Monitoring reproductive status by fecal progesterone analysis in ruminants

The role of chromosome variation in the speciation of the red brocket deer complex: the study of reproductive isolation in females

BACKGROUND

The red brocket deer, Mazama americana, has at least six distinct karyotypes in different regions of South America that suggest the existence of various species that are today all referred to as M. americana. From an evolutionary perspective, the red brockets are a relatively recent clade that has gone through intense diversification. This study sought to prove the existence of post-zygotic reproductive isolation in deer offspring between distinct chromosome lineages. To achieve this, inter-cytotype and intra-cytotype crosses were performed, which resulted in both F1 hybrid (n = 5) and pure offspring (n = 3) in captivity.

RESULTS

F1 females were analyzed in terms of their karyotypes, ovarian histology, estrous cycles and in vitro embryo production. Pure females presented parameters that were similar to those previously reported for M. Americana; however, the parameters for hybrid females were different. Two hybrids were determined to be sterile, while the remaining hybrids presented characteristics of subfertility.

CONCLUSIONS

The results support the existence of well-established reproductive isolation among the most distant karyotype lineages and elucidates the need to define all karyotype variants and their geographical ranges in order to define the number of species of red brocket.

Fecal steroid analysis for evaluating ovarian function in the greater kudu (Tragelaphus strepsiceros) and lesser kudu (Tragelaphus imberbis)

Seasonal reproductive-endocrine norms have not been described for the genus Tragelaphus, which consists of seven species of African antelope. Longitudinal patterns of progesterone metabolite excretion were assessed by radioimmunoassays in fecal samples collected noninvasively (three to seven samples per week) from greater kudu (Tragelaphus strepsiceros, n = 4) and lesser kudu (Tragelaphus imberbis, n = 4). Progesterone metabolite excretion patterns revealed seasonal estrous cycles in both species, and discrimination of pregnant versus nonpregnant females was achieved in lesser kudu. These data reveal the value of fecal progesterone metabolites for establishing reproductive-endocrine norms in both zoo-maintained and free-living antelopes of the genus Tragelaphus.

Variation in fecal testosterone hormone concentration with season and harem size in Misaki feral horses

On Misaki peninsula, Japan, fecal samples were collected from 14 Misaki stallions at monthly intervals for 12 consecutive months. The fecal testosterone concentration was measured by radioimmunoassay. We examined monthly fecal testosterone hormone patterns and the relationship between fecal testosterone concentration and breeding season and later harem size. Marked monthly variations in fecal testosterone concentration were observed. The fecal testosterone concentration began rising in March; the highest mean monthly concentration, 2.87 +/- 0.18 ng/g, was found in April, and the level remained elevated until the end of August and thereafter decreased. A significant correlation was found between the fecal testosterone concentrations and harem size in both the breeding and non-breeding season among the 14 stallions. It is therefore possible that the testosterone levels in feces, instead of blood, correlate very well with harem size in Misaki stallions. Our findings emphasized that the fecal testosterone concentration can be a powerful indicator for monitoring of endocrine status in wild stallions.

Plasma and fecal sex steroid hormone profiles during the estrous cycle in a Japanese serow (Capricornis crispus)

We aimed to determine plasma progesterone and estradiol-17beta concentrations, as well as fecal progesterone concentrations during the estrous cycle in a female 8-year-old Japanese serow (Capricornis crispus). The step frequencies during the night were recorded by a pedometer attached to the serow's hind leg from October to the following June. Estrous behavior was also monitored during the day. Blood samples were taken once a day from 8 February to 10 March from an indwelling catheter placed in the jugular vein. Fecal samples were taken once or twice a day from 1 January to 29 April. Plasma and fecal progesterone and plasma estradiol concentrations were determined using time-resolved fluoroimmunoassays. The estrus behavior observed lasted for 2-3 days. Peak step frequencies were recorded between November and April, at intervals of 17-19 days. Plasma progesterone concentrations remained elevated (1-7.7 ng/ml) for 12 days during non-estrus, and plasma estradiol concentrations were highest when the peak step frequency and estrous behavior were observed. Step frequency increased around the times fecal progesterone levels fell to basal levels. Progesterone concentrations in feces were significantly correlated with those in sera. Thus, measurement of fecal progesterone concentrations might be useful for monitoring the reproductive status of the Japanese serow.

