Estrous Period Research Articles

Infanticide in black capuchin monkeys (Cebus apella nigritus) in Iguazú National Park, Argentina

We report here one observed and two potential cases of infanticide during a brief period of 1 month after a dominant male replacement in one group of black capuchin monkeys in Iguazú National Park, Argentina. We also compile infant disappearances and demographic data in seven groups followed from 1-14 years. Behavioral and molecular data showed that the probability that an infanticidal male would kill his own progeny is very low in this species. Females that lost infants less than 6 months old had shorter interbirth intervals than females whose infants survived (14.12 ± 5.32 months, n=17 vs. 20.42 ± 5.65 months, n=34). Females whose infants die shortly after takeovers mate with the presumed infanticidal male during the most fertile days of their subsequent estrous periods giving this male a high probability of siring the new progeny. We recorded 181 proceptive periods and 52 births from 18 adult females in two groups. Most proceptive periods were concentrated during a conception season, but there was an increase in sexual behavior after male takeovers. Seven females copulated while pregnant after the observed male takeover, an unusual behavior in this species in years of group stability. Of 24 infants born during takeover years, 62.5% did not survive the first year, whereas only 22.5% of 80 infants died in years without male replacements. We found a significant positive association between infant mortality and male takeovers, but not with food provisioning. The main cause of infant mortality in this population is associated with male takeovers. Our results suggest that infanticide can have an important effect on the behavior of this species, selecting for female behaviors that function to reduce infanticide risk.

Different estrous induction protocols during the transition period in lactating turkish saanen does following Ai

The objective of this study was to evaluate the duration of three progestagen treatments for estrous synchronization in lactating Turkish Saanen goats during the transitional period from anestrous. All does (n=60) were divided into three equal groups and the estrous period of the does was synchronized using intravaginal sponges (20 mg FGA) for either 11 days (Group 1), 9 days (Group 2) or 6 days (Group 3). In addition, 24h before sponge removal (on the 10th day, 8th day and 5th day, respectively) each doe was injected with 0.075 mg cloprostenol (PGF2 ) and 500 IU eCG. Cervical artificial inseminations (AI) with frozen-thawed semen were performed at fixed intervals (36 and 48 h) following progestagen withdrawal. The total estrous response following the first withdrawal was 12±6h within 66 h. Time to onset and duration of the induced estrous, and pregnancy rates were recorded to be 30.0%, 100%, 23.9±0.7 h, 29.4±1.3 h, and 28.3%, respectively. There were significant differences between Group 1 and the other groups, in terms of the onset of induced estrus (P<0.05) and estrous response for the first 12±6h (P<0.05) and between Group 2 and Groups 1 and 3 in terms of the duration of induced estrous (P<0.05). Each of the three protocols was effective in inducting and synchronizing estrus in lactating Turkish Saanen goats.

Annual characteristics of estrous activity in wool and hair ewe lambs under subtropical conditions

The increased emphasis placed on lamb production in Brazil points to the need for a better knowledge of the annual pattern of reproductive activity in ewe lambs. This study evaluates the annual estrous activity pattern of hair and wool ewe lambs raised in southeast Brazil. Estrous characteristics were recorded for 12 months in ten Santa Inês and 21 Romney Marsh and Suffolk ewe lambs. Santa Inês ewe lambs exhibited a greater length of the normal estrous cycle (14 to 19 days) than Romney Marsh and Suffolk ewe lambs (17.0 ± 0.1 days vs. 16.5 ± 0.2 and 15.9 ± 0.2 days). All the ewe lambs presented a greater number of periods of estrus per animal per month for single estrous cycles (up to 26 days) during autumn and winter. During spring and summer there was a reduction of this number but this decline varied according to the breed. For Santa Inês ewe lambs the reduction was only significant in the summer. For wool ewe lambs the reduction was significant in both seasons but was more accentuated for Romney Marsh. The Romney Marsh ewe lambs had a more restricted breeding season than Suffolk and both presented optimal estrus activity in autumn and winter. Santa Inês ewe lambs had a continuous distribution of estrous cycles along the year, although presenting a reduction in the number of estrous periods in the summer. The ewe lambs of three breeds presented characteristics of sexual immaturity, like irregular estrous cycles and silent ovulations.

