Antler Casting Research Articles

Relationship between dominance and antler cycle in white-tailed deerOdocoileus virginianus

We tested the hypothesis that there is a negative correlation between rank and order of casting antlers in white-tailed deerOdocoileus virginianus (Zimmermann, 1780) and that dominant individuals will start antler regrowth and velvet shedding earlier than subordinates. We assessed dominance relationship among 14 bucks (1.5 to 7.5 years-of-age) confined in a 0.6 ha enclosure and related hierarchal position to timing of antler casting, initiation of antler regrowth, and initiation of velvet shedding. During 66 observation sessions we recorded 2833 agonistic interactions. Bucks developed an unstable hierarchy with relatively frequent changes in rank, particularly in the upper half of the hierarchy. Antler casting dates were positively correlated with age and wins and losses of agonistic encounters; correlations with body mass approached significance. When age was eliminated as a confounding factor by partial correlation, no significant relationship between antler casting date and other characteristics occurred, except losses. When body mass was eliminated by partial correlation, the relationship between casting date and losses was more pronounced. Timing of antler regrowth was negatively correlated with age, body mass, rank and wins, while positively correlated with losses. The start of velvet shedding was negatively correlated with rank position. Our results are in apparent contrast with previous studies. However, our experimental group contained more individuals in a confined area than is typical for the species. Whitetails may be more susceptible to social stress in captivity than more gregarious species such as red deer, resulting in variable responses to rank position.

Seasonal changes in fecal testosterone concentrations and their relationship to the reproductive behavior, antler cycle and grouping patterns in free-ranging male Pampas deer ( Ozotoceros bezoarticus bezoarticus)

The purpose of this study was to validate noninvasive endocrine monitoring techniques for Pampas deer and to evaluate seasonal changes in testicular steroidogenic activity and their correlation to reproductive behavior, antler cycle and group size. Thus, fecal samples, behavioral data and observations of antler status were collected at monthly intervals during 1 year from free-ranging Pampas deer stags (three radio-collared individuals and 15 random individuals) living in Emas National Park, Brazil (18°S latitude). Fecal steroids were extracted using 80% methanol and steroid concentrations were quantified by a commercial enzyme immunoassay (EIA). Fecal testosterone concentrations peaked in December–January (summer), March (early autumn) and in August–September (winter–spring), with minimal values from April–July. Reproductive behavior had two peaks, the first in December–January, characterized by predominately anogenital sniffing, flehmen, urine sniffing, chasing and mounting behavior, and the second peak in July–September (behavior primarily related to gland marking). There were significant correlations between fecal testosterone and reproductive behavior ( r = 0.490), and between fecal testosterone and antler phases ( r = 0.239). Antler casting and regrowth occurred under low testosterone concentrations, whereas velvet shedding was associated with high concentrations of testosterone. We inferred that Pampas deer stags exhibited a seasonal cycle that modulated sexual behavior and the antler cycle, and we concluded that fecal steroid analysis was a practical and reliable non-invasive method for the evaluation of the endocrine status of free-ranging Pampas deer.

Histological structure of antlers in castrated male fallow deer (Dama dama)

Antlers are periodically replaced cranial appendages that, except for the reindeer, are grown only by male deer. The annual antler cycle is controlled by seasonal fluctuations of sex steroid concentrations in the blood, and accordingly castration of male deer causes deviations from normal antler growth. The present study investigated antler histology of castrated fallow bucks (Dama dama). Castration in early spring was followed by casting of the hard antlers carried by the bucks and the growth of a new set of antlers, which remained in velvet permanently. In the following year, numerous bony protuberances developed from the original antler surface. Further growth of these protuberances, which were formed by subperiosteal intramembranous ossification, led to a marked increase in antler diameter in the affected areas. Compared to antlers of intact bucks, the antlers of the castrates showed histological signs of immaturity, suggestive of a reduced bone remodeling and an impairment of the mineralization process. These changes point to the dependence of the above processes on a stimulation by higher levels of sex steroids. Two years after castration, the antlers also developed integumental thickening and showed an initial formation of skin outgrowths. Cystic structures were present in the skin, which were often filled with a presumably sebaceous and/or keratinous material. Formation of intradermal bone or cartilage was not observed in the antlers of the castrated fallow bucks. The histological structure of the skin outgrowths suggested that they were caused by a hypertrophy of the dermal component of the velvet. Due to the localized bone overgrowth, resulting from the periosteal bone apposition onto the original antler surface, skin-lined infoldings originated, which reached deep into the newly formed bone. Our study revealed no indication of invasive/destructive bone growth in the antlers, i.e., of a penetration of the newly formed bone tissue into the pre-existing bone. The hypertrophic bone growth in the antlers of the castrates is compared with other forms of periosteally derived hypertrophic bone formation, including osteomas, in the mammalian skeleton. It is discussed whether the skin and bone outgrowths of the antlers of castrated fallow bucks may be classified as benign tumors.

