Restoration of reproductive potential after expiration or removal of melengestrol acetate contraceptive implants in Tigers (Panthera tigris)

The need for contraception in the successful management of captive wild animals is becoming increasingly apparent. Because concerns exist regarding the reversibility of the contraceptive implant melengestrol acetate (MGA), reproductive data for 94 female Amur (Panthera tigris altaica) and Sumatran tigers (Panthera tigris sumatrae) were analyzed using survival analyses to evaluate return to reproductive status after implant removal or assumed expiration. Females placed in potential breeding situations after MGA implants were surgically removed showed a 62% return to reproduction by 5.25 years, whereas females with implants that were assumed to have expired showed only a 30% return to reproduction by 6 years. Implanted females did not reproduce as successfully as non‐implanted control females, which showed an 85% probability of reproducing after placement in a new breeding situation by 2.66 years. Parturition increased the probability of reproducing in non‐implanted females, but not in implanted females. Litter size, stillbirths, and offspring survival were not significantly different between non‐implanted, implant‐removed and implant‐expired female tigers. Ten female tigers reproduced both before and after implant placement, and the differences in litter size, stillbirths, and offspring survival were not significant, nor were they significantly different from non‐implanted females. Prior parturition, age when implant was removed, and duration of implantation did not affect the probability of reproducing for females after implant removal. These results show substantial reversibility of MGA implants, leading to 62% successful reproduction after implant removal. The reasons for lower successful reproduction in animals previously treated with the contraceptive compared to non‐implanted females are not known, but a greater delay in reversibility was seen when implants were left in place and only presumed expired. Zoo Biol 26:275–288, 2007. © 2007 Wiley‐Liss, Inc.     

Aggression control in a bachelor herd of fringe‐eared oryx (Oryx gazella callotis), with melengestrol acetate: Behavioral and endocrine observations

Aggression control is becoming an important component in the management of animals in captivity, but rigorous quantification of aggressive behavior has heretofore been lacking. This study was done to assess the ability of melengestrol acetate (MGA) given with feed (1.54 mg/kg) to control aggression in a bachelor group of fringe‐eared oryx (Oryx gazella callotis). Systematic behavioral observations were conducted and fecal androgen content was measured for 42 and 90 days, respectively, before treatment, and during the 42 days of treatment. There was a significant reduction in concentrations of fecal androgen from 153 ± 6.0 to 95 ± 4.5 ng/g (T₆₆ = 7, P < 0.0001). This reduction in androgen excretion was apparent after the first week of treatment. There was measurable MGA excreted in the feces during treatment. Although treatment did not arrest all aggressive behaviors among animals, the decline in androgens and increase in MGA was accompanied by a significant reduction in several measures of agonistic behavior. Posturing, aggressive contact, pursuit, and submission occurred significantly less frequently after treatment, and there was also a reduction in fighting‐intention movements. Thus, both ritualized and nonritualized aspects of aggression were affected. Reductions in hormones and aggressive behaviors coincided temporally, suggestive of a potential causal relationship. Consistent with this hypothesis is a strong positive correlation between fecal androgen and total aggressive acts. This effect was not the result of a single behavioral element but occurred across several categories of agonistic behavior. Zoo Biol 20:375–388, 2001. © 2001 Wiley‐Liss, Inc.     

Nomegestrol acetate, a novel progestogen for oral contraception

Nomegestrol acetate (NOMAC) is a potent, highly selective progestogen, which is structurally similar to 19-norprogesterone and characterized as a full agonist at the progesterone receptor, with no or minimal binding to other steroid receptors, including the androgen and glucocorticoid receptors. In animal models, NOMAC demonstrated moderate antiandrogenic activity and strong antiestrogenic activity. In clinical studies, the progestogen was associated with effective suppression of gonadotropic activity and ovulation in premenopausal women, and a neutral impact on hemostasis, lipids, and carbohydrate metabolism. In normal and cancerous human breast tissue, NOMAC has shown favorable effects on estrogen metabolism, and in human breast cancer cell lines in vitro, it does not stimulate cell proliferation. The pharmacologic profile of NOMAC suggested that it would be well suited for combination with a physiologic estrogen in a combined oral contraceptive (COC), with the aim of achieving effective contraception with good cycle control and a favorable safety profile. A monophasic COC containing NOMAC 2.5 mg and 17β-estradiol (E2) 1.5 mg, administered in a 24/4-day regimen, is currently under clinical investigation. In a phase III study, NOMAC/E2 provided consistent and robust ovulation inhibition, with contraceptive effects that compared favorably with those of drospirenone 3 mg/ethinyl estradiol (EE) 30 μg. Investigators for a second phase III study reported less overall impact with NOMAC/E2 on hemostatic, lipid, inflammatory, and carbohydrate metabolism parameters than with levonorgestrel 150 μg/EE 30 μg. These clinical findings are promising; however, full publication of results from the pivotal phase III trials of NOMAC/E2 is pending.     