Measurement of Faecal Progesterone Metabolites and its Application for Early Screening of Open Cows Post-insemination

The present study investigated the changes of serum progesterone (P4) and its faecal metabolites in pregnant and non-pregnant cows (Expt 1) and the feasibilty of using faecal P4 metabolites for early screening of open cows post-insemination (Expt 2). In Expt 1, seven crossbred Holstein-Friesian (HF) cows were studied. Serum and faecal samples were collected once daily from the day of artificial insemination (AI) until 25 days after AI. In Expt 2, 27 crossbred HF inseminated cows were employed. Serum and faecal samples were obtained on the day of AI (day 0) and on days 19-22 post-insemination. Enzyme immunoassay measurements of serum P4 and faecal P4 metabolites were established. The low detection limit of the assay was 0.01 ng/ml and the amount of P4, resulting in a 50% reduction in the initial binding value, was 1.07 ng/ml. The intra- and inter-assay coefficients of variation were <8% and <14%, respectively. A positive correlation between the levels of serum P4 and faecal P4 metabolites was found in every single cow (r = 0.73-0.88, p < 0.001) and pooled data (r = 0.78, p < 0.001). The estimated value of faecal P4 metabolites at 100 ng/g of faeces was equal to the serum P4 levels of 1 ng/ml. The accuracies of pregnancy and non-pregnancy diagnosis based on the analyses of faecal P4 metabolites between day 0 and days 19-22 post-insemination, were 67% and 100%, respectively. In conclusion, the measurement of faecal P4 metabolites can be a potentially alternative method for early screening of open cows post-insemination with the same accuracy and precision, as measured by serum P4 assay.

Immunolocalization of steroidogenic enzymes in the corpus luteum and placenta of the Japanese Shiba goat

In this study, we performed immunohistochemistry of cholesterol side-chain cleavage cytochrome P450 (P450scc), 3beta-hydroxysteroid dehydrogenase (3betaHSD), cytochrome 17alpha-hydroxylase P450 (P450c17), and cytochrome P450 aromatase (P450arom) in the corpus luteum and placenta of Shiba goats. The aim was to clarify the steroidogenic capability of the corpus luteum and placenta of Shiba goats. Ovaries containing corpora lutea were obtained from four adult Shiba goats during the luteal phase (day10; n=2) and pregnancy (90 and 120 days of gestation). Placenta was obtained from one Shiba goat on day 120 of gestation. The sections of the ovaries and placentae were immunostained using the avidin-biotin-peroxidase complex method (ABC) with polyclonal antibodies generated against steroidogenic enzymes of mammalian origin. All luteal cells expressed P450scc, 3betaHSD, P450c17 and P450arom. The distribution of P450scc, 3betaHSD, P450c17 and P450arom were not different during the luteal phase and pregnancy. P450arom showed a weak positive staining in late pregnancy (120 days). In addition, immunoreactions for P450c17 and P450arom were observed in syncytiotrophoblast of the placenta of one Shiba goat. These results indicate that, in Shiba goats, corpus luteum is not only an important source of progesterone but also has the ability to synthesize androgen and estrogen during the luteal phase and pregnancy. Also the placenta has the ability to synthesize androgen and estrogen in late pregnancy.

Immunolocalization of Nerve Growth Factor (NGF) and Its Receptors (TrkA and p75LNGFR) in the Reproductive Organs of Shiba Goats

The objective of this study was to determine the immunolocalization of NGF and its receptors (TrkA and p75LNGFR) in the reproductive tract of the Japanese Shiba goats. Five adult goats were used in this study and sections of ovaries, uteri and oviducts were immunostained by the avidin-biotin-peroxidase complex method (ABC). The results showed that NGF and its receptors (TrkA and p75LNGFR) were expressed in granulosa cells, theca cells, interstitial cells and lutein cells in ovaries. Immunoreactions for NGF, TrkA and p75LNGFR were also detectable in epithelial cells and muscle cells of the ampulla and isthmus of the oviduct, and in epithelial cells and uterine glands of the uterus. These results strongly suggest autocrine and paracrine regulation of reproductive function by NGF in the reproductive tract of female Shiba goats.