Pedicle and antler fusion and double-head formation in a sika stag (Cervus nippon)

A case of pedicle and antler abnormality in a 12–14 year old sika stag shot in January 2003 in Schleswig-Holstein (Germany) is presented. The abnormality combines fusion of pedicles and antler bases with subsequent double-head formation. Double-heads result from growth of new antler bone without casting of the previous hard antlers. In consequence, two consecutively formed antlers are present in an individual. The stag’s skull showed a plate-like osseous structure whose broad and slightly elevated central portion was identified as the fused pedicles. The peripheral parts of this osseous plate constituted the second antler growth of the (former) double-head. A cast pair of antlers, which were fused at their bases, had been found in a neighbouring hunting district in the summer of 2002. The close fit between the casting surface of the fused antlers and the surface of the pedicle/antler structure on the stag’s skull indicated that the antlers had been grown by this stag and were belatedly cast from his fused pedicles. The fused antlers thus constituted the first antler growth of the double-head. We suppose that the broad connection between the fused antlers and the fused pedicles prevented antler casting at the normal time and thereby caused the double-head condition. The presentation of this antler abnormality is taken as an occasion to discuss the significance of pedicles for the normal casting and regeneration of antlers.

사료의 단백질 수준이 Red Deer(Cervus elaphus)의 녹용생산에 미치는 영향

본 연구는 급여사료의 단백질 수준과 고단백질 사료의 급여시기가 레드디어의 녹용생산성에 미치는 영향을 검토하기 위해 급여사료의 단백질 수준을 13%(LL구)와 19%(HH구)로 달리하였으며 또한 단백질 함량 19%의 사료 급여시기를 각각 낙각 전(HH구)과 낙각 시점(LH구)으로 달리하여 사양실험을 실시했다. 녹용의 주간 둘레는 상대, 중대 및 하대 부위의 둘레를 합산한 평균치로서 1998년과 1999년의 실험 모두 HH구에서 가장 높았으나 나머지 두 처리구와의 사이에 유의적인 차이는 인정되지 않았다(P>0.05). 녹용의 주간 길이 역시 2년간의 실험에서 모두 HH구가 가장 길었고 LH구가 가장 짧았으나 유의성(P>0.05)은 인정되지 않았다. 급여사료의 단백질 수준에 따른 처리간의 차이는 인정되지 않았으나 녹용의 주간 둘레와 길이는 각각 녹용생산에 밀접한(P<0.01) 관계가 있는 것으로 분석되었다. 녹용생산성에 있어서는 1998년의 경우 HH구가 평균 2,600<TEX>$\pm$</TEX>1,000g으로서 가장 높았고 LH구가 2,287<TEX>$\pm$</TEX>826g으로 가장 낮은 생산성을 나타냈으나 처리간의 유의성(P>0.05)은 인정되지 않았다. 1999년의 실험에서도 HH구가 평균 3,038 <TEX>$\pm$</TEX>867g으로 가장 높은 생산성을 보였으며 LH구가 2,739<TEX>$\pm$</TEX>1,079g으로 가장 낮은 생산성을 나타냈으나 역시 처리간에 유의성은 인정되지 않았다. 일당 녹용생산량은 1998년의 경우 HH구가 43<TEX>$\pm$</TEX>16g으로 가장 높았고 LH구가 38<TEX>$\pm$</TEX>15g으로 가장 낮았으나 처리간의 유의성은 인정되지 않았다. 또한 1999년의 실험에서도 같은 경향이 나타났다. Three dietary treatments were compared over two years to determine the effects of dietary protein levels and feeding patterns on velvet production in red deer (Cervus elaphus). The LL group received a 13% protein diet whereas the HH group received a 19% protein diet. The LH group switched from the low to high protein diet at the time of antler casting. Significant relationships were found between velvet production and the girth and length of main beam (p<0.01), daily growth rate of velvet (p<0.01), body weight at cutting time (p<0.05 in 1998 and p<0.01 in 1999), date of casting (p<0.01), and body weight and velvet production of the previous year (p<0.05 in 1998 and p<0.01 in 1999). Different levels of protein in diets in this study did not show statistically significant different effects in general. The girth of velvet, summed for top, middle and bottom of the main beam, tended to be thickest in HH for two years and thinnest in LL for 1998 and in LH for 1999. The main beam tended to be longest in HH at 46.3cm in 1998 and 45.2cm in 1999 and shortest in LH at 39.9cm in 1998 and 41.5cm in 1999. Velvet fresh weight tended to be highest in HH at 2,600<TEX>$\pm$</TEX>1,000g in 1998 and 3,038<TEX>$\pm$</TEX>867g in 1999 and lowest in LH at 2,287<TEX>$\pm$</TEX>826g in 1998 and 2,739<TEX>$\pm$</TEX>1,079g in 1999. Daily growth rate of velvet antler tended to be greatest in HH (43<TEX>$\pm$</TEX>16g/day in 1998 and 51<TEX>$\pm$</TEX>14g/day in 1999) and least in LH (38<TEX>$\pm$</TEX>15g/day in 1998 and 45<TEX>$\pm$</TEX>18g/day in 1999).

