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.     

Serum progesterone concentration in pyometritic and normal postpartum dairy cows

Two studies were conducted to evaluate the concentration of serum progesterone in pyometritic cows and relate it to palpation of ovarian structures per rectum . In Trial 1, serum samples from 34 pyometritic cows were assayed for progesterone. Mean serum progesterone concentrations were 6.8 +/- 0.7 ng/ml. In Trial 2, each of 54 pyometritic cows was paired with a control cow on the basis of days post partum (18-50 days). Mean concentration of progesterone was 9.7 +/- 1.0 ng/ml for the pyometritic cows and 5.7 +/- 0.8 ng/ml in control cows (P<0.005). Progesterone concentration was greater (P<0.005) in both groups of cows with palpable corpora lutea (CLs). Ninety-six percent of the pyometritic cows had palpable CLs compared to 57% of the control group. Comparing serum progesterone only in cows with a palpable CL, the mean concentration was still greater (P<0.005) in the pyometritic group (10.6 +/- 1.0 ng/ml) than the control group (6.6 +/- 1.0 ng/ml). Compatability of rectal palpation findings and concentrations of serum progesterone were 92.6% for the pyometritic group and 72.2% for the control group. Progesterone concentration increased (P<0.05) by increased days post partum in Trial 2 (n=54) but not in Trial 1 (n=23). In both Trials 1 and 2, uterine size due to pyometra increased (P<0.05) with increased days post partum. No other associations were found.     

Progesterone and testosterone concentrations during oestrous cycle and pregnancy in the common vole (Microtus arvalis Pallas)

Serum progesterone and testosterone concentrations were measured during different stages of oestrous and pregnancy in paired and unpaired female common voles (Microtus arvalis). Hormone concentrations were measured by ELISA, and cycle stages were determined by vaginal smears. Paired females usually had serum progesterone concentrations of more than 10 ng/ml in the oestrous cycle. A significant maximum was detected in prooestrous (51.70 +/- 7.84 ng/ml, mean +/- S.D.). Serum progesterone concentrations increased from about 40 ng/ml at the beginning of pregnancy to about 70 ng/ml on days 15 and 16. The last 2 days before parturition (days 19 and 20) were characterised by a decrease of progesterone concentrations to ca. 30 ng/ml. The maximum concentration of testosterone was found in prooestrous (1.58 +/- 0.31 ng/ml). Concentrations during pregnancy varied between 1.5 and 2.1 ng/ml. In two of three cases unpaired females exhibited progesterone values below 10 ng/ml, but with varying vaginal smear patterns. The combination of progesterone concentrations and vaginal smear patterns was found to be regular in only 23.8% of the cases. The most frequent cycle stage found was the oestrous (44.2%). Mean concentrations of progesterone (10.43 +/- 13.81 ng/ml) and testosterone (0.85 +/- 1.11 ng/ml) in unpaired females were significantly lower than in paired females, thereby denoting reproductive inactivity in the former. The study presents basic data for several parameters of the reproductive biology in the common vole and confirms the importance of combining hormone assays and vaginal smear monitoring in reproductive research.     

Induction of luteal activity and progesterone secretion in the nonpregnant one-humped camel (Camelus dromedarius)

Corpora lutea (n = 20) were detected in 5 one-humped female camels studied during a period of 4 months. Complete mating by a vasectomized male, male introduction into the pen of females without mating, or a progesterone decrease from a previous corpus luteum were followed by a similar progesterone pattern. A maximal plasma concentration of 4.5 +/- 1.5 ng progesterone/ml (2.7-8.8 ng/ml) occurred 8.55 +/- 1.32 days (6-11 days) after the inducing stimulus. Luteal regression, beginning 8.65 +/- 1.18 days after the stimulus, was completed at Day 11.55 +/- 1.05. Morphological development of ovarian structures, detected by rectal palpation, was in synchrony with the progesterone increase, but there was a prolonged period of regression. Females accepted mating up to 7 days after the ovulatory stimulus, when progesterone levels were as high as 3.5 ng/ml. This study establishes the absence of pseudopregnancy in the one-humped female camel, and offers opportunities for improving the management of reproduction. It also shows that ovulatory stimuli other than mating can be effective in these animals.     

