Influence of plane of winter nutrition on plasma concentrations of prolactin and testosterone and their association with voluntary food intake in red deer stags (Cervus elaphus)

Blood samples were taken at weekly or 3-weekly intervals from 12 red deer stags, from 3 weeks of age until 3 years of age. Six of the stags were fed to appetite throughout the study and six were maintained on 70% as much during each winter and to appetite each summer. All plasma samples were analysed for testosterone and prolactin. Food intake was measured daily. Annual rhythms of testosterone, prolactin and food intake were evident. Peaks of prolactin, on an increasing photoperiod tended to occur slightly before peaks of food intake and troughs of food intake on a decreasing photoperiod occurred at or slightly after peaks of testosterone. The reduced plane of winter nutrition tended to delay rather than alter the amplitude of the annual cycles of testosterone, prolactin or food intake. Several of the unrestricted stags showed biannual rhythms of testosterone, prolactin and food intake accompanied by additional cycles of coat development and antler growth. These additional cycles tended to be 6 months out of rhythm with normal cycles. It is considered that this is due to the stags being stimulated by a particular day-length irrespective of whether it is decreasing or increasing and that plane of nutrition may influence the control of phase blockers.     

Endocrine control of antler growth in red deer stags

Observations of body weight, testis size, antler status, plasma testosterone and prolactin were made on 12 red deer stags during their first 2 years of life. Six of the stags were fed to appetite throughout the study (Group A) and 6 were fed a 70% restricted diet during each winter (Group B). In addition 6 of the stags , 3 from each group, were studied in more detail; LH and testosterone were measured either after a single injection of LH-RH or in samples taken at frequent intervals over a period of 8 or 24 h. During the study the stags became sexually mature, developed first their pedicles and then antlers and showed at least one complete cycle of casting and regrowth of the antlers . The stags in Group A developed their testes and pedicles about 2 months earlier than did those in Group B. Pedicle initiation was associated with increasing plasma testosterone levels in response to changes in LH secretion, and antler development occurred when testosterone levels were low or decreasing. Cleaning of the velvet was associated with high levels of plasma testosterone. Antler casting occurred when plasma testosterone concentrations were low or undetectable and prolactin levels were high or increasing. The relationship between LH and testosterone varied during the study; in spring when the testes and antlers were growing, relatively high levels of LH were associated with only small peaks of testosterone, yet in summer, when antler growth was complete and the antlers were clean of velvet, low LH concentrations were associated with large peaks of testosterone.     

Some properties of Red deer (Cervus elaphus) at exceptionally high population-density in Scotland

This paper records some features of Red deer ( Cervus elaphus L.) at very high population density on a Scottish island. About half the total population was shot-out in autumn 1974, and half the remainder in autumn 1975, with special searches for deer which had died of natural causes during the intervening year. In all, the animals examined amounted to 80% of the original population, and from the data gathered it was possible to (i) assess the structure and reproductive features of the original population; (ii) examine the level of animal performance at this exceptionally high population-density; and (iii) check for any changes in performance arising from the initial reduction in density.
The sex-ratio of adults in the original population showed a small excess of hinds, stags being apparently subject to a higher mortality rate than hinds after about six years of age. In performance, these deer were much the same as those living elsewhere on Scottish hill-land at relatively high population-density, i.e. with delayed puberty and poor breeding rates in hinds, and with much smaller adults than in woodland habitats. But, contrary to expectation, the general level of performance was not unusually low for Red deer on Scottish hill-land, and there was no evidence of transmissible diseases or excessive parasitism. It was also surprising that the animals showed no improvements in performance following their first reduction; if anything, they were slightly poorer after one year at reduced density. This may have been a temporary consequence of the severe disruption of existing behaviour patterns brought about by the sudden loss of many groups of deer.     