The effect of contraceptive implants on the behavior of female Rodrigues fruit bats,Pteropus rodricensis

This study investigated the effects of a melengestrol acetate contraceptive implant on the behavior of captive Rodrigues fruit bats (Pteropus rodricensis). Eighteen female bats (nine controls and nine implanted animals) were studied over three 4 week periods: prior to implantation, immediately postimplantation, and 6 months postimplantation. The only significant differences found 6 months postimplantation were that time spent hanging alert decreased in both groups and, concurrently, amount of time spent engaged in other activities, most noticeably social interactions, increased. In connection with this, the number of nearest neighbors increased. However, these changes were seen in all bats and were also associated with the increasing size of the resident colony. There were no significant differences between the two groups of bats in the number of nearest neighbors or sexual partners over the course of the study. The physical effects of the contraceptive implants, increased weight gain and retarded hair regrowth above the incision site, were very clearly shown. There was a 22% rate of rejection/loss of the implants. None of the implanted bats produced offspring postimplantation. This study has shown that melengestrol acetate implants are an effective way to limit reproduction in female Rodrigues fruit bats, at least in the short term, and have no effect on the behavior of this highly social species. © 1996 Wiley-Liss. Inc.     

Efficacy and effects of short- and medium-term contraception in the common marmoset (Callithrix jacchus) using melengestrol acetate implants.

This study examines the effect of melengestrol acetate (MGA) implants on reproductive function and various biochemical parameters, ovarian activity, and uterine morphology in ten female common marmosets implanted for either 6-8 or 19-21 months. Measures of body weight, concentrations of urinary glucose and blood liver enzymes were taken. Ovarian activity was assessed by analysis of urinary progestin levels and ultrasound examinations of the ovaries. Ultrasonography was also used to evaluate uterine morphology. MGA was highly effective in preventing pregnancies in the study animals. No changes in biochemical parameters were found; however, seven females developed a substantial weight gain during the study. Follicular development was not suppressed, as indicated by the presence of antral follicles, luteinized structures, and elevated urinary progestin levels. The uteri of the MGA-treated subjects were moderately enlarged with a thickened endometrium that showed a marked change in structural appearance indicative of hypertrophy and decidualization. After implant removal these changes quickly disappeared and all females ovulated within 3 weeks and conceived within 4 months post-treatment. MGA appears to be an acceptable contraceptive in the marmoset, although non-steroidal methods should be evaluated as possible potential alternatives.     

Immunocontraception of captive exotic species. I. Przewalski's horses (Equus przewalskii) and banteng (Bos javanicus)

A contraceptive vaccine made of porcine zonae pellucidae (PZP) was tested in three Przewalski's mares and five banteng cows. The vaccine antigen consisted of the complete family of glycoproteins of the porcine zona pellucida, including the sperm receptor ZP3. All mares and three of five banteng were inoculated with 2 or 3 i.m. injections of approximately 65 μg of antigen given over a 6 week period. Two other banteng received inoculations of only 35 μg of antigen on the same schedule. Two of the three mares and three of five banteng cows were pregnant at the time of inoculation. No new pregnancies, as a result of postinoculation breedings, occurred among either the mares 36 months after 65 μg antigen inoculations or among the banteng for 24 months after 65 μg inoculations. One postinoculation pregnancy resulted among the two banteng receiving only 35 μg of antigen. Differences in fertility between treated and control mares and between preinoculation and postinoculation reproductive performance of the banteng were significant (P < 0.05). Urinary ovarian steroid metabolites and behavioral observations indicated follicular development and ovulations were occurring among treated mares during the year following PZP inoculations. PZP immunization produced progressively elevated anti-PZP antibodies in both species, which provided contraceptive protection. PZP immunization appears to be an effective form of contraception in both species. © 1995 Wiley-Liss, Inc.     

