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Testosterone Levels in Male Formosan Reeve , s Muntjac: Uncoupling of the Reproductive and Antler Cycles
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Kurtis Jai-Chyi Pei, Kerry Foresman, Bing-Tsan Liu, Long-Hwa Hong, and John Yuh-Lin Yu (2009) Testosterone levels in male Formosan Reeve's muntjac: uncoupling of the reproductive and antler cycles. Zoological Studies 48(1): 120-124. Cervid species are generally assumed to be seasonal in their reproductive activity, and species that develop antlers also do so in a seasonal manner in conjunction with this annual puberty. As gonadotropin endocrine support for reproductive activity wanes, the resultant lowered testosterone levels initiate antler casting. Male Formosan Reeve's muntjac (Muntiacus reeves micrurus) exhibits an annular antler cycle with growth initiating in early May, velvet shedding and antler hardening by early Sept., and casting the following May. This cycle was correlated with fluctuating testosterone levels in a manner somewhat similar to that observed in other cervids. However, this species remains reproductively active year-round with spermatozoa present in the testes and epididymides, with no variation in their quantity or quality. These findings suggest that the testosterone threshold required for antler development in this muntjac may be set higher than that required for spermatogenesis, or conversely, that spermatogenesis might be controlled by other hormones in addition to testosterone. http://zoolstud.sinica.edu.tw/Journals/48.1/120.pdf.
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... Male muntjacs (genus Muntiacus), however, despite demonstrating a regular annual testosterone and antler replacement cycle like other deer species, do not exhibit the annual repuberty phenomenon and remain fertile throughout the year, even when they are in the velvet period, which occurs from the beginning of antler regrowth until it is mineralized and cleaned [15][16][17][18][19][20][21]. As a result, births can occur every month of the year [22][23][24][25][26][27]. ...
... Nevertheless, the high amount of, or even no reduction in, testosterone production during the velvet period, which is featured in the study, was not expected because our previous study did show significant annual fluctuations in the fecal testosterone level in male muntjac [17]. The concentration and number of Leydig cells used in this in vitro study were the same for all treatments; therefore, a possible explanation is that although the function of producing testosterone by the muntjac Leydig cell does not regress during the velvet period, the number of Leydig cells might decrease significantly, which caused the decrease in concentrations of fecal testosterone of muntjac during the velvet period compared with in the hard-antlered stage [17]. ...
... Nevertheless, the high amount of, or even no reduction in, testosterone production during the velvet period, which is featured in the study, was not expected because our previous study did show significant annual fluctuations in the fecal testosterone level in male muntjac [17]. The concentration and number of Leydig cells used in this in vitro study were the same for all treatments; therefore, a possible explanation is that although the function of producing testosterone by the muntjac Leydig cell does not regress during the velvet period, the number of Leydig cells might decrease significantly, which caused the decrease in concentrations of fecal testosterone of muntjac during the velvet period compared with in the hard-antlered stage [17]. It has been shown that the intratesticular testosterone level was significantly related to the number of Leydig cells and the concentration of Leydig cells per testis was 53% greater during the breeding season in stallions [30]. ...
Previous studies have shown that despite having a clear seasonal fluctuation in fecal testosterone concentration, the significantly lower testosterone levels found in velvet stags of the nonseasonal breeder muntjac (Muntiacus sp.) apparently did not stop their spermatogenesis as in other deer species. In the present study, in vitro cultivated Leydig cells isolated from adult stags of three native deer species of Taiwan were treated with androstenedione, with or without adding human chorionic gonadotropin. Results showed that, unlike the two seasonal breeders, sika deer (Cervus nippon) and sambar deer (Rusa unicolor), Leydig cells of velvet muntjac had no dramatic reduction in or even maintained the full capability of their testosterone productivity compared with the hard-antlered stage. The decrease in fecal testosterone level observed earlier in muntjac during the velvet period was probably due to a reduction of number of Leydig cells. These results support the hypothesis that testosterone production in muntjac during its velvet period might never be low enough to trigger the quiescent phase of the reproduction cycle.