Effect of a Calcium Soap of Fatty Acids on Reproductive Characteristics and Lactation Performance of Fat-Tailed Sheep

Experiments were carried out to study the effect of feeding Megalac, calcium soaps of fatty acids (protected fat), on reproduction and lactation of sheep. In the first experiment, 20 Ghezel and 20 Mehraban cyclic fertile ewes (4-5 years old) were randomly allotted to 4 groups. The control group was fed with a balanced ration and the other groups received the same diet as well as a daily allowance of 40 g non-protected fat (NP), 40 g protected fat (LP), or 80 g (HP) protected fat. The ewes were fed with their respective rations for one cycle length. Blood samples were collected and analyzed for progesterone (P4), cholesterol (CHOL), High Density Lipoproteins (HDL), Low Density Lipoproteins (LDL) and triacylglycerols (TG). The ewes were slaughtered on their next estrous period and the size and number of follicles in ovaries were recorded. There were no significant effects of feeding fat on ovarian weights, cycle length and follicular numbers in each class, or on the size of the largest follicle. Serum concentrations of P4, CHOL, TG and HDL were greater for HP ewes as compared with the control ewes (p<0.05). In the second experiment, effects on lactation and lamb performance of feeding protected fat during mating, late gestation and early lactation were studied in Mehraban ewes. Milk and fat yields on day 25 of lactation were significantly increased by feeding protected fat. Protected fat resulted in lower weight loss in ewes and a higher lamb birth weight. Average daily weight gain of lambs from birth to day 60 and the weaning weight of lambs were increased by feeding protected fat (p<0.05). In conclusion, calcium soaps of fatty acids increased serum P4 between days 10 to 14 of the cycle which may be beneficial to early pregnancy maintenance. Protected fat seemed to have a beneficial effect on milk yield, fat yield, lamb daily gain, lamb birth weight and ewe weight loss.

Reproductive success in relation to dominance rank in the absence of prime‐age males in Barbary macaques

In some primate species dominance rank of males is correlated with reproductive success, whereas in other species this relationship is inconsistent. Barbary macaques (Macaca sylvanus) live in a promiscuous mating system in which males are ranked in a dominance hierarchy that influences their access to females. High-ranking males usually monopolize fertile females during their estrous period and show increased mating activities. Subadult males generally rank below adult males. For Barbary macaque females in the Gibraltar colony, there was no correlation between dominance status and reproductive success. Paternity data for 31 offspring collected over four consecutive breeding seasons were used to test whether male social rank was associated with reproductive success and whether reproductive success was mainly confined to a small number of males. Genetic variation was assessed using 14 microsatellite markers for a dataset of 127 individuals sampled in all five social groups of the Gibraltar colony. Paternity analysis was conducted for offspring in one social group only, where all in-group males were sampled. Eighty-three percent of the offspring could be assigned to an in-group candidate father; none of the extra-group males appeared to have sired an infant. Male dominance rank was not found to contribute to the observed variation in male reproductive output. Fifty-nine percent of the offspring was sired by two low-ranking males, whereas the two top-ranking males sired one-fifth. A highly significant correlation was found for male age and dominance rank. Reproductive success of subadult males might be explained by the gap in the age distribution of male group members. These missing prime males are usually regarded as serious competitors for older males. Subadult males may have gained easier access to females in their absence. In addition, the presence of inbreeding avoidance mechanisms, which might also have overpowered possible rank effects, cannot be excluded.

Estrus cycle asynchrony in wild female chimpanzees, Pan troglodytes schweinfurthii

Although estrous synchrony has been reported in a number of mammalian species, most often among primates, methodological and analytical problems make it difficult to interpret these results. We developed a novel estrous synchrony index and employed a randomization procedure to analyze long-term observations of female chimpanzee (Pan troglodytes schweinfurthii) estrous cycles at the Mahale Mountains National Park, Tanzania. Our results revealed that female chimpanzees at Mahale avoid synchronizing their estrous periods with each other. We also found that birthrates decreased as the breeding sex ratio increased. We suggest that estrous asynchrony decreases female–female competition for mates. Asynchrony may also reduce the potential for male sexual coercion by nonpreferred mating partners.