Seasonal and Circadian Changes in the Home Ranges of Reintroduced Persian Fallow Deer

The Persian fallow deer (Dama mesopotamica)-among the rarest deer species in the world-has been gradually reintroduced, using individuals from a captive-bred population, in northern Israel since September 1996. As of October 2000, >80 animals were in the wild population. We studied seasonal and circadian attributes of deer home ranges to assess the success of the reintroduction in terms of behavioral adjustments to the wild. We used radiotelemetry to determine locations and analyzed home ranges with the adaptive kernel method. We defined 3 seasons: fawning (Mar-Jun), rut (Jul-Oct), and winter (Nov-Feb). For females (n = 16), rut home ranges were significantly larger than winter home ranges (449 ± 45 ha [mean ± SE] vs. 384 ± 36 ha, P 1,15 = 0.013). During fawning, female home ranges were intermediate (424 ± 51 ha). Males (n = 5) increased their home ranges in rut season (820 ± 162 ha [mean ± SE], P < 0.012) and shifted their locations toward the release point. In winter, males significantly decreased their home ranges (584 ± 158 ha, P < 0.012), shifted their locations away from the release point, and almost no overlap of core areas was noticeable (1.8% overlap). In fawning (the time of antler casting and regrowth), males continued to shift away from the release point and decreased home ranges (358 ± 66 ha, P= 0.049) with almost no overlapping of core areas (0.06% overlap). No statistically significant differences were found between day home ranges (males [n = 5]: 621 ± 220 ha [mean ± SD], females [n = 16]: 402 ± 164) and night home ranges (males: 482 ± 145, females: 389 ± 183), although day core areas tended to be larger (in all males and 12 of 16 females). All documented aspects of seasonally, in female and male home ranges are in accordance with the annual reproduction cycle, and are related to seasonal food availability. These results, combined with previous works, suggest that so far, the reintroduced Persian fallow deer have adjusted well to living in the wild and that the chances of achieving A self-wild population are good. However, further research for extended period should verify these conclusions.