... Tahapan pertumbuhan ranggah juga telah dilaporkan pada rusa timor jantan, yang memperlihatkan adanya hubungan antara aktivitas reproduksi dan pertumbuhan ranggahnya (Handarini, 2006). Namun demikian, pola reproduksi seperti yang ditemukan pada beberapa spesies rusa tersebut sedikit berbeda bila diamati pada formosan muntjak (Pei et al., 2009), dan muncak Indonesia (Wahyuni, 2012). Aktivitas reproduksi pada kedua spesies muncak tersebut tetap berlangsung pada ketiga tahap ranggah. ...
The objective of this study was to investigate the pattern of carbohydrate distribution of accressory sex glands in male muntjac (Muntiacus muntjak muntjak) in the velvet antler stage. In macroanatomy observation, muntjac accessory sex glands consist of the ampulla, vesicular gland, pars diseminate prostat, and bulbourethral gland. The observation of neutral carbohydrate distribution has done by periodic acid Schiff (PAS) staining. In addition, acid carbohydrate was observed by using alcian blue (AB) pH2,5 staining. Result of this research showed that neutral and acid carbohydrate scattering in each accessories sex gland with different pattern. Neutral carbohydrate with medium (++) and high (+++) intensity reaction was found in the ampulla, vesicularis gland, and bulbourethral gland and strong in prostat gland. The acid carbohydrate with low (+) and medium (++) intensity reaction was observed in the ampulla, low in vesicularis gland, and negative in prostat and bulbourethral glands. In conclusion, the neutral carbohydrate was found dominantly on surface of all accessory sex glands of male muntjac in velvet antler stage with highest concentration and intensity of colour in prostat gland.Key words: carbohydrate, accessory sex glands, muntjac (Muntiacus muntjak muntjak)
... m. reevesi) [39], Formosan muntjac (M. reevesi micrurus) [40], and brown brocket bucks (Mazama gouazoubira) [3]. We propose that the Javan muntjac follows a similar reproductive pattern as those cervids in the context that the complete eight stages of seminiferous epithelium observed in the hard antler period are also found in the velvet antler period. ...
Stages of the seminiferous epithelium of the testis of the wild Javan muntjac ( Muntiacus muntjak muntjak ) in hard antler period were characterized based on the tubular morphology method. The number and the relative frequencies of seminiferous epithelium stages and the morphometry of germinal cell nuclei were identified microscopically. We identified eight stages of seminiferous epithelium in testicular tissue of the Javan muntjac and found that the relative frequencies of stages I to VIII were 14.87, 15.12, 17.75, 6.87, 7.37, 12.37, 13, and 12.62%, respectively. The diameter of the nuclei of germinal cells varied in each stage of seminiferous epithelium. Diplotene-stage primary spermatocytes had prominent and large nuclei ~8.97 ± 1.0 μ m in stages III and IV. Pachytene primary spermatocytes appeared in most stages, except stage IV, whereas leptotene- and diplotene-stage primary spermatocytes were found in stages I and II, and III and IV, respectively. Round spermatids were observed in stages IV to VIII and in stage I but were absent in stages II and III, while elongated spermatids were observed in all stages except stage I. Our findings show that the stages of seminiferous epithelium in the Javan muntjac are similar to those found in neotropical cervids, small ruminants, and other domestic animals.
... reevesi) and formosan muntjak (M. m. micrurus) are also aseasonal but then they reproductive activities still taken place although they are in casting and velvet periods (Chapman and Harris 1991;Pei et al. 2009). ...