Serum progesterone changes in luteal cyclicity and duration of estrous cycle in Formosan sika deer (Cervus nippon taiouanus) hinds

A study was conducted to investigate the serum progesterone (SP(4)) profiles and duration of estrous cycles in the farmed Formosan sika deer (FSD; Cervus nippon taiouanus) during the major breeding season. Five parous, open and non-milking hinds were allotted to collect peripheral blood samples twice weekly for P(4) measurement by radioimmunoassay beginning at the initiation of the rutting season indicated by rutting behaviors of the sexually mature stags. The hinds were polyestrous as proved by cyclic changes of SP4 levels. After the presumptive estrus shown by the lowest concentration of SP(4) (0.20+/-0.01 ng/ml), this ovarian hormone markedly elevated on day 7 of the cycle (1.67+/-0.11 ng/ml), reached plateau (3.15+/-0.16 ng/ml, P<0.01) during days 11 to 18, and then declined to the basal levels in the subsequent estrus. It is concluded that mean duration of the estrous cycle in FSD during the major rutting season is 19.3 days with a range of 17 to 21 days, and that the patterns of circulating progesterone profiles during the estrous cycles of the FSD are similar to those of other deer species so far investigated.     

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.     

Effects of a gonadotrophin-releasing hormone antagonist on gonadotrophin secretion and gonadal development in neonatal pigs

Male (N = 8) and female (N = 8) pigs were assigned to receive saline or a potent GnRH antagonist ([Ac-D2Nal1,D4-Cl-Phe2,D-Trp3,D-Arg6, D-Ala10]- GnRH*HOAc; 1 mg/kg body weight) at 14 days of age. The GnRH antagonist caused LH to decline (P less than 0.01) from 1.7 ng/ml at 0 h to less than 0.5 ng/ml during 4-32 h in males and females. Concentrations of FSH in gilts declined slowly from 75 +/- 8 to 56 +/- 5 ng/ml (P less than 0.05) at 32 h. In males FSH was low (5.7 +/- 0.5 ng/ml) at 0 h and did not change significantly. To observe the effect of long-term treatment with GnRH antagonist, 10 male and 10 female pigs, 3 days of age, were treated with saline or 1 mg GnRH antagonist per kg body weight every 36 h for 21 days. Concentrations of LH were reduced (P less than 0.01) to 0.2-0.4 ng/ml throughout the experimental period in male and female piglets treated with GnRH antagonist. Plasma FSH increased in control females, but remained suppressed (P less than 0.001) in females treated with GnRH antagonist. Treatment with the GnRH antagonist suppressed FSH levels in males on Days 8 and 16 (P less than 0.05), but not on Day 24. Treatment of females with the GnRH antagonist did not influence (P greater than 0.10) oestradiol-17 beta concentrations. Administration of GnRH antagonist to males suppressed testosterone and oestradiol-17 beta values (P less than 0.01) and reduced testicular weight (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Immunoreactive luteinizing hormone, estradiol, progesterone, testosterone, and androstenedione levels during the breeding season and anestrus in Siberian tigers