Immunodetection of Thyroid Hormone Receptor (Alpha1/Alpha2) in the Rat Uterus and Oviduct

The aim of this study was to investigate the immunolocalization and the existence of thyroid hormone receptors (THR) (alpha1/alpha2) in rat uterus and oviduct. For this purpose 6 female Wistar albino rats found in estrous period were used. Tissue samples fixed in 10% neutral formalin were examined immunohistochemically. Sections were incubated with primary mouse-monoclonal THR (alpha1/alpha2) antibody. In uterus, THR (alpha1/alpha2) immunoreacted strongly with uterine luminal epithelium, endometrial gland epithelium and endometrial stromal cells and, moderately with myometrial smooth muscle. In oviduct, they were observed moderately in the epithelium of the tube and the smooth muscle cells of the muscular layer.In conclusion, the presence of THR in uterus and oviduct suggests that these organs are an active site of thyroid hormones.

297 EFFECT OF GONADOTROPIN-RELEASING HORMONE COMPARED WITH ESTRADIOL-17β AT THE BEGINNING OF A SUPERSTIMULATION PROTOCOL ON SUPEROVULATORY RESPONSE AND EMBRYO QUALITY

Success of a superstimulation protocol is largely dependent on avoiding the effects of the dominant follicle. The objective of this study was to determine if gonadotropin-releasing hormone (GnRH) would serve as a suitable alternative to the traditional estradiol-17β in a superstimulation protocol when using a CIDR. Dairy cattle (n = 411) were superstimulated using one of two treatment protocols. The GnRH-treated animals received a CIDR on random days of the estrous cycle (day 0), and GnRH was injected i.m. (100 micrograms of Cystorelin) on day 3. Porcine FSH (Folltropin-V) was administered twice daily in decreasing doses on days 5 to 8, and on day 8, CIDR were removed and 25 mg of dinoprost (PGF2α) was administered twice. The Estradiol-treated animals received a CIDR and 4 mg estradiol-17β i.m. on random days of the estrous cycle (day 0). Porcine FSH was administered twice daily in decreasing doses on days 4 to 7, and on day 7, CIDR were removed and 25 mg of PGF2α was administered twice. All animals were artificially inseminated at standing estrus and at 6-h intervals during estrus. Animals were inseminated a minimum of twice, and those with extended estrous periods were inseminated three times. Animals not showing estrus were inseminated once 48 h after CIDR removal. Seven days following estrus, embryos were collected. For data analysis, animals were divided into lactating cows, dry cows, and heifers. Dosage of FSH for each animal varied according to previous response rates; therefore, animals were further subclassified as high FSH (≥300 mg in 15 mL) or low FSH (&lt;300 mg in 15 mL). As there were no heifers on high FSH, data analysis was done as a 5 � 2 factorial ANOVA. Total number of ova/embryos, quality, development, and fertilization rates were recorded. Analysis of data showed no statistical differences (P &gt; 0.05) between Estradiol- and GnRH-treated groups for number ova/embryos recovered (9.8 � 0.58 v. 9.7 � 0.65), IETS-grade 1 and 2 embryos (4.7 � 0.37 v. 4.5 � 0.41), percentage fertilized (54.1 � 2.5 v. 53.2 � 2.9), and percentage grade 1 and 2 embryos (49.2 � 2.5 v. 49.3 � 2.8), respectively. No significant interactions were found between treatment and lactation status or treatment and FSH dose. Data suggest that GnRH in combination with a CiDR is an effective means of synchronizing follicle wave emergence in a superstimulation protocol. George Seidel, Josh Walker, John Hassler, and Sam Galphin.