Effects of melatonin implants on reproductive seasonality of male red deer (Cervus elaphus)

Red deer stags were treated with melatonin implants in 2 experiments designed to examine the control of reproductive seasonality. In Exp. 1, stags (n = 24) were allocated to 4 treatment groups: 2 groups were treated with 3 implants per stag each month from 8 November to 5 February (EM) or 9 December to 5 February (LM), 1 untreated group of control stags remained with the melatonin-treated stags (CC) and the other untreated control group remained isolated (IC). Melatonin treatment advanced the seasonal changes in scrotal circumference, liveweight, antler state and coat type compared with control stags. The extent of advancement was greater in EM than LM stags. In EM and LM stags, size of testes regressed rapidly and antlers were cast shortly after melatonin implants became exhausted in March. This was followed by an additional antler cycle and reproductive development and decline from June to November. EM and LM stags became synchronized with control stags 14-15 months after melatonin treatment began. The extra cycle of seasonal changes was more pronounced in EM than in LM stags. In Exp. 2, stags (n = 30) were allocated to 6 treatment groups: 4 groups were treated with 3 implants per stag at monthly intervals for 6 months from 22 June (J), 4 August (A), 16 September (S) and 23 October (O), a further group of stags was treated in the same manner for 12 months from 22 June (Y), and the remaining group was untreated (C). Compared with control stags, testicular regression and antler casting was delayed in Groups J, A and Y. These events occurred at the same time as in control stags in Groups S and O. Subsequent reproductive development was advanced in Groups S and O and delayed in Groups J, A and Y. The results demonstrated that treatment with melatonin implants in November or December advanced reproductive development. However, when stags were treated with melatonin implants from June to August, reproductive development was delayed, indicating a change in response to melatonin treatment during the year. The change in response to melatonin treatment between late winter and early spring was interpreted as a resetting of an endogenous circannual rhythm caused by a photoperiodic cue responsible for initiating the final stages of reproductive regression.     

Effects of environmental conditions, human activity, reproduction, antler cycle and grouping on fecal glucocorticoids of free-ranging Pampas deer stags (Ozotoceros bezoarticus bezoarticus)

In this study, a commercial enzyme immunoassay (EIA) was validated in detecting glucocorticoids in Pampas deer feces, in order to investigate the influence of several factors on the adrenocortical function. Fecal samples, behavioral data and information concerning male grouping and antlers status were collected at a monthly basis during a 1 year period from free-ranging stags living at Emas National Park, Brazil (18 degrees S/52 degrees W). The results revealed that concentrations of fecal glucocorticoids in winter were significantly higher than those corresponding to spring and summer. In addition, dry season data presented higher levels than during the wet season. Significant difference was found between fecal levels of breeding stags in summer and nonbreeding stags, whereas no difference was observed between breeding stags in winter and nonbreeding stags. On the other hand, males from areas with frequent human disturbance exhibited higher glucocorticoid concentrations and flight distances than individuals from areas of lower human activity. Males with antlers in velvet had elevated levels compared with animals in hard antler or antler casting. Also, we found that glucocorticoid levels were higher in groups with three or more males than in groups with only one male. The flight distances showed positive correlation with fecal glucocorticoid. These data indicate that fecal glucocorticoid provides a useful approach in the evaluation of physiological effects of environment, inter-individuals relationship and human-induced stressors on free-ranging Pampas deer stags.     

Seasonal migration of male red deer (<Emphasis Type="Italic">Cervus elaphus</Emphasis>) in southern Sweden and consequences for management