Seasonal analysis of 1239 captive births of Siberian tigers (Panthera tigris altaica) indicated a peak in April to June (P less than 0.001). Studies on seven animals in Minnesota indicated that behavioral heat cycles and ovarian follicular phase cycles began in late January and ceased in early June. Behavioral observation of 12 heat cycles in four tigers yielded an estrous length of 5.3 +/- 0.2 days and an interestrous interval of 25.0 +/- 1.3 days. Hormone assays on weekly blood samples (N = 180) from three female tigers indicated 16 cycles in two breeding seasons. Peak estradiol-17 beta levels were 46.7 +/- 6.0 pg/ml (N = 17) and interestrous concentrations were 8.7 +/- 0.66 pg/ml (N = 28) during the breeding season. Anestrous estradiol levels were 4.2 +/- 0.5 pg/ml (N = 70). The interestrous interval between estradiol peaks was 24.9 +/- 1.3 days (N = 9) with two outliers of 42 days. Serum progesterone concentrations from February to June were 1.2 +/- 0.15 ng/ml (N = 32), providing no evidence for ovulation or corpus luteum formation. Luteinizing hormone (LH) levels were 0.56 +/- 0.04 ng/ml (N = 180). Serum testosterone (r=0.71, P less than 0.001) and androstenedione levels (r=0.75, P less than 0.001) were correlated with estradiol during the breeding season. The duration of anestrus was 8 mo in two of these tigers. The interval was shortened in one tiger by exposure to a 16L:8D photoperiod. The Siberian tiger appears to be a polyestrous seasonal breeder and an induced ovulator whose breeding season may be synchronized by photoperiod.     

Oestrous cycles and the breeding season of the Père David's deer hind (Elaphurus davidianus)

Reproductive cycles were studied in a group of tame Père David's deer hinds. The non-pregnant hind is seasonally polyoestrous and, in animals studied over 2 years, the breeding season began in early August (2 August +/- 3.3 days; s.e.m., N = 9) and ended in mid-December (18 December +/- 5.7 days; N = 8) and early January (6 January +/- 3.2 days; N = 11) in consecutive years. During the anoestrous period, plasma progesterone concentrations were low (0.2 +/- 0.01 ng/ml) or non-detectable. There was a small, transient increase in progesterone values before the onset of the first cycle of the breeding season. In daily samples taken during an oestrous cycle in which hinds were mated by a marked vasectomized stag, progesterone concentrations remained low (less than 0.5 ng/ml) for a period of about 6 days around the time of oestrus, showed a significant increase above oestrous levels by Day 4 (Day 0 = day of oestrus) and then continued to increase for 18 +/- 2.8 days to reach mean maximum luteal levels of 3.5 +/- 0.6 ng/ml. The plasma progesterone profiles from a number of animals indicated that marking of the hinds by the vasectomized stag did not occur at each ovulation during the breeding season and therefore an estimate of the cycle length could not be determined by this method. In the following year, detection of oestrus in 5 hinds was based on behavioural observations made in the absence of the stag. A total of 19 oestrous cycles with a mean length of 19.5 +/- 0.6 days was observed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reproductive responses following royal jelly treatment administered orally or intramuscularly into progesterone-treated Awassi ewes

An experiment was conducted to determine whether natural royal jelly (RJ) paste administered orally or intramuscularly (i.m.) in conjunction with exogenous progesterone is associated with improved reproductive responses in ewes. Thirty 3-6-year-old Awassi ewes were randomly allocated into three (RJ-capsule, RJC; RJ-injection, RJI and control, CON) groups of 10 ewes each. All ewes were treated with intravaginal progesterone sponges for 12 days. Ewes in the RJC and RJI were administered orally or i.m. with a total of 3g of RJ given in 12 equal doses of 250 mg per ewe per day starting at the time of sponge insertion. At the time of sponge withdrawal (day 0, 0 h), ewes were exposed to three rams and checked for breeding marks at 6-h intervals for 3 days. Blood samples were collected from all ewes for analysis of progesterone concentrations. Pretreatment progesterone levels were <0.5 ng x ml(-1) in 16/30 and >1.3 ng x ml(-1) in the remaining ewes indicating luteal function and cyclicity. Similar reproductive responses and progesterone levels occurred in ewes of the RJC and RJI; therefore, data of the two groups were pooled. Following sponge insertion, progesterone levels increased rapidly and reached maximum values of 5.8+/-0.2 ng x ml(-1) within 2 days among ewes of the three groups, and then declined gradually to day 0 values of 1.6+/-0.1 and 1.9+/-0.1 ng x ml(-1) for the RJ-treated and CON ewes, respectively. The rate of progesterone decline was greater (P<0.001) in RJ-treated than in CON. Mean progesterone levels during the 12-day period were lower (P<0.001) in RJ-treated than in CON (2.8+/-0.2 ng x ml(-1) versus 3.3+/-0.2 ng x ml(-1)). Treatment with RJ resulted in greater (P<0.05) incidence of oestrus and shorter (P<0.05) intervals to onset of oestrus than CON. Based upon progesterone levels, ovulation occurred following day 0 in all ewes. Progesterone increased on day 3 in RJ-treated and on day 4 in CON ewes. Progesterone remained elevated through day 18 in 8/20 RJ-treated and 1/10 CON ewes (P=0.09). All pregnant ewes exhibited oestrus 14 h earlier (P<0.02), ovulated approximately 1 day earlier and had higher (P<0.001) luteal phase progesterone levels than non-pregnant ewes. Non-pregnant had higher (P<0.04) body weights than pregnant ewes. In conclusion, results demonstrate that both RJ treatments in conjunction with exogenous progesterone were equally capable of improving oestrus response and pregnancy rate.     