Retrospective study of morbidity and mortality of captive jaguars (Panthera onca) in North America: 1982–2002

One hundred seventy‐two medical records of captive jaguars (Panthera onca) were examined from 30 American Zoo and Aquarium Association (AZA) institutions housing jaguars between 1982–2002. The study determined common causes of morbidity and mortality, and the influence of age, gender, and melengestrol‐acetate (MGA) exposure on these rates. The most common causes of morbidity in captive jaguars were found to be dental, gastrointestinal, integumentary, and musculoskeletal diseases. Prevalence of types of disease varied with age, with older animals experiencing a higher prevalence of multiple types of disease. Females developed reproductive disease more frequently than males, and the data suggest that MGA exposure increased the risk of developing female reproductive disease. The most common causes of mortality were reproductive diseases in females and musculoskeletal diseases in males. There was a high rate of neonate and pediatric mortality, primarily due to stillbirths or unexplained neonatal death, trauma, and pneumonia. Other diseases or clinical signs that seemed remarkable were a high prevalence of episodes of epistaxis among young, as well as old, jaguars. Based on these findings, management suggestions for the captive jaguar population are presented. Zoo Biol 0:1–12, 2006. © 2006 Wiley‐Liss, Inc.     

Effect of melengestrol acetate on the bovine ovary

Summary To investigate the relation of ovarian morphology to increased body weight gain during administration of melengestrol acetate (17-acetoxy-6-methyl-16-methylenepregna-4,6-diene-3,20-dione, or MGA, a progestagen), ovaries of 100 Holstein dairy heifers were examined for characteristics of follicular maturation, signs of lipid secretion, and the presence of steroid-producing-type cell organelles. The heifers were fed either a normal or a high-protein level ration with or without 0.30–0.45 mg daily of MGA from 2.5 months of age to the age of first estrus or to breeding age (120 cm withers height). The high-level ration effect was not consistently mediated by the special development of ovarian structures. MGA effect, like the weight-gain effect, was consistently evident after the time of first estrus. MGA suppressed estrus and ovulation, and resulted in the presence in the ovary, after regression of corpora lutea, of an increased number of large follicles. The largest follicles corresponding in structure to developing proestrous, mature estrous, or early atretic follicles contained hypertrophied theca interna cells showing lipid secretion signs and ultrastructural characteristics of steroid synthesis. The majority of the largest follicles, however, were atretic or late atretic and did not contain steroid-type cells. The development of replacement follicles was evident in ovaries with late atretic largest follicles. The weight-gain effect of MGA may therefore be associated with a steroidogenic, probably estrogenic, effect in the cow.Dedicated to Prof. W. Bargmann of Kiel.This investigation was supported by scholarships of the Ministère Français des Affaires Étrangères and the Alexander von Humboldt-Stiftung to Dr. J. Priedkalns.Drs. R. G. Zimbelman and L.S. Goyings of the Upjohn Company, Kalamazoo, Michigan, and Drs. D.E. Pritchard, R.W. Purchas, H.A. Tucker, H.D. Hafs, and L.J. Boyd of the Department of Dairy Science, Michigan State University, East Lansing, Michigan, designed and conducted a study on the effects of melengestrol acetate on Holstein heifers and provided ovaries for this investigation. The author wishes to thank Dr. J. W. Lauderdale of the Upjohn Company for aid in statistical analyses; the Department of Veterinary Anatomy, University of Minnesota, St. Paul, Minnesota, and the Laboratoire d'Histologie de l'École Nationale Vétérinaire de Lyon, for assistance in the processing of the ovarian tissues for electron microscopic examination; and the Laboratoire d'Histophysiologie du Collège de France, Paris, for providing facilities for a part of the histochemical study of the ovaries.A brief report of this investigation has been presented to the Société des Sciences Vétérinaires de Lyon (Priedkalns, 1971).     

Habitat associations of four ungulates in mountain forests of southwest China, based on camera trapping and dung counts data

The present study aimed to assess abundance indices and habitat associations of four sympatric ungulate species (alpine musk deer Moschus chrysogaster, tufted deer Elaphodus cephalophus, Chinese serow Capricornis milneedwardsii, and Chinese goral Naemorhedus griseus) in Baima Xueshan Nature Reserve of southwest China, using camera trapping and dung counts data. Camera traps were set along six dung transects in different habitats and explored habitat use of the sympatric ungulates using trapping rates. The results obtained revealed that Chinese serow showed a negative association with open canopy cover and low canopy cover. Alpine musk deer were associated with oak shrubs, oak forests and open canopy cover, while tufted deer avoided oak shrubs. Goral showed no significant associations with habitat variables. Alpine musk deer and tufted deer had considerable habitat overlap with Chinese serow. By finding a high correlation between indices, the study indicates that camera trapping may represent a valid index of relative abundance, matching results from other studies.     