Effect of lameness on estrous behavior in crossbred cows

Lameness, a common disease in crossbred dairy cows, badly affects their fertility. To elucidate, if estrous behavior, comprising of duration and expression of certain estrous behavioral sign(s) (EBS), is involved, an estrous expression score system was applied to objectively compare estrous behavior during 27 and 58 estrous periods, respectively, in 17 normal and 37 lame cows kept in a group of 200 cows under loose housing system in tropical India. The cows were detected in estrus and were closely watched daily for 30 min at 0630, 1030, 1430 and 1830 h from the beginning to the end of estrus. The duration of estrus was similar in the normal and the lame cows (18.7 ± 1.2 h versus 17.2 ± 0.9 h) and almost similar EBS were shown by two types of cows, albeit with varying frequency. Standing to be mounted, the highest ranking EBS was shown by equal proportions of the cows in both the groups (76.4% versus 73.0%). A lower proportion of lame cows showed head side mounting (35% versus 53%; P < 0.05). The frequency of standing to be mounted events was lower in the lame than in the normal cows (2.4 ± 0.4 versus 8.0 ± 2.5; P < 0.05). The lame cows earned non-significantly lower than normal estrous behavior score (1100 ± 179 versus 1610 ± 357). Further, the presence of more than one cow simultaneously in estrus enhanced the estrous behavior score in the normal (406.4 ± 63.0 for one cow in estrus versus 793.0 ± 146.0 for three cows simultaneously in estrus; P < 0.05), but not in the lame cows. Lameness appeared to have suppressed the playful behavior during estrus probably owing to pain related stress. It is concluded that mildly lame cows appear to have normal physiological estrus. However, some of the EBS remain subdued which prone them to remain undetected for timely breeding.

Impact of activity space on the reproductive behaviour of giant panda (Ailuropoda melanoleuca) in captivity

We studied the impact of activity space on the reproductive behaviours of eleven healthy adult female and three adult male giant pandas with natural mating ability from the Beijing Zoo, the Lanzhou Zoo, the Chengdu Zoo and the Chengdu Giant Panda Breeding Center during their non-mating and mating season from November 1999 to May 2003. We contrasted the frequencies of reproductive behaviour and activities of the giant pandas that kept in different size of activity spaces during their estrous period and found that the frequencies of reproductive behaviours and other activities of the female and male giant pandas in large activity space were significantly higher than that of those when they were kept in small pens (P<0.05). When the giant pandas were kept in small pens (<12m2), the frequencies of reproductive behaviours occurred at lower level. Once the captive giant pandas were released into a larger playground (>200m2), their reproductive behaviour was expressed at higher frequency. If the giant pandas were confined in pens again from the playground, then their reproductive behaviour would be restrained again by the limited space and the frequency of reproductive behaviour decreased. This reversibility of reproductive behaviour of giant pandas proved that small activity space suppresses the reproductive behaviour of the giant pandas in captivity; the elasticity of reproductive behaviour was high. Therefore, to provide larger activity space to the giant panda in captivity will help them to fully express their behaviour, especially the reproductive behaviour.

Evaluation of intrauterine therapies in repeat Breeder dairy cattle

A total of 160 repeat breeder dairy cows suffering from endometritis were used in this study. The cows were divided into six groups and were subjected to different intrauterine therapy, the first group was treated with 1% of Lugol's solution, the second and third group were treated with 2 gm of Oxytetracycline and chloramphenicol respectively, while the cows in the groups four and five were subjected to an intrauterine therapy with one million units of crystalline penicillin and one tube of metrijet respectively, mean while the group six was untreated and used as a control. The animals in all groups (except the group four) were inseminated on the subsequent estrous period following therapy, while the group four was subjected to post -service treatment within 24 hours after insemination. The cows were inseminated twice with 8 hours a part between them and they were injected intravenously with 1500 I.U of hCG ( chorulon ) when delayed ovulation was suspected . Pregnancy examination by rectal palpation 50 days after the second insemination revealed pregnancy rates ( %74.28 , %72 , %68 , %60 , %40 ) for the six group respectively . The results of the present study showed no significant differences (p> 0.05) among the different treated groups, and when each of the first four treated groups compared with the control one. There was a significant differences between treated and control group (p<0.05). It was concluded that the intrauterine therapies and the injection of hCG at the time of insemination are useful in the treatment of repeat breeder cows.