Plasma and fecal progestagen evaluations during and after the breeding season of the female vicuna (Vicuna vicuna )

Plasma and fecal progestagen patterns of female (n = 10) vicunas (Vicuna vicuna ) were determined about 1 to 2 mo before and until 4 mo after breeding. The vicunas were caught wild and were penned at the Lauca National Park (Chile, 4470 m above sea level) for 7 mo (December to June). Plasma and fecal samples before and during the mating period (January to March) were collected 4 to 5 times weekly, and once or twice weekly thereafter. The samples were analyzed by enzymeimmunoassays (EIA) using antibodies against progesterone and 20alpha-dihydroprogesterone. High performance liquid chromatography (HPLC) separations confirmed that progesterone and 20alpha-dihydroprogesterone predominated in the plasma, whereas in the feces several unconjugated, immunoreactive progestagen metabolites containing either a 20-oxo- or a 20alpha-OH-group occurred. The coefficients of correlation (n = 409; P < 0.01) between matched plasma and fecal samples were 0.39 and 0.53 for 20-oxo- and 20alpha-progestagens, respectively. Elevated (5 to 6 d) plasma and corresponding fecal progestagens after mating indicated cyclic corpus luteum activity in 5 of the animals. After the mating period (23.2 +/- 3.3 d), corpus luteum function in these 5 animals persisted, as it did in 3 other animals that were not observed to be mating. The persisting corpus luteum function was demonstrated by increased mean plasma and fecal progestagen concentrations (> 1 ng/ml and > 100 ng/g, respectively). Mean plasma 20alpha-dihydroprogesterone concentrations exceeded that of progesterone by about 1 ng/ml (P < 0.01). The results demonstrated that in addition to plasma progesterone, plasma 20alpha-dihydroprogesterone and noninvasive fecal progestagen evaluations are useful, valid tools for determining corpus luteum function in vicunas.     

Induction of parturition, progesterone secretion, and delivery of placenta in beef heifers given relaxin with cloprostenol or dexamethasone

Sixty primiparous beef heifers from a crossbreeding study were used to examine the effects of inducing parturition with relaxin (3,000 U/mg) combined with cloprostenol (500 micrograms, i.m., n = 30) or dexamethasone (20 mg, i.m., n = 30) at Day 273, 10 +/- 1 days before expected parturition (Day 283). Heifers were assigned at random within cloprostenol and dexamethasone groups to receive relaxin (1 mg, n = 5/treatment), i.m. or in the cervical os (OS), at 0 h (the same time as cloprostenol and dexamethasone) or 24 h later. Eleven and six first-calving heifers and sixteen and nine second-calving cows also received cloprostenol + relaxin and cloprostenol + phosphate-buffered saline, respectively. Radioimmunoassay of daily plasma samples indicated an abrupt decrease in progesterone with time (p less than 0.001), from 7.5 +/- 0.50 to 1.0 +/- 0.30 ng/ml (mean +/- SE) within 48 h for all groups. The mean rate of progesterone decrease (ng/ml in 24 h) was accelerated (p less than 0.01) in relaxin-treated heifers (5.3 +/- 0.36), in contrast to dexamethasone- and cloprostenol-treated control heifers (2.8 +/- 0.40). Relaxin combined with cloprostenol or dexamethasone shortened the calving period in these heifers by reducing the interval between treatment and calving (33 vs. 56 h; p less than 0.01). The incidence and duration of retained placenta were reduced by 22 vs. 75% and 14 vs. 34 h for relaxin combined with cloprostenol or dexamethasone as compared with cloprostenol- or dexamethasone-treated controls, respectively (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Ovarian function in the elephant: luteinizing hormone and progesterone cycles in African and Asian elephants