Copper supplementation, velvet antler production and growth of rising 2-year-old red deer stags

AIMS: To investigate whether copper supplementation to rising 2-year-old red deer stags (Cervus elaphus) in winter and/or spring improved velvet antler weight, grade and financial value, and liveweight gain. METHODS: Rising 2-year-old red deer stags (n=142) on a commercial deer farm in Hawke's Bay were allocated to two groups on May 14, 1996. One group received 20 g boluses of copper-oxide wire particles. On August 15 each group was reallocated in a crossover design, each sub-group receiving either the same copper-oxide treatment or no treatment, to produce control, winter-only, winter-plus-spring, and spring-only copper treatment groups. Blood samples were collected for serum ferroxidase measurements from seven deer per group and all deer were weighed at 4–6-week intervals. Dates of antler casting and velvet removal, and velvet antler weight and grade were recorded, and the financial value of velvet calculated. Livers from a sample of deer slaughtered at the end of the trial mid-December were analysed to determine copper content. RESULTS: Supplementation with copper did not significantly alter velvet antler weight, daily velvet antler growth rate, days from casting to removal, grade or value, or stag liveweight gain. Serum ferroxidase concentrations averaged 10.0–23.7 IU/1 in control deer. Copper supplementation increased mean serum ferroxidase concentrations by approximately 10 IU/1. Mean liver copper concentration in control deer was 99 µmol/kg and ranged from 194 to 386 µmol/kg in the three treated groups. CONCLUSION: Group mean serum ferroxidase concentrations of 10 IU/1 and above are adequate for optimum velvet production and liveweight gain in rising 2-year-old stags.

Accessory antlers in male Cervidae

Accessory (supernumerary) antlers are an infrequent phenomenon in male cervids. These bony protuberances grow mostly from permanent pedicles, which developed in response to a repeated or a severe trauma to frontal, nasal or parietal bones. They regularly undergo seasonal mineralization, casting and regrowth and may persist for many years. Three examples of accessory antlers in telemetacarpal cervids, roe deer (Capreolus capreolus), white-tailed deer (Odocoileus virginianus) and moose (Alces alces), are presented. The initiation of accessory antlerogenesis, the progress of growth and development, and the mineralization and casting of accessory antlers were mostly identical or similar to processes observed in the antlerogenesis of lateral antlers. The antlerogenic property of the competent periosteum, located within the “antler territory”, appears to play a crucial role in the development of accessory antlers. The variability in location and the progress of development of accessory antlers, which were observed in several antlerogenic cycles, is discussed in relationship to the origin of deciduous antlers in extinct ancestors of cervids.

Effect of antiandrogen cyproterone acetate on the development of the antler cycle in Southern pudu (Pudu puda)

The antler cycle of pudu is similar to other cervids, but unlike most boreal deer, male Southern pudu (Pudu puda) exhibits two seasonal peaks of LH and testosterone. In that respect, pudu is similar to roe deer. Whereas the antler cycle in some deer species, such as roe deer or white-tailed deer, is very sensitive to variation of testosterone, in other cervids, such as fallow deer or reindeer, a blockade of androgens with cyproterone acetate (CA) has little or no effect on the timing of the antler casting. In order to test the sensitivity of pudu antlers to variations of androgens, CA (administered 2x weekly at 50 mg/buck) was injected intramuscularly for 3 weeks in 5 adult male pudu, starting February 19 (late summer). Four other males of similar age served as controls. The experiment was performed at the University of Concepcion, Chile, latitude 36.6 degreeS. Blood samples were taken once a week between January 19 and April 3. In CA-treated bucks, the antlers were cast approximately 3 weeks after the initiation of CA treatment and a new antler growth began almost immediately. The antlers reached about 5 cm in length, before ceasing to grow at the end of April, when they became mineralized and were subsequently polished. CA had no effect on the already declining levels of LH. Plasma levels of testosterone in controls increased from February 15, whereas in CA-treated bucks remained depresses until March 21. It is concluded that similarly to white-tailed deer, the antler cycle of Southern pudu is very sensitive to manipulation of androgen levels.