GnRH agonist Lupron ® (leuprolide acetate) pre-treatments prevent ovulation in response to gonadotropin stimulation in the clouded leopard ( Neofelis nebulosa)

In many species, controlling the ovary prior to induction of ovulation improves the success of ovarian response and artificial insemination (AI). We assessed the impact of suppression of estrus with the GnRH agonist, Lupron ®, on ovarian sensitivity to equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG) in the clouded leopard. Seven female clouded leopards were given two injections of Lupron ® (3.75 mg IM) 23 d apart, followed 44 d later by eCG and hCG. Daily fecal samples were collected from 60 d before Lupron ® to 60 d after hCG. Fecal metabolites of estrogen (E) and progesterone (P) were measured by radioimmunoassay. Lupron ® decreased ( P < 0.05) the number of E peaks during Lupron ® treatment compared to pre-Lupron ®. All females had baseline E and six of seven (86%) had nadir P on day of eCG. Exogenous gonadotropins induced E elevations in all females. However, mean E in the gonadotropin-provoked estrus was decreased ( P < 0.05) compared to pre-Lupron ® estrous periods. Only one of seven (14%) females ovulated after eCG/hCG. In conclusion, estrous cycle control with Lupron ® resulted in predictable ovarian suppression prior to gonadotropin stimulation but altered ovarian sensitivity by an as yet unknown mechanism so that ovulation was inhibited, even when using a proven exogenous gonadotropin protocol.

Male Mate Choice in Lemur catta

Though females are generally more selective in mate choice, males may also derive reproductive benefits from exercising mate selectivity if one or more factors limit male reproductive success and females differ in reproductive potential. I used male mating effort as a proxy for male mate choice in ring-tailed lemurs (Lemur catta). I calculated mating effort as the rate of male-male agonism during each female's estrous period 30 min before and 30 min after the first and last mountings with intromission. I collected data on 1 free-ranging Lemur catta troop during 2 consecutive breeding seasons on St. Catherines Island, USA. In both yrs, male mating effort differed significantly among troop females once I adjusted male-male agonistic rates to reflect agonistic intensity, and I corrected for the number of observed mates per female (2000: χ2 = 27.43, df = 3, p < 0.0001; 2001: χ2 = 21.10, df = 3, p < 0.001). Results strongly suggest male mate choice. Contrary to expectation, males did not expend the greatest mating effort for females with the highest dominance status nor the highest reproductive success. Males preferred females that either: (1) belonged to the age class in which fecundity and infant survival is the highest at this site (4–9 yrs), or 2) were older females (≥10 yrs) with high reproductive success. Female reproductive potential appears to be an important variable determining male mating effort in Lemur catta.

Stereotypic behavior and fecal cortisol level in captive giant pandas in relation to environmental enrichment

Stereotypic behavior is exhibited by a wide range of captive animals. Its association with hormones, especially elevated cortisol level and lack of naturalistic stimuli in the environment, has been little studied. This study hypothesizes that stereotypic behavior is caused by stress due to lack of appropriate, naturalistic stimuli in the environment. Using four adult pandas (Ailuropoda melanoleuca) in the Beijing Zoo from March–July in 2003, we tested the following predictions: 1) stereotypic behavior and fecal cortisol level will not change associated with the progress of reproductive state; 2) there is a positive correlation between the occurrence of stereotypic behavior and fecal cortisol level; and 3) environmental enrichment by adding a naturalistic stimulus will reduce both stereotypic behavior and fecal cortisol level. We did not find any significant differences in the occurrence of stereotypic behavior and fecal cortisol level but did find a significant difference in the total time engaged in displaying the stereotypic behavior among the three estrous periods. The level of stereotypic behavior was correlated with elevated fecal cortisol level. Enrichment simply by adding a naturalistic stimulus did not show significant effects on stereotypic behavior, or on fecal cortisol level. Our results supported the second prediction, but did not completely support the first and the third ones perhaps because of the small sample size. Additionally, our results showed that stereotypic behavior might be a response to a heightened level of cortisol. Zoo Biol 0:1–15, 2006. © 2006 Wiley-Liss, Inc.

Peripheral Plasma Progesterone: A Marker for Determining Cyclicity in Yaks (Poephagus grunniens L.)