Serum samples were collected weekly for 3 yr from two female African elephants, for 18 mo from two other female African elephants, and for 2 yr from two female Asian elephants. Animals were not sedated at the time of blood collection. Ovarian cycles, characterized by changes in progesterone and immunoreactive luteinizing hormone (ILH) concentrations, averaged 15.9 +/- 0.6 wk (N = 25) for African females and 14.7 +/- 0.5 wk for Asian females (N = 10). The length of the active luteal phase averaged 10.0 +/- 0.3 wk for African elephants (range 8-14 wk) and 10.6 +/- 0.6 wk for Asian females (range 9-13 wk). Interluteal phases were 5.9 +/- 0.6 wk for African females and 4.2 +/- 0.5 wk for Asian females. One African female (Maliaca) had two extended interluteal phases, both occurring between the months of February and May. Excluding these two periods, there were no differences in the length of the ovarian cycle or the length of the luteal phase between species of elephant. Serum progesterone in both species ranged from less than 50 pg/ml to 933 pg/ml. Average progesterone concentrations during the luteal phase were significantly lower in African elephants compared with Asian elephants (328 +/- 13, N = 30 cycles vs. 456 +/- 23, N = 14 cycles; p less than 0.001). ILH ranged from nondetectable to 11.6 ng/ml. These data suggest that the length of the ovarian cycle in the African elephant is about 16 wk and confirm that the length of the ovarian cycle in the Asian elephant is about 15 wk.     

Fixed-time artificial insemination of postpartum beef cows at 72 or 80 h after treatment with the MGA Select protocol

The objective was to determine the appropriate timing of fixed-time artificial insemination (AI) following administration of the MGA Select protocol. Cows at two locations (Location 1, n=114; Location 2, n=97 ) were assigned to fixed-time AI at 72 or 80 h by age, body condition score (BCS), days postpartum (DPP), AI technician, and sire. All cows were synchronized with the MGA Select protocol, consisting of oral administration of melengestrol acetate (MGA; 0.5mg/hd per day) for 14 days, GnRH (Cysotrelin, 100 microg, i.m.; Day 26) 12 days after MGA withdrawal, followed in 7 days with PGF(2alpha) (PG; Lutalyse, 25mg i.m.; Day 33). Cows were inseminated at 72 h ( n=108 ) or 80 h ( n=103 ) after PG and GnRH (100 microg) was given at insemination. Location was not significant and, therefore, was removed from the model. Mean BCS ( 5.2+/-0.1, 72 h; 5.3+/-0.1, 80 h) and DPP ( 34+/-2, 72 h; 35+/-2, 80 h) did not differ ( P>0.1 ) between treatments. Serum progesterone concentrations 7 and 1 day prior to MGA were used to determine pre-treatment cyclicity: cows with at least one sample with progesterone > or =1 ng/ml were defined as cyclic (33/108, 31%, 72 h, versus 32/103, 31%, 80 h; P>0.1). Cows with serum progesterone concentrations > or =1 ng/ml on the day of PG were defined as responding to the synchronization protocol (74/108 (69%), 72 h versus 69/103 (67%), 80 h; P>0.1 ). Although pregnancy rates were higher ( P<0.05 ) for cows inseminated at 72 h (69/108, 64%) versus 80 h (52/103, 50%) after PG, pregnancy rates at the end of the breeding season did not differ ( P>0.1 ) between treatments (98/108 (91%), 72 h; 88/103 (85%), 80 h). In conclusion, pregnancy rates were higher when postpartum beef cows synchronized with the MGA Select protocol were inseminated at 72 h versus 80 h after PG.     