Body Growth and Plasma Concentrations of Metabolites and Metabolic Hormones during the Pubertal Period in Female Shiba Goats

It has been shown in various species that the onset of puberty is closely associated with body growth and nutritional state rather than age. The present study was conducted to determine the timing of puberty and to clarify body growth and metabolic changes around the pubertal period in female Shiba goats. Blood samples were collected between 10 to 38 weeks of age from 12 female goats, and plasma concentrations of progesterone, metabolites (glucose, nonesterified fatty acid, ketone body and acetic acid) and metabolic hormones (insulin and insulin-like growth factor-I (IGF-I)) were analyzed. Physical parameters (body weight, withers height and body length) were also measured at the blood sampling. The week when plasma progesterone concentrations first exceeded 1.0 ng/ml was designated as the onset of puberty. The results showed that the average age of the onset of puberty was 27.0 +/- 0.9 (mean +/- SEM) weeks in female Shiba goats. When the goats reached puberty, the average values of body weight and goat body mass index ((body weight (kg)/withers height (cm)/body length (cm)) x 10(3)) were 12.2 +/- 0.5 kg and 5.7 +/- 0.2, respectively. No particular change associated with puberty was apparent for plasma concentrations of the metabolites examined. Plasma insulin concentrations were maintained at lower levels until the onset of puberty, and then they began to gradually increase. Plasma IGF-I concentrations began to gradually increase 1 to 4 weeks before the onset of puberty and this increase continued throughout the peripubertal period. These results imply that IGF-I acts as a peripheral nutritional signal to trigger the onset of puberty in Shiba goats.

Fecal progesterone analysis by time-resolved fluoroimmunoassay (TR-FIA) for monitoring of luteal function in the sika doe (Cervus nippon centralis)

Fecal progesterone content was measured by time-resolved fluoroimmunoassay (TR-FIA) in the sika doe (Cervus nippon). The total recovery rate of fecal progesterone by twice extraction with diethylether was about 60%. The displacement curve of TR-FIA with serial doses of fecal extract (0.156-5.0 mg feces) was closely parallel to that of the reference standard. Fecal progesterone content was correlated with that of plasma (r=0.829, n=16), but the values were 100-fold higher in feces than in plasma. Fecal progesterone content periodically changed during the breeding season suggesting the estrous cycle in the doe. The fecal progesterone content was higher between the estruses, and decreased after estrus. The time between the onset of estrous signs and the lowest fecal progesterone content was 1-2 days suggesting the time required for hepatic metabolism and intestinal passage. Fecal progesterone content was also decreased around the time of vaginal discharge. The discharge took place within a few days, suggesting a short luteal phase. Not of all decreases in fecal progesterone values were preceded by estrous behavior or vaginal discharge. Fecal progesterone content was further increased in pregnancy rather than in the preceding estrous cycle and the levels were maintained up to term. These results suggest that fecal progesterone measurement is a useful tool for non-invasive analysis of luteal function in the sika doe. The TR-FIA kit, designed for the human hospital market, was shown to be successfully utilized for fecal assay in the sika doe with minor modifications.

Annual changes in fecal estradiol-17beta concentrations of the sun bear (Helarctos malayanus) in Sarawak, Malaysia

Fecal estradiol concentrations were measured in three captive unmated female sun bears (Helarctos malayanus) from August 1998 to July 1999 in Sarawak, Malaysia and vaginal smears from one of the females was observed in August 1998 and March 1999. A single peak in fecal estradiol concentration was obvious for each bear in August or September 1998, and there was a much higher percentage of superficial vaginal anuclear cells in August 1998 than in March 1999. These results suggest that sun bears in Sarawak are likely to be a seasonal breeder associated with a peak of estrogen production in August or September.