Immunocontraception of captive exotic species. III. Contraception and population management of fallow deer (Cervus dama)

Immunocontraception has become an increasingly valuable tool in the population management of captive exotic ungulates. Although porcine zona pellucida vaccine (PZP) was used successfully in other cervids, a previous study with fallow deer (Cervus dama) suggested that the vaccine did not work in this species. In the current study, PZP was tested in two captive herds of fallow deer. Antibody titers were monitored over a 3‐year period to evaluate three different adjuvant protocols, and the vaccine was applied to an entire herd to determine the impact on fawning rates. In a semi‐free‐ranging herd, antibody titers rose from preimmunization levels of 2.6% of positive control serum to 56.5% 4 weeks after initial inoculations, to 65.1% at 1 year, and to 81.3% at 2 years, after a single annual booster was applied. Fawn production in this herd was reduced significantly over 3 years. The adjuvant protocol of Freund's Modified Adjuvant® (FMA) for the initial inoculation followed by a booster with Freund's Incomplete Adjuvant® (FIA), and the protocol of FMA for the initial inoculation followed in 3 weeks by a booster with FMA both produced significantly higher antibody titers than the 3× FIA (3 weeks apart) protocol after year 1. The FMA+FMA protocol produced significantly higher titers than the 3× FIA protocol at year 2, but was not different from the titers produced by the FMA+FIA protocol at year 2. Zoo Biol 22:261–268, 2003. © 2003 Wiley‐Liss, Inc.     

Impact of female contraception for population management on behavior and social interactions in a captive troop of Guinea baboons (Papio papio)

As part of a population management strategy for a troop of Guinea baboons (Papio papio) at Yorkshire Wildlife Park, adult females were given a Suprelorin contraceptive implant. There was no information on the effect of contraception on behavior in this species, so behavioral data were collected before and after implant placement to determine any impact on the troops’ welfare. Social interactions, affiliative, agonistic, and self-directed displacement behaviors (SDBs) in all adults were monitored via focal sampling. Preimplant data were collected in August/September 2019 before Suprelorin placement on November 2019, and postimplant data were collected in August/September 2020, allowing for comparison while controlling for seasonal differences in behavior. We found a significant reduction of SDBs after intervention, suggesting that contraception has a positive impact on group welfare, as SDBs are key behavioral indicators of stress and anxiety in nonhuman primates. Additionally, the rate of substate change per hour (i.e., the number of times the baboon changed their behavior), duration of sentry behavior, and the frequency of agonistic bouts were significantly lower postimplant, further suggesting improvements in welfare. There were also no significant decreases in the duration of positive social interactions, such as allogrooming and play. The results show that Suprelorin did not have a detrimental impact on the behavior of adults in the troop and may have even improved welfare. The use of Suprelorin in females could be considered as an effective population management strategy for primates existing in similar social systems.     

Use of intrauterine devices (IUDs) for contraception in the common chimpanzee (Pan troglodytes)

The common chimpanzee (Pan troglodytes) is a species phylogenetically very close to man. It was not many years ago that the captive population of chimpanzees (P. troglodytes) was considered at risk because of perceived problems with reproductive success. With the potential need for many individuals for research in a variety of areas, particularly in the areas of parasitic and viral infections, an NIH-funded program was established to promote the breeding of the species. That program, the 'National Chimpanzee Breeding and Research Program', was highly successful, so successful, in fact, that there is now a surplus of animals available for current research programs. This situation has prompted the use of intrauterine devices (IUDs) as a method of fertility control. Overall, this method is successful and associated with a failure (of pregnancy) rate similar to that reported in the human. Physical and logistic constraints, however, render the method less than ideal for situations where a pregnancy rate of zero is desired.     

Correlation of relative muzzle width and relative incisor width with dietary preference in ungulates

Qualitative observations suggest that grazing ungulates have relatively broader muzzles than browsing ones, and that grazers have incisors that are all of a similar size, as opposed to the large central and smaller lateral incisors seen in browsers. These differences may be correlated respectively with the need for grazing ungulates to maintain a large daily intake, or for browsing ungulates to forage selectively in a stand of vegetation. Quantitative examination of relative muzzle width and incisor width ratio in 95 species of living ungulates, correlated with seven different types of dietary preferences, substantiated these observations, although phylogenetic history may exhort a strong influence on morphological proportions. For example, equids have relatively narrower muzzles than grazing ruminants despite their less selective mode of feeding. The narrowest relative muzzle widths are not found in regular browsers, but in high level browsers and in mixed feeders in open habitats. Incisor width ratio can distinguish grazers from browsers, but can not be used to discriminate mixed feeders from other feeding types, and grazers appear to have incisors that are relatively broader overall than those of other dietary types, in correlation with their relatively broader muzzles.     