Muntjak (Muntiacus muntjak muntjak) belongs to Cervidae family which distributed in Java Island and Southern part of Sumatera. This cervid has been protected by Indonesian Government since 1999. In order to support breeding program of the species and to avoid them from extinction, its reproductive biology such as spermatogenesis and the correlation to semen quality is important to be investigated. Therefore, the objective of this study was to examine spermatogenesis and semen quality of two adult male muntjaks during antler growth periods that consist of hard antler (H), casting (C), and velvet antler (V). Testicular tissues and semen (ejaculates) were obtained by core needle biopsy and electroejaculation methods respectively. Testicular tissues were processed histologically and stained with periodic acid Schiff (PAS) to observe spermatogenesis whereas semen was evaluated to obtaine its quality. The results showed that spermatogenic activities were detected in all antler periods which marked by PAS positive staining (magenta colour) of round and elongated spermatid acrosomes. In H period, spermatogenic activity was higher than those C and V periods. According to semen evaluation, motile spermatozoa were found with different concentration in all antler periods. The highest sperm concentration (x 10 6 spermatozoa/ml) in both of muntjaks was found in H period (506.25 ± 61.87), and slightly decreased in C (288.75 ± 37.12), and V periods (362.60 ± 17.68). These finding showed that spermatogenesis to produce spermatozoa is taken place while muntjaks are in C and V periods with differ activities that provable with the existence of motile spermatozoa from ejaculates in both of male muntjaks. Therefore, muntjaks could provide reproductive function throughout the year of reproductive aseasonality which is similar to the reeves and formosan muntjaks.
... Satwa ini merupakan satwa yang dilindungi pemerintah, seperti yang tercantum dalam Daftar Lampiran Peraturan Pemerintah Republik Indonesia Nomor 7 Tahun 1999 sejak tanggal 27 Januari 1999 (PHKA, 2004). Sejauh ini informasi tentang biologi reproduksi muncak khususnya tentang karakteristik dan Muncak (Muntiacus muntjak) dikenal pertumbuhan ranggah velvet masih terbatas tentang karakteristik dan pertumbuhan ranggah velvet masih terbatas pada spesies Muntiacus reveesi (Chapman dan Harris, 1991) dan Muntiacus reveesi micrurus (Pei et al., 2009) serta beberapa spesies Cervidae, seperti rusa timor (Cervus timorensis) (Semiadi, 1997;Handarini et al., 2004), rusa bawean (Axis kuhlii) (Semiadi et al., 2003) dan red deer (Cervus elaphus) (Li et al., 2003). Sejauh ini data tentang biologi reproduksi muncak (Muntiacus muntjak muntjak) Indonesia belum pernah dilaporkan. ...
Penelitian ini bertujuan menggambarkan morfologi pertumbuhan ranggah velvet (RV) dua ekor muncak jantan (M1 dan M2) yang dipelihara di kandang penelitian secara terpisah. Tanggal lepas ranggah dan hari pertama percabangan RV serta awal pengelupasan kulit velvet diamati dan dicatat. Pengukuran meliputi panjang dan diameter ranggah velvet utama (RVU) dan ranggah velvet cabang (RVC) dexter et sinister, serta durasi pertumbuhan RV. Rataan ± SD panjang dan diameter maksimum RVU dan RVC muncak M1 adalah 148,25±1,12 mm; 46,26±0,68 mm (panjang), 19,21±2,35 mm; 9,12±0,21 mm (diameter) dengan durasi pertumbuhan 104 hari; sedangkan muncak M2 berturut-turut adalah: 146,44±1,58 mm; 46,94±1,97 mm (panjang); 13,65±1,27 mm; 8,49±0,29 mm (diameter) dengan durasi pertumbuhan 98 hari. Tidak terdapat perbedaan tahapan pertumbuhan RVU dan RVC antara muncak M2 dan M1, namun berbeda pada ukuran RV dan durasi pertumbuhannya. Muncak M2 memasuki ranggah keras setelah pengelupasan kulit velvet lebih cepat dibandingkan M1. Dapat disimpulkan bahwa ukuran pertumbuhan RV berkorelasi erat dengan faktor umur, berat badan, dan postur tubuh muncak jantan.