Reproductive pattern of the sun bear (Helarctos malayanus) in Sarawak, Malaysia

Fecal progesterone assays were conducted in 3 captive female sun bears (Helarctos malayanus) segregated from males to characterize the species-specific reproductive pattern in their original distribution area in Sarawak, Malaysia. Peaks of fecal progesterone concentrations were observed once annually, and lactation was observed after increasing progesterone concentrations in all females without mating stimulus. These results suggest that sun bears in Sarawak, Malaysia, may have a seasonal reproductive pattern and ovulation was noted to occur spontaneously, followed by pseudopregnancy.

Comparison of various reproductive status in Sika deer (Cervus nippon) using fecal steroid analysis

The feasibility of fecal steroid analysis for pregnancy diagnosis and sex determination were tested in sika deer (Cervus nippon). Feces were collected from captive sika deer in June (non-breeding season and late-pregnancy period) and October (breeding season), and also from the rectum of 24 female sika deer (19 pregnant and 5 non-pregnant females) shot as part of programs for population control in February and March (mid-pregnancy period). In mid- and late-pregnancy periods, fecal progesterone concentrations were significantly higher in pregnant female than in male and non-pregnant female deer. In October, fecal testosterone concentrations were higher in adult male deer, and no difference was found between young males and females. These results suggest that fecal steroid analysis would be a useful means for estimating pregnancy status and for detecting adult male among wild deer.

Recent advances in noninvasive techniques to monitor hormone-behavior interactions

This paper reviews recent advances in field endocrinology, a focus as well as a method in primatology and behavioral ecology that permits the examination of social behavior and life history through hormonal investigations in natural settings. Endocrine data complements the traditional behavioral data collected by field scientists by providing quantitative measures for the examination of adaptive tradeoffs, costs of social strategies, and reproductive and social significance of mating events. Further, investigations of the physiological mechanisms of reproductive constraint provide tests of the adaptive significance of reproductive skew in cooperative and competitive breeders. Hormone data also can provide insights into the costs of competition and aggression and the role of temperament in individual reproductive success and the evolution of social systems. New, noninvasive methods for the collection of this information have augmented and expanded field endocrinology through the use of techniques that do not require potentially confounding physical or physiological manipulations. Specifically, urine and fecal samples can be collected from free-ranging animals and contain gonadal and adrenal hormones that parallel profiles of serum hormones. Sampling, preservation, extraction, and assay methods for the analysis of excreted steroids are reviewed along with the species and questions to which these methods have been applied.

Measurement of gestagen concentration in feces using a bovine milk progesterone quantitative test EIA kit and its application to early pregnancy diagnosis in the sow

We attempted to measure the gestagen concentration in the feces of pigs by using a commercial bovine milk progesterone quantitative test EIA kit, and investigated the possibility of applying of this method of gestagen concentration measurement to early pregnancy diagnosis in the sow. Feces were collected from the rectum of the pig, and 0.5 g of the feces was placed in 20 ml of distilled water, stirred, and centrifuged. The supernatant was used as the fecal solution for measurement of gestagen. The procedure used for measuring gestagen in feces was the same as that for the measurement of progesterone in milk, except that a standard fecal gestagen solution (0.5-30.0 ng/ml) was prepared by the authors in the laboratory. The sensitivity of measurement using this method was 0.80 ng/ml, or 32.0 ng/g of fecal weight. The recovery was 105.2-105.6%. Intra-assay coeffecients of variation (CVs) were 2.8-8.5%. The interassay CVs were 7.4-10.2%. Gestagen concentrations in feces measured by the present method and progesterone concentrations in peripheral plasma, collected at the same time as the feces were highly correlated (r = 0.98, p < 0.001). The criteria for diagnosis of pregnancy based on the fecal gestagen level was positive for a gestagen level of > or = 200 ng/g and negative for a gestagen level of < 200 ng/g. When fecal gestagen measurements were applied to early pregnancy diagnosis in 149 sows, the accuracy of diagnosis from day 21 to day 25 after the last mating was 96.2% for positive cases (102/106) and 95.3% for negative cases (41/43). Thus, the results of this study show the quantitative measurement of the fecal gestagen concentration in the sow using a bovine milk quantitative test EIA kit is a practical method for early pregnancy diagnosis.