Monitoring ungulates in steep non-forest habitat: a comparison of faecal pellet and helicopter counts

Faecal pellet counts have been widely used to monitor the abundances of introduced ungulates in New Zealand, but ground-based sampling cannot be conducted safely in the steep non-forest habitats that are common in New Zealand's Southern Alps. Helicopter counts may be an effective technique for monitoring ungulates in steep non-forest habitat. We evaluated the relationship between faecal pellet and helicopter counts of ungulates (primarily feral goat Capra hircus) at 12 non-forest sites in the Southern Alps. Within each site we counted the numbers of ungulates from a helicopter on three occasions and the number of intact faecal pellets along 30 transects. Mean observed densities of feral goats derived from helicopter counts ranged from 0.0 to 20.2 km^?2. There was a positive curvilinear (concave down) relationship between faecal pellet and helicopter counts. Compared with faecal pellet counts, helicopter counts were cheaper, could identify ungulate species and provided estimates of absolute density. Helicopter counts are a cost-effective method for monitoring ungulates in the steep non-forest habitats of New Zealand's Southern Alps.     

Review of contraception in ungulate species

Most ungulate species are herd animals. In captivity, and increasingly so in the wild, space constraints limit natural behaviors associated with group dynamics, possibly resulting in inbreeding and/or overpopulation. This situation has necessitated research regarding contraception of various species of hoofstock. Differing management situations mandate different contraception protocols to achieve optimal results. Fertility control in hoofstock has been achieved through a number of different contraceptive methods predominantly surgical sterilization, mechanical contraception, synthetic steroid hormones, and immunocontraception. In this study successes and limitations of these techniques are reviewed. Zoo Biol 26:311–326, 2007. © 2007 Wiley‐Liss, Inc.     

A standard set of polymorphic microsatellites for threatened mountain ungulates (Caprini,Artiodactyla)

Nearly 70% of the world's mountain ungulate taxa are endangered. The availability of a standard set of DNA markers for forensic and molecular ecology studies would help to establish conservation programs and detect poaching activities of these endangered taxa. We tested 60 published microsatellite primer pairs from bovids (cattle, sheep and goat) on 49 individuals from 11 taxa including six wild goat‐like species (Capra spp.), three divergent wild sheep (Ovis spp.), and two chamois (Rupicapra spp.) species. Approximately 30 microsatellites amplified a microsatellite‐like PCR product in all three genera, and with the exception of ILST097, nearly all the loci were polymorphic within most of the 11 species.     

Low invasive estrous synchronization protocol for wild animals: an example with melengestrol acetate in brown brocket deer (Mazama gouazoubira)

Deer are sensitive to stressful stimuli by handling and their reproductive physiology could be altered by these procedures, making it necessary to develop less invasive protocols for ART. Melengestrol acetate (MGA), a synthetic progestin administered orally, appears as an alternative for estrous synchronization protocols (ESP), such as reported in cattle. Firstly, we compared two MGA doses (0.5 and 1.0 mg/day/animal), which would have suppression effect in estrous behavior (EB). Eight females were randomly and equally distributed in Group 1 (G1) and Group 2 (G2), which received 0.5 and 1.0 mg/day/animal respectively for 15 days (D1 to D15). Two cloprostenol (CP) applications were performed on D0 and D11. Estrus detection (ED) was performed every day. All females from G1 displayed estrus during treatment period, whereas all females from G2 displayed estrus after treatment, suggesting a suppressive effect of 1.0 mg in the EB. Once the suppressive MGA dose (1.0 mg) was defined, we used this dose for assessing ESP. The same eight females received 1.0 mg/animal for eight days (D-8 to D-1), followed by 0.25 mg of estradiol benzoate on D-8 and 265 μg of CP on D0. Feces for fecal progesterone metabolites (FPM) measurement were collected from D0 until seven days after the last day of estrus. Seven females displayed estrus between 12 and 72 h after CP application, which was followed by a significant increase in FPM levels (except female MG6), suggesting the formation of corpus luteum. After ED, females were placed with a fertile male to assess the fertility of the protocol. Pregnancy was confirmed by ultrasound 30 days after mating in 3/6 individuals. Although the low effectiveness of MGA protocol, it should be considered as a promising alternative in deer ESP since this protocol has less stressful effect on the animal during reproductive management when compared to other ESP.