Brief communication. QTL for pubertal and seasonality traits in male Pere David's x red deer interspecies hybrids

The unique Pere David's (Elaphurus davidianus) x red deer (Cervus elaphus) backcross hybrid has been used to search for evidence of quantitative trait loci (QTL) for antler pubertal (date and live weight at pedicle initiation) and antler seasonality (date of antler cleaning and casting) traits in temperate species of deer. Analyses using marker information revealed evidence for a QTL for date at pedicle initiation (LOD = 3.7) and live weight at pedicle initiation (LOD = 3.1). These QTL explained 13% and 11% of the phenotypic variance in these traits, respectively.

Hard fallow deer antler: a living bone till antler casting?

Deer antlers are the only mammalian bone structures which regenerate completely every year. Once developed, antlers are cleaned of the velvet-like skin. Presently it is believed that due to velvet shedding the blood supply is interrupted in the solidifying antler bone. Histological examinations were made on different parts of fallow deer antlers investigated from the time of velvet shedding till the antler casting. The present study on hard (polished) antlers revealed living bone with regions presenting living osteocytes, active osteoblasts, osteoid seams and even early stages of trabecular microcallus formation, thus indicating to a continuous bone remodeling. A well developed vascular system was found despite the presence of hard antler bone. The pedicle bone exhibits a rich supply of capillaries and vessels connected to the spongy core of the main branch and the compact bone as well. There is evidence that hard fallow deer antlers possess a functioning vascular system that "keeps the antler moist" resulting in a high impact resistance when fights are most frequent. As late as 3 weeks prior to antler casting a large number of living cells were discovered within the antler core. As we have no doubt that parts of the polished fallow deer antler represent a living bone, we have concluded that a sufficient blood supply of the antler core is maintained almost till the time of antler casting by vessels passing through the antler base.

Seasonal Levels of Reproductive Hormones and Their Relationship to the Antler Cycle of Male and Female Reindeer (Rangifer tarandus)

Seasonal levels of LH, FSH, testosterone (T), estradiol, progesterone (P), and prolactin (PRL) were determined in the plasma of five adult bulls, and five barren and four pregnant cows of Alaskan reindeer (Rangifer tarandus), which were sampled every 3 weeks for 54 weeks. The male reproductive axis was sequentially activated; LH peaked in May–June (2 ng/ml), FSH in June (51 ng/ml), and T in September (11.8 ng/ml). LH levels in females reached a maximum in both groups at the end of August (the beginning of the rut). Seasonal variation in FSH was minimal in pregnant cows, but exhibited one elevation (41 ng/ml) in barren ones in November. T levels in cows remained at barely detectable levels. The decrease of T values observed in both groups in December and March was not significant. PRL peaked in May in cows (135 ng/ml pregnant, 140 ng/ml non-pregnant) and in June in bulls (92 ng/ml). Estradiol was highest in bulls in the rut (August), in non-pregnant cows in January and in pregnant cows in April, shortly before parturition. P levels in the pregnant cows rose from September and peaked (9 ng/ml) shortly before parturition in April. In the non-pregnant females P values increased and decreased several times before peaking (5 ng/ml) in March. In the males, the variation of T and estradiol levels correlated relatively well with the antler cycle but in the females the variation of neither estradiol, progesterone nor T appeared to be related to mineralization or casting of antlers.

Territory Establishment and Antler Cycle in Male Roe Deer

AbstractTerritory establishment and antler cycle in male roe deer, Capreolus capreolus, were studied in two areas in south‐eastern Sweden during 1989–1993. Initial territorial behaviour was observed in early Mar., when overlap between male ranges decreased from 66 % to 0 % over a 3–6‐wk period, as determined from telemetry data. The decrease was associated with an increased number of agonistic interactions. Most territories were established at the end of Mar. to early Apr., with a tendency for males re‐establishing old territories to be first. In all years, territories were taken up 1–3 wk before males shed velvet from their antlers. The distance between geometric centres of neighbouring males in winter and after territory establishment increased from 164 to 364 m. Former territory holders moved the geometric centres of their winter range and subsequent territory a shorter distance than first‐year territorials, 129 and 267 m respectively. Territory defence ceased after the rut in late Aug., and the spatial relations between neighbours reverted to the situation before the territorial season. Neither velvet shedding nor antler casting was correlated with male age (yearlings excluded), which contradicts earlier statements. Neither were there any associations between timing of antler casting and subsequent velvet shedding, nor vice versa. Hence, a male casting antlers early one year derives no advantage by early shedding the next season. Furthermore, to be in hard antlers is not a prerequisite for territory take‐up, whereas antlers probably are necessary for maintaining the area throughout the season. Functional aspects on roe buck territoriality are also discussed.

