonies), or very low (plasma: 1.6 +/- 0.6 ng/ml, 15 females from 4 colonies). In captivity, non-breeding females removed from their colonies (i.e. the dominant breeding female) and either paired directly with a non-breeding male (N = 2), or removed and housed singly for 6 weeks before pairing with a non-breeding male (N = 5) may develop a perforate vagina for the first time in as little as 7 days. Urinary progesterone concentrations rose above 2.0 ng/mg Cr (indicative of a luteal phase) for the first time 8.0 +/- 1.9 days after being separated. These results suggest that ovulation is suppressed in subordinate non-breeding female naked mole-rats in captive and wild colonies, and show that plasma LH concentrations are significantly lower in these non-breeding females. This reproductive block in non-breeding females is readily reversible if the social factors suppressing reproduction are removed.     

Melengestrol acetate implant contraception in addax (Addax Nasomaculatus) and Arabian oryx (Oryx Leucoryx)

Melengestrol acetate (MGA) implants were used for contraception in three addax and three Arabian oryx females housed at the Saint Louis Zoo. Serum estradiol and progesterone or fecal estrogen and progestin analysis and ultrasonography of reproductive tracts were used for monitoring changes before, during, and after MGA treatment. Follicular development and irregular uterine fluid accumulation were detected in all females during MGA treatment. Although housed with an intact male for all or most of the contraceptive period, no pregnancies occurred. One female addax may have ovulated, based on sustained elevated progesterone levels, and another showed continued follicle development, as seen by fluctuating estradiol concentrations. Reversibility was documented in two of the three addax that resumed reproductive cycles post‐MGA‐implant removal, whereas the third, a peripubertal female, did not cycle before, during, or after treatment. Addax females were lost to further follow‐up after transfer to another institution, so the possibility of subsequent pregnancies is not known. All three Arabian oryx ovulated during the initial MGA treatment, but two of the three females had implants past the typical 2‐year efficacy period. They had regular ovulatory cycles after implant removal, with mean cycle length of 27.5±1.5 days and mean luteal phase duration of 15.2±0.7 days. Reversibility was further shown in all three oryx by pregnancies after placement with a male approximately 2 years after MGA implant removal. Two produced healthy calves, but the third died owing to an unrelated terminal illness in the mother. Zoo Biol 26:299–310, 2007. © 2007 Wiley‐Liss, Inc.     

Progesterone, but not luteal estrogen, is required for the establishment of pregnancy in the new world monkey Cebus apella

The aim of this study was to examine the requirement of luteal progesterone or luteal estrogen for the establishment of pregnancy in the Cebus monkey and to test in a primate species the synergism between RU 486 and letrozole (LTZ) found in rodents for inhibiting implantation. Exposure of target tissues to either hormone was suppressed during the mid-luteal phase of mating cycles by subcutaneous administration of the antiprogestin (RU 486), the aromatase inhibitor LTZ or the antiestrogen (ICI 182780) on days 4-7 of the luteal phase. Administration of 0.1 or 0.5 mg/kg of LTZ on days 5-7 of the luteal phase caused a profound drop in the levels of E(2) in all animals, whereas administration of ICI 182780 0.2 mg/kg on days 4-6 of the luteal phase had the opposite effect. The pregnancy rate in vehicle treated cycles of the same females was (58.3%). Treatment with RU 486, 0.8 mg/kg/day on days 5-7 of the luteal phase-induced endometrial bleeding in 3/5 mated females none of which became pregnant, whereas pregnancy was confirmed in one of the two animals that did not bled. Treatment with RU 486, 0.4 mg/kg/day alone or with LTZ on days 5-7 or ICI 182780 alone, on days 4-6 of the luteal phase failed to induce bleeding, allowing the establishment of pregnancy in 50.0-66.6% of the animals in these groups. We conclude that in Cebus monkeys, progesterone but not luteal estradiol is required for the establishment of pregnancy and that RU 486 and LTZ do not exhibit in this species the synergism found in rodents.     

Pregnancy rate in timed-mated, spontaneously cyclic rhesus monkeys, Macaca mulatta

After detection of the preovulatory oestradiol-17 beta peak in blood, females were placed with a male and left undisturbed during mating (N = 28, 94 cycles) or were exposed to serial diagnostic laparoscopy (1-4 occasions) to monitor ovulation (N = 87, 224 cycles). A total of 86 pregnancies resulted from timed mating in the 318 menstrual cycles (27% rate). When periovulatory laparoscopy was performed, the pregnancy rate was 22.3%. In the absence of laparoscopy the pregnancy rate was 38.3% (P less than 0.003). These pregnancy rates are similar to those of women and show an adverse effect of laparoscopy on pregnancy rate.