... Bilateral synchrony, or at least close succession, in loss of antlers is to be expected because the process occurs in response to a fall in testosterone levels (Bubenik 1982), even in the special case of muntjac (Pei et al. 2009) in which the males remain fertile during the growth of the next pair of antlers (Chapman et al. 1997). Sheng (1991) reported two examples of casting by captive Reeves' muntjac in China as 14 and 16 June and 6 and 8 May respectively. ...
From 1973 until the present time, captive Reeves’ muntjac (Muntiacus reevesi) have been observed in England. The dates of casting of both antlers have been recorded for 25 bucks, totalling 121 antler cycles. All casting dates were between 1 May and 17 July (63.64 % of the cycles occurred in May, 34.71 % in June, and only 1.65 % in July). Only 13.2 % of the antler cycles were synchronous. In 45.71 % of cases, the left antler was cast 1 day or more before the right one, whereas in 54.29 % of cases, the reverse was true. For 57.14 % of cases, the time between castings of the first and second antlers was up to 3 days, and for 32.38 % of the cases, the interval was 4 to 8 days, and in 10.48 %, the difference was 9 to 13 days. All bucks cast their antlers asynchronously at least in some of the antler cycles. No external factor, which would be responsible for this, was detected. Significant variation across season has been shown with no apparent trend. Although records on subsequent seasons were available for most of the bucks, there was a zero repeatability of the process.
... The finding in the present study that the highest level of plasma testosterone occurred during the rut period (July/August) is consistent with the results of numerous studies by other authors confirming that the highest level of this hormone occurs during the female rut period (Blottner et al., 1996;Roelants et al., 2002;Göritz et al., 2003). Circannual changes in the testosterone level and the occurrence of the highest concentration of this hormone during the rut period were also noted for other males of the family Cervidae (Whitehead and McEwan, 1973;Mirarchi et al., 1978;Barrell et al., 1985;Asher and Peterson, 1991;Monfort et al., 1993;Bubenik et al., 1996;Yamauchi et al., 1997;Chunwang et al., 2001;Pei et al., 2009). Testosterone in sexually mature males is responsible for the maintenance of the process of spermatogenesis, the maturation of sperm in the epididymis, the development and maintenance of secondary sexual characteristics, and the appearance of sexual behaviour (Anahara et al., 2008). ...
The roe deer (Capreolus capreolus) is a seasonally breeding species. The regression of the gonads and the inhibition of the process of spermatogenesis during the winter, the regeneration of the gonads during the spring and the occurrence of the highest level of spermatogenesis during the summer are observed in mature males. A radioimmunological analysis of the steroid hormone levels in the peripheral blood of male roe deer, measured at the beginning (May), at the peak (July/August) and at the end (September) of the reproductive season, demonstrated that the highest levels of progesterone, androstenedione, testosterone, and oestradiol coincided with the peak of reproductive activity. In addition, an immunohistochemical localisation of androgen receptors (AR) in the testis and epididymis during the same study periods showed that the highest immunoreactivity of the target cells occurred at the peak of the reproductive season (July/August). The results of the study indicate that all of the sex hormones (not only testosterone) may play a significant role in the regulation of reproductive processes. Increasing levels of steroid hormones (especially the androgens) induce the expression of androgen receptors in the target cells of the testis and epididymis, ensuring their normal function and maintenance.
... Also in chital, breeding activities might be triggered by increasing day length and hormone levels. However, some deer species in the tropics, although experiencing individual annual rutting periods, show very weak or no synchronization in antler cycle with environmental variables (Schaller 1967; Goss 1963, 1969; Lincoln 1985; Pei et al. 2009). In the case of sambar, we observed a strong effect of decreasing day length. ...