Effects of castration on antler growth in fallow deer (Dama dama L.).

Morphology and histological structure of antlers grown after castration (performed on March 25) were studied in six young fallow bucks. In the year after castration, antlerogenesis occurred during the species-specific time span, and the shape of the antlers, which remained permanently in velvet, was normal. During a cold period in December/January, the distal parts of the antlers suffered from frostbite and were subsequently detached. The process of sequestration was similar to that leading to normal antler casting. The sequestration sites were soon covered with skin, but (limited) regrowth of antler tissue from the stumps was not observed before late April/early May, i.e., the time of normal antler regeneration. Simultaneously, growth of knobby protuberances started on the surface of the antlers. Histological analysis of biopsies taken on December 20 in the year after castration revealed that the central parts of the antlers consisted of cancellous lamellar bone with mainly secondary osteons. Peripheral to this, the bone tissue (forming the protuberances) was of a more immature nature and exhibited larger intertrabecular spaces. The outermost layer consisted of woven bone formed by intramembranous ossification from the periosteum and was undergoing active growth and remodeling at the time of biopsy. Thus, bone formation at these sites occurred during a period when no antler growth is observed in normal fallow bucks. The velvet covering the bony protuberances was of normal appearance.

The influence of the stag on pubertal development in the red deer hind

AbstractThe possible influence of social factors on the timing of puberty in the hind was investigated utilizing seasonally advanced (melatonin-treated) hinds and stags. Melatonin treatment of both sexes resulted in a significant advancement in the onset of pubertal ovarian activity (26 days, P &lt; 0·001) and calving (27 days, P &lt; 0·001) in the treated hinds and antler casting (25 days, P &lt; 0·001) in the treated stags. Ovarian activity and calving were not influenced by melatonin treatment of the stags alone and similarly, antler casting was not affected by melatonin treatment of the hinds alone. However, a group of hinds without stags until after the onset of the breeding season, reached puberty later (5 days, P &lt; 0·05) than hinds with stags, suggesting the presence of the male is important in determining the timing of puberty.

The macroscopic and microscopic structure of double-head antlers and pedicle bone of Cervidae (Mammalia, Artiodactyla)

Ortho- and heterotopically formed double-head antlers were studied in red, fallow and roe deer. The malformation was the result of new antler growth without previous casting of the old antlers. Thus, two antler structures belonging to successive antler generations originated from one pedicle. These two structures were always separated by a horizontal groove. Histologically, signs of osteoclastic resorption were observed in the interior and at the outer circumference of the distal parts of the pedicles of the double heads. The resorptive process had, however, not been of an intensity necessary for subsequent antler casting. We also observed that the double-head's second antler generation had developed as a periosteal exostosis of the distal pedicle bone. Thus, we assume that in normogenesis formation of the bony component of subsequent antlers is also probably dependent on cells derived from pedicle periosteum. Finally, the process of antler regrowth in deer is compared with epimorphic regeneration occurring in other vertebrates.

Role of gonadal hormones in the regulation of the seasonal antler cycle in female reindeer, Rangifer tarandus.