An attempt was made to determine cyclicity in yaks using plasma progesterone during the breeding and non-breeding seasons. Fifteen non-lactating yaks were used in this experiment. During the breeding season (July to November), blood samples were collected from 8 yaks at least twice weekly until estrus was observed and then at 2 days interval for 30 days. During the non-breeding season (February to March), blood samples were collected from the same number of yaks at 2-day interval for 30 days. Progesterone was determined in plasma samples by radioimmunoassay. During the breeding season, plasma progesterone at estrus was basal (< or = 0.2 ng/ml). Concentrations increased thereafter with a sharp increase during the late luteal phase, typically reaching peak levels around day 15. Concentrations then declined rapidly over the following 4 days, reaching basal levels at estrus. A high proportion (66.7%) of potential estrous periods (based on progesterone concentrations) went undetected, indicating that silent or weak estrus was a prominent problem in yak cows. During the non-breeding season, three animals were found to be cycling as determined by the patterns of plasma progesterone. Yet, behavioral symptoms of estrus were not observed in any of these yak cows. We conclude that peripheral plasma progesterone concentrations can be used to monitor cyclicity in yak cows effectively.

Estrous response to synchronization of estrus using different progesterone treatments outside the natural breeding season in ewes

A trial was conducted to investigate the efficiency of synchronization using different progesterone treatments outside the natural breeding season. Ninety multiparous Karakul ewes were randomly assigned to one of three treatment groups ( n = 30/group). In the progesterone treated group, ewes were injected intramuscularly (i.m.) with 20 mg progesterone acetate in oil every second day for 12 days, plus an i.m. injection of 500 IU eCG on day 12. The CIDR treated group, the animals were treated with the intravaginal devices impregnated with 0.3 g of progesterone for 12 days and injected i.m. with 500 IU eCG at withdrawal while in the third group, the ewes were treated with MAP sponges impregnated with 60 mg medroxyprogesterone acetate (MAP) for 12 days and injected i.m. with 500 IU eCG at sponge withdrawal. The interval from the cessation of treatment to the onset of estrus was significantly ( p < 0.05) longer in the progesterone in oil group, compared to CIDR and MAP sponge groups (51.4 ± 10, 30.1 ± 7.6 and 29.6 ± 5.6 h, respectively). The estrous response for the sponge and device groups was higher, compared to the group injected with progesterone (93.3% for CIDR, 100% for MAP sponge and 80% for the oil treated group). The duration of the induced estrous period did not differ significantly between the treatment groups. The results of the present study show that estrous synchronization with CIDR and MAP sponge followed by an i.m. administration of eCG is superior under local conditions for fixed time AI in Karakul ewes outside the natural breeding season.

Pedometer readings for estrous detection and as predictor for time of ovulation in dairy cattle

The objective of this study was to study the relationship between increase in number of steps measured by pedometers, behavioral estrous parameters and time of ovulation, in order to investigate whether the number of steps can be used as a tool for estrous detection and as a predictor for time of ovulation. In total, 63 ovulations were observed in 43 Holstein-Friesian cows. Different behavioral signs of estrus were observed at 3 h intervals. Cows were equipped with pedometers, which stored number of steps in 2 h time periods and pedometer estrus alerts were defined using different algorithms and thresholds. The percentage of behavioral estruses also detected by pedometers measurements, ranged between 51 and 87% for all estrous periods. When only estrous periods where taken into account in which more than one animal was in estrus, detection percentages increased up to 95%. Number of steps taken during the estrous period was higher when more animals were in behavioral estrus at the same time, and number of steps taken during the estrous period was also higher for primiparous cows compared to multiparous cows. Ovulation occurred 29.3 ± 3.9 h after onset of increased number of steps (ranging between 39 and 22 h) and 19.4 ± 4.4 h after the end of increased number of steps (ranging between 35 and 12 h). The intervals were not influenced by the number of animals that were in estrus at the same time or by parity. In conclusion, pedometers can detect estrus accurately and appear to be a promising tool for prediction of ovulation and hence could be a tool for improving fertilization rates.