Antler cycles are convenient external signs indicating internal changes in reproductive status of male deer. Antler phenology of chital (Axis axis) and sambar (Rusa unicolor) were studied in a deciduous habitat of Mudumalai Tiger Reserve, Western Ghats, using vehicle transects for 2 successive years. Apparent breeding seasonality occurred with the majority of adult stags in hard antlers from May to mid October in chital (>87 %), and October to May in sambar (>68 %). Adult hard antler in chital correlated with mean group size, while sambar showed a weak correlation between adult hard antler and group size. Chitals prefer forming large groups at forest edges and open habitats while sambars prefer dense vegetation cover. Adult hard antlers in chital and sambar showed a weak relation to fawning since most adult females were in oestrus during the peak rutting season. Adult hard antlers in chital associated positively with rainfall and day length while sambar responded weakly to rainfall. We conclude that environmental variables determined species-specific mating strategies in the two deer species.
This book contains 19 chapters that discuss theoretical and applied andrology for domestic, zoo and wild animals. Topics include semen and its constituents; sperm production and harvest; determinants of sperm morphology; sperm preparation for fertilization; practical aspects of semen cryopreservation; evaluation of semen in the andrology laboratory; genetic aspects of male reproduction; emerging techniques and future development of semen evaluation and handling and applied andrology in cats, dogs, fowls, turkeys, sheep, goats, cervids, horses, cattle, zebu, buffaloes, pigs, camelids, zoo animals and wild animals. It will be of use for those teaching animal physiology at a tertiary level and a reference for those interested in male animal reproductive evaluation, performance and in semen evaluation, handling and use for artificial breeding.
Timor deer (Rusa timorensis) is a newly domesticated animal in Indonesia and other countries in the world. It is a potential source of meat and livelihood. Low birth rate is a problem of deer farming in Indonesia. It happens because of low concern for key aspects of behaviors including reproductive behavior. The aim of this review is to give information about reproductive behavior of Timor deer in natural habitat and captivity breeding. Libido and estrous behaviors of Timor deer in captivity breeding were similar with natural habitat. However, male Timor deer in captivity breeding took longer time to approach the females before mating, compared with those in their natural habitat. Aggressive behavior commonly leads mating. Parturition and maternal behavior of hinds are affected by limitation of space, therefore dividing the area of cage which depends on age and physiological status is needed to improve reproductive management.
Deer are long-lived herbivores, and most species are seasonal breeders. In females, the most energy-demanding phase of the reproductive cycle (late pregnancy and lactation) is timed to coincide with the period of maximum food abundance and quality. In males, the period of fertility is timed to the availability of estrous females. The annual cycle in gonadal activity is generated endogenously and is entrained to a particular time of year by responses to environmental cues; these are principally changes in day length in the cold/temperate zones, and possibly nutrition in the tropics.
The antlers are one of the secondary sexual characters of males in all genera of Cervidae except Rangifer (where antlers are found in both sexes). Their development, seasonal renewal, maturation, and casting are closely related to the activity of the reproductive system. This fact was already well known to Aristotle, who described the alterations of antlerogenesis caused by castration (Goss 1968). However, it took another 2,000 years before progress in chemistry and endocrinology made it possible to investigate the detail roles of various humoral factors in the regulation of the antler cycle.
Deer native to temperate zones grow new antlers each year in synchrony with the annual photoperiodic cycle. When the amplitude of this cycle is reduced from normal winter and summer solstices (at 42° latitude) of nine and fifteen hours to as little as eleven and one-half and twelve and one-half hours (equivalent to about 9° latitude), sika deer still tend to grow antlers on schedule, even when that schedule is accelerated.
Deer exposed to days of constant length for prolonged periods of time fail to replace their antlers when the light:dark ratio is 12L/12D. When held on unchanging short (8L/16D) or long (16/8D; 24L/OD) days, however, they continue with their antler cycles at irregular intervals averaging about 85% of the siderial year.
These results are interpreted in terms of an inherent circannian rhythm, the duration of which can be adapted to the frequency of the prevailing photoperiodicity, but which reverts to approximately a year on constant long or short days and disappears altogether on simulated equatorial photoperiods.