The hormonal control of the seasonal antler cycle was investigated over 4 years in four adult female Norwegian reindeer, Rangifer tarandus, maintained in captivity at Tromsø, Norway (69 degrees N). The antlers were fully redeveloped in August, cleaned of velvet in September, and were retained in hard antler throughout the winter before being cast in March or April. The cleaning of the antlers occurred at the seasonal onset of ovarian activity and was associated with an increase in the blood plasma concentrations of testosterone, androstenedione, oestradiol and progesterone. Ovariectomy in October resulted in premature casting of the hard antlers in that year. This was paralleled with a decrease in the plasma concentrations of oestradiol and progesterone, but not of testosterone and androstenedione. Antlers were redeveloped, cleaned of velvet and cast each year in the ovariectomized females, but the antler cycle was abnormal since the cleaning of the antlers began 1-3 months later than in intact females and was often incomplete, and the casting surface of the old antler was deformed. The hardening of the antlers in the ovariectomized animals in autumn was correlated with seasonal increases in the plasma concentrations of androstenedione, but not in the concentrations of other steroid hormones; provocation tests using GnRH and arginine vasopressin (AVP) illustrated that the adrenal gland was a likely source of androgens. The initiation of antler growth in spring always followed the seasonal increase in the secretion of prolactin. The overall conclusion is that a gonadal steroid hormone, possibly oestradiol, normally acts to induce and maintain the hard antler state in female reindeer. This hormonal mechanism acts to synchronize the antler cycle to the seasonal reproductive cycle with the hard antlers functioning as weapons in intrasexual competition in winter.

General biology of sambar deer (Cervus unicolot) in captivity

Abstract Several biological measurements were made on captive sambar deer over 3 years (1989–92). Calving occurred from January to November, with a peak in April/May. Mean calving date was 8 May (SD = 71.3 days; n = 31). Calf mortality at birth was 28% (12/43), with the major causes being adult aggression and inclement weather. Mortality was higher in stag calves (41%) than hind calves (6%). Most adult stags were in velvet antler between January and April (mean = 125 days; SD = 22.6 days), and in hard antler between May and November (mean = 231 days; SD = 40.0 days), during which time rutting behaviour was observed. Mean dates of velvet stripping and hard antler casting were 17 April (SD = 14.9 days) and 7 December (SD = 35.4 days), respectively. These data are compared with similar data for farmed red deer. Sambar deer were found to be highly nervous and temperamental, but became more settled with regular human contact and feeding with maize and hay.

Effects of an antiandrogen treatment on the antler cycle of male fallow deer (Dama dama L.).

Weekly application of the antiandrogen cyproteron acetate (CA) to 3 adult (group 1, treatment starting 3 weeks prior to the rut) and 4 subadult (group 2, treatment starting after the rut) fallow bucks led to premature antler casting after about 9 weeks (group 1) or 16 to 17 days (group 2). Variation in time span between onset of CA administration and induced casting (in late November/early December) is attributed to age- and season-dependent differences in androgen levels before and during the treatment period. Casting surfaces of the antlers were flat. In all bucks, casting was followed by a complete though shortened antler cycle, occurring under short day conditions. In February/March velvet was shed from the antlers, indicating a rise in plasma androgen levels at that time. At time of fraying, antlers exhibited signs of immaturity and were shorter than normal. In the most pronounced case of immaturity, the antlers consisted mainly of cancellous woven bone, revealing that bone remodeling and antler mineralization had not occurred to a larger extent. These observations prove that onset of fraying behaviour does not depend on prior maturation of antler bone or necrosis of velvet. Occurrence of the additional antler cycle in late autumn and winter had no negative effect on subsequent antler formation starting in the following spring.

The mechanism of antler casting in the fallow deer.

The process by which antlers are detached from their pedicles was examined histologically in fallow deer castrated in the autumn to induce precocious casting. Osteoclastic erosion across an abscission line between the dead bone of the antler and the living bone of the pedicle was found to be responsible for the separation of the 2. As early as 3 days after castration, osteoclasts and associated lacunae were present on the sides of the pedicle bone. These were then found in progressively deeper locations, by 2 weeks extending across the entire width of the pedicle. Concomitant with the centripetal spread of osteoclasts was the enlargement of Haversian canals, the surfaces of which became lined with osteoclasts. These widening vascular channels within the bone were filled with connective tissue, which in precasting stages formed a mesodermal pad about 1 mm thick. In later stages, a circumferential cleft was excavated beneath the antler burr, and connective tissues from the surrounding pedicle skin invaded the space between the antler and pedicle. After casting, the ingrowing integumental tissues fused with the mesodermal tissues derived from the vascular channels of the pedicle to give rise to an incipient antler bud beneath the scab. The ingrowth of epidermis capable of de novo hair follicle formation gave rise to the future velvet skin that envelops the elongating antler.