The effect of two different levels of progesterone priming on the response of ewes to superovulation

The use of either 1 or 3 controlled internal drug release (CIDR) devices for progesterone priming in ewes (n=11) superovulated with 1500 IU pregnant mare serum gonadotrophin (PMSG) at 28 hours prior to CIDR device withdrawal was investigated in relation to the stages of development and viability of the ova produced. Progesterone levels in the ewes (n=6) treated with 3 CIDR devices were significantly higher (P<0.01) during the 11 days of insertion than in those (n=5) treated with 1 CIDR device (7.3 vs 3.3 ng/ml) over the same period. However, following superovulation, the mean (+/-SEM) ovulation rates were similar for both groups (8.2 +/- 1.7 vs 10.2 +/- 1.5). The number of ova (M+/-SEM) recovered by laparoscopy 5 days after insemination was 4.2 +/- 1.0 for ewes treated with 3 CIDR devices and 7.0 +/- 1.1 for those treated with 1 CIDR device (P<0.10). The respective ovum recovery rates (M+/-SEM) were 55+/-9.8 and 74+/-13.2%. There was no effect of progesterone concentration in the priming phase on either the stages of development of the recovered ova or on their ability to develop during in vitro culture. It was concluded, therefore, that progesterone concentrations within the range 3.3 +/- 0.1 to 7.3 +/- 0.3 ng/ml during the priming phase and 2.4 +/- 0.3 to 6.5 +/- 0.2 ng/ml at the time of PMSG administration did not affect the ovulation rate or the viability of ova recovered from superovulated ewes.     

Seasonal ovulatory activity and plasma prolactin concentrations in the Spanish ibex (Capra pyrenaica hispanica) maintained in captivity

Seasonal changes in ovulatory activity, assessed by the measurement of plasma progesterone and plasma prolactin concentrations were monitored in 10 Spanish ibex females captured in the National Wildlife Reserve of Sierra Nevada (South Spain, 37 degrees N). Five of the 10 female ibex showed ovulatory activity with a mean (+/- s.e.m.) duration of the oestrous cycle of 19.4 +/- 1 days (range: 17-23 days). On average, the five cyclic females weighed 28 +/- 0.9 kg. Progesterone cycles occurred only in animals older than 4 years of age. Ovulatory activity extended from December to January. The duration of the breeding season was 43.2 +/- 7.7 days. Ibex females younger than 4 years of age had a body weight lower (P < 0.01 ) than that of adults and none of them displayed ovulations. Plasma concentrations of prolactin levels were significantly affected by season (P < 0.05), following a trend that was roughly parallel to daylength. The highest values occurred in the spring (119.7 +/- 21.4 ng x mL(-1)) and the summer (139.3 +/- 19.8 ng x mL(-1)), the lowest values in the autumn (26 +/- 7.4 ng x mL(-1)) and in the winter (19.7 +/- 3.2 ng x mL(-1)). Our results showed a very restricted breeding season, despite the fact that the Spanish ibex originates from and lives in a temperate latitude, revealing a remarkably good adaptation to the harsh climatic and nutritional conditions of their mountainous habitat.     

Serum concentrations of oestradiol and progesterone, and sexual behaviour during the normal oestrous cycle in the leopard (Panthera pardus)