ニホンザルのビジランスを規定する社会的要因

The present study investigated vigilance in Japanese macaques (Macaca fuscata) in reference to some social factors. Previous studies have suggested that social factors among conspecifics should be important for vigilance in primates. This study explored the relationship between individual's social rank and vigilance in estrous and non-estrous periods in female Japanese macaques. With a video camera, I recorded vigilance of 23 females among approximately 170 individuals of Arashiyama E-troop. The results were as follows. High degree of vigilance was observed in three conditions, 1)females in estrous period regardless of the rank, 2)low-ranking females in nonestrous period, and 3)females in estrous period consorting with low-ranking males. These results indicate that social relationship is an important factor which affects the degree of vigilance in female Japanese macaques.

Relationships between patterns of Fecal corticoid excretion and behavior, reproduction, and environmental factors in captive black (Diceros bicornis) and white (Ceratotherium simum) rhinoceros

Mortality is high in zoo-housed black rhinoceros (Diceros bicornis), and the reproductive rates of captive white rhinoceros (Ceratotherium simum) are unsustainably low. To determine the possible role of stress in the causation of these problems, we analyzed weekly fecal samples collected for 1 year from black (10 males and 16 females) and white (six males and 13 females) rhinoceroses at 16 zoos for corticoid metabolite concentrations. Fecal corticoid profiles were examined in relation to behavior as rated by keepers in a questionnaire, luteal phase ovarian cycles of females (Brown et al., 2001), and socioenvironmental factors. We compared individual fecal corticoid profiles by examining hormone means and variability (i.e., standard deviation (SD) and coefficient of variation (CV)). For the black rhinos, higher mean corticoid concentrations were found at zoos where rhinos were maintained in enclosures that were exposed to the public around a greater portion of the perimeter. Higher variability in corticoid excretion was correlated with higher rates of fighting between breeding partners and higher institutional mortality rates. Black rhino pairs that were kept separated exhibited lower corticoid variability and less fighting activity when they were introduced during female estrous periods compared to pairs

The hormonal profile during the estrous cycle and gestation in Damascus goats

Plasma progesterone, estradiol, LH, FSH and prolactin levels were studied before and during an estrous cycle in 11 Damascus does, exposed to different suckling regimens (Group A: does suckled for 60 days; Group B: does suckled for 120 days; Group C: non-lactating does). In addition, plasma progesterone levels were determined during pregnancy in 10 pregnant does. The mean plasma progesterone levels in the lactating does before the onset of the first postpartum estrus, which included the follicular phase, were significantly lower (0.2 ± 0.1 and 0.1 ± 0.02 ng/ml, respectively), compared to the luteal phase (5.4 ± 0.9 and 2.6 ± 0.3, respectively). The mean plasma progesterone levels in non-lactating does prior to and after the onset of the first seasonal estrus were 0.5 ± 0.1 and 3.3 ± 0.4, respectively. A decline in plasma progesterone concentration was observed 24–72 h before the second postpartum (Groups A and B) and seasonal (Group C) estrus, indicating CL regression occurring in all does. The mean plasma progesterone concentrations in pregnant does reached a value of 4.6 ± 2.8 ng/ml at week 2 of gestation, and increased to a level of 24.5 ± 3.1 ng/ml 12 weeks later. During the luteal phase estradiol levels in the does of Groups A–C were lower (45.7 ± 3.1, 30.8 ± 1.4 and 61.04 ± 6.5 pg/ml, respectively) than the first peak, whether at the onset of postpartum (Groups A and B) seasonal estrus (Group C), or during the estrous period (46.1 ± 5.9, 41.6 ± 5.2 and 93.1 ± 39.5 pg/ml, respectively). The difference in the profiles of plasma estradiol levels at the first and the second postpartum (Groups A and B) seasonal (Group C) estrus may be due to the negative effect of progesterone levels. An LH surge was detected in only two lactating does in Group A (59.3 and 33.6 mIU/ml) 24 and 32 h after the onset of the second postpartum estrus following an increase in plasma estradiol concentration. Plasma FSH levels fluctuated in all groups with no distinct trend during the estrous cycle. Prolactin levels at the onset of the postpartum (Groups A and B)/seasonal (Group C) estrus were higher than levels detected before and during estrous period. The Damascus does manifested great variation in hormonal profiles of the individual animals. All does showed normal cycles, not affected by the different suckling regimens or lactation.