Three mature nulliparous female leopards were studied for 5 years. During three separate 6-month periods serum oestradiol and progesterone concentrations were measured at weekly intervals. Oestradiol was elevated over 21 pg/ml for 54 weeks during these 3 periods, and 36 oestradiol peaks (65.8 +/- 6.3 pg/ml (mean +/- s.e.m.), range 21-172 pg/ml) were identified. Daily frequency of feline reproductive behaviours averaged over each week increased from 1.9 +/- 0.2 (n = 93) during weeks with low serum oestradiol concentrations (less than 21 pg/ml) to 5.3 +/- 0.6 (n = 54) during weeks when serum oestradiol concentrations (greater than 21 pg/ml) were high. Increased serum progesterone concentrations (13-98 n/gml) were observed on 5 occasions in 2 leopards housed together. These presumptive luteal phases lasted from 1 to 5 weeks. Baseline progesterone values were 1.6 +/- 0.4 ng/ml (n = 131). No progesterone increments were observed in isolated animals, and serum concentrations remained at baseline levels. These limited observations suggest that female leopards do not require intromission to induce ovulation and luteal function. The average interval between oestradiol peaks for cycles with no progesterone increment was 3.4 weeks (range 1-6 weeks). The interval for the 3 complete cycles associated with elevated progesterone concentrations was 7.3 weeks. Analysis of sexual behaviours over the 5-year study period revealed no evidence of seasonality in these captive leopards.     

Steroid and gonadotropin hormone levels in young African women with filarial infection

Serum levels of dehydroepiandrosterone sulfate (DHEAS), testosterone (T), progesterone (P), estradiol (E2), prolactin (PRL), cortisol (F) and gonadotropins (FSH, LH) were analysed by radioimmunoassay for 125 schoolgirls aged 14-16, in a zone of endemic filariasis 3 days after menses. Two groups were identified: the infected group in which 38 subjects had circulating Loa loa and or Mansonella perstans microfilariae as determined by the Knott's concentration technique, and the non-infected group (87 subjects without microfilaremia). All results are expressed as the mean +/- SD. No significant difference was found between the two groups for age (14.47 +/- 1.37 yr vs 14.50 +/- 1.37 yr) or for body wt (46.10 +/- 8.45 kg vs 47.06 +/- 8.26 kg). There was a tendency to lower levels of DHEAS in the infected group by comparison with controls (54.92 +/- 37.34 micrograms/dl vs 66.80 +/- 47.18 micrograms/dl) while in the same infected group more subjects had higher levels of prolactin by comparison with the control group (10.85 +/- 14.16 ng/ml vs 9.80 +/- 5.56 ng/ml). Testosterone, progesterone, estradiol levels and the LH/FSH ratio were lower in the infected group than in the non-infected group (P: 0.25 +/- 0.12 ng/ml vs 0.33 +/- 0.20 ng/ml, P less than 0.025; T: 0.55 +/- 0.17 ng/ml vs 0.62 +/- 0.19 ng/ml, P less than 0.05; E2: 32.95 +/- 19.63 pg/ml vs 66.98 +/- 54.83 pg/ml, P less than 0.001; LH/FSH: 0.91 +/- 0.44 vs 1.30 +/- 0.84, P less than 0.005) respectively. No significant difference was found between the two groups for F; however FSH levels correlated negatively with F levels only in the microfilaremia group (r = -0.38, n = 38, P less than 0.05). Our results suggest that the presence of microfilaremia in our subjects may have contributed to reduced steroid levels, perhaps by involvement of the cyclic AMP kinase system. These observations may explain the delayed menarche and androgen secretion found during puberty in a similar population living in the same zone of endemic filariasis. Microfilaremia should therefore be considered an environmental factor which mediates endocrine disorders in subjects living in tropical filariasis areas.     

Induction of cyclicity in postpartum anestrous beef cows using progesterone, GnRH and estradiol cypionate (ECP)

The objective of the present study was to determine whether treatment of postpartum multiparous and primiparous anestrous beef cows with an intravaginal progesterone-releasing insert (CIDR) and PGF(2alpha), with and without the addition of GnRH or estradiol cypionate (ECP) at the time of CIDR insertion, is effective in stimulating onset of estrous cycles. Postpartum lactating Angus primiparous (n=47, 2 years of age, 495+/-6 kg) and multiparous (n=76, >or=3 years of age, 553+/-9 kg) cows were assigned by calving date to four blocks spaced 21-day apart. Cows were assigned sequentially by calving date to four treatment groups: (1) PGF(2alpha) (n=30), (2) CIDR-PGF(2alpha) (n=30), (3) GnRH-CIDR-PGF(2alpha) (n=33), and (4) ECP-CIDR-PGF(2alpha) (n=27). Intravaginal CIDR inserts were in place from days -7 to 0. A single 100 microg injection of GnRH or 2 mg ECP were administered on day -7, and 25mg PGF(2alpha) was administered on day 0. Day 0 averaged 38+/-1 day postpartum. Blood samples were collected on days -19, -9, 0, 5, 9, 12, 16, 19, 23, 26, and 30 for determination of plasma progesterone concentrations. Pre-treatment luteal activity (progesterone>or=1 ng/ml) was detected in 19% of primiparous and 8% of multiparous cows. Progesterone concentrations on day 0 were greater (P<0.001) in primiparous (3.2+/-0.3 ng/ml) than multiparous (2.0+/-0.2 ng/ml) cows. Following CIDR withdrawal, progesterone concentrations from days 5 to 30 were used to categorize response profiles as either: (1) treatment-induced onset of estrous cycles, (2) continued anestrus, or (3) spontaneous ovulation and subsequent formation of a CL. Incidence of treatment-induced onset of estrous cycles, which was defined as progesterone concentrations >or=1 ng/ml in three or more consecutive samples from days 9 to 19, was influenced by treatment and parity. Percentages of cows initiating estrous cycles were greater (P<0.001) in the three CIDR-treated groups than in the PGF(2alpha) group (55 and 8%, respectively). Percentages of cows initiating estrous cycles in the CIDR-PGF(2alpha), GnRH-CIDR-PGF(2alpha), and ECP-CIDR-PGF(2alpha) groups were 55, 58, and 52%, respectively. Incidence of treatment-induced estrous cycles in the three CIDR-treated groups of cows was greater (P=0.008) in primiparous (76%) than multiparous (43%) cows. Treatment of postpartum anestrous primiparous and multiparous beef cows with CIDR-PGF(2alpha) approximately 40-day postpartum provides an approach to increase the percentage of cows that have reinitiated estrous cycles by the start of the breeding season.     

Effect of early luteolysis in progesterone-based timed AI protocols in Bos indicus, Bos indicus x Bos taurus, and Bos taurus heifers

The objective of this study was to evaluate the effects of treatment with an intravaginal progesterone-releasing device (CIDR) and estradiol benzoate (EB) on follicular dynamics in Bos indicus (n=23), Bos taurus (n=25), and cross-bred (n=23) heifers. To assess the influence of reduced serum progesterone concentrations during 8 days of treatment with a progesterone-releasing device on follicular dynamics, half of the heifers received PGF at CIDR insertion (Day 0; 3 x 2 factorial design). Mean (+/-S.E.M.) serum progesterone concentrations during CIDR treatment varied (P<0.05) among genetic groups: B. indicus (5.4+/-0.1 ng/mL), B. taurus (3.3+/-0.0 ng/mL), and cross-bred (4.3+/-0.1 ng/mL). Maximum diameter of the dominant follicle (DF) was smaller (P<0.01) in B. indicus heifers (9.5+/-0.5 mm) than in cross-bred (12.3+/-0.4 mm) or B. taurus heifers (11.6+/-0.5 mm). B. indicus experienced lower (P<0.01) ovulation rate (39.1%) than did B. taurus (72.7%) and cross-bred (84.0%). Heifers treated with PGF on Day 0 had lower (P<0.05) serum progesterone concentrations during progesterone treatment. The PGF treatment on Day 0 increased (P<0.01) the diameter of the DF (11.9+/-0.4 mm vs. 10.5+/-0.4 mm). Moreover, greater (P=0.02) ovulation rates (78.8 vs. 54.0%) occurred in heifers treated with PGF on Day 0. In summary, B. indicus heifers had greater serum progesterone concentrations, smaller DF diameter, and a lower ovulation rate compared to B. taurus heifers. Prostaglandin treatment on the day of CIDR insertion reduced serum progesterone during treatment, and resulted in increased maximum DF diameter and ovulation rate.