Red deer Cervus elaphus is a highly appreciated and intensively managed game species throughout Europe. A common management objective is a sustainable harvest of large trophies. In southern Sweden, management has mainly aimed at preserving the nominate subspecies C. elaphus elaphus. Seasonal migration of red deer males may, however, complicate both harvest management as well as conservation efforts. I used individually identified male red deer in southern Sweden to observe distance travelled from rutting areas to areas used by males in summer and winter. Adult males were identified by antler shape and photo-documented during rut. Photos from the rut were compared to trophies of deer harvested or found dead, to found cast antlers and to stags photographed during summer. From 1969 to 2007, a distance between rutting ground and summer/winter quarters was established for 96 identified stags. An average distance of 14 km and a maximum distance of 47 km were recorded between rut and summer/winter observations. The seasonal migration of males increases the risk of overexploitation of males with harvest in both rutting areas and wintering areas. Harvest management and conservation efforts may fail if males seasonally migrate outside the management unit. The results suggest that seasonal migration must be considered in harvest management and conservation and that there is a need for a regulation of male harvest. Furthermore, the study stresses that the success in deer management of single hunting units, may be largely dependent on the harvest policies in the near surroundings as well as in areas tenths of kilometres away, suggesting that a successful management must rely on co-operation and co-ordination on a landscape scale.     

甲状腺功能对调节雄性马鹿体重和繁殖活动季节性变化的研究

本研究探讨了甲状腺功能对雄性马鹿体重和繁殖活动季节性变化的调节作用,试验１从１９８８年１月（夏季）开始到１９８９年６月（冬季）结束,对照组５头正常鹿体中,血浆Ｔ３水平具有明显的季节性变化（Ｐ＜０．０１）,在秋季和冬季较低,春季至秋季早期较高,而３头甲状腺摘除（ＴＨＸ）鹿血浆Ｔ３水平在１９８８年６月后（冬季）降低到不可测水平。在１９８８年９月以前,二组鹿的体重,睾丸直径和血浆睾酮水平的季节性变化趋势     

Social dominance in farmed red deer stags

The dominance hierarchy was observed and recorded in a group of five farmed rising 5-year-old red deer stags, kept apart from hinds, from February 1982 until September 1982. The stags were observed at approximately fortnightly intervals during this period. The frequency of roaring and of serious fighting was also recorded. The identity of the dominant stag altered during the study on five occasions; a triangular dominance relationship was observed in only one observation period, and otherwise the hierarchy was linear. The roaring rate was high during the period when sexual activity would have taken place if hinds had been available, and the frequency of serious fighting was highest when one particular stag was dominant. Dominant stags showed no tendency to selectively harass subordinates in particular hierarchial positions. Although body weight was not related to rank at the beginning or end of the study, it was after 8 weeks had elapsed. Deer farmers who must keep adult stags together during the winter should maximise spacing to reduce aggression, and if necessary cull out trouble-makers.     

Antler size and fluctuating asymmetry in red deer (Cervus elaphus) stags and probability of becoming a harem holder in rut

Red deer hinds play a significant role in selecting stags for mating. We tested the hypotheses that in red deer ( Cervus elaphus ) the probability of becoming a harem holder (and hence achieving reproductive success) occurs in stags bearing larger, branched antlers and showing low fluctuating asymmetry (FA). Eleven antler characteristics were measured; absolute and relative FA were calculated on 51 cast antler sets from 19 individually recognized stags. Probability of becoming a harem holder (PBHH) was originally analysed separately, i.e. for antler size and FA of each antler characteristic and calculated factors for both antler size and FA. If analysed separately, large antler size and low relative but high absolute FA increased PBHH. When we combined antler size and FA of antler characteristics in one model using antler size and FA factors, however, PBHH and achieving reproductive success were mainly dependent on increasing antler size and enhanced antler branching rather than on FA. We conclude that in contrast to antler size, FA is unlikely to play any significant role in sexual selection as an indicator of individual quality.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 87 , 59–68.     

雄性麋鹿的交配机会、社会等级和皮质醇水平

我们在北京麋鹿苑研究了发情期雄性麋鹿的社会行为、社会等级和血清皮质醇水平,并分析了三者间的相互关系。按照雄性麋鹿的行为,将雄性麋鹿分为优势群和从属群。优势群包括群主和挑战者,从属群包括单身汉和被淘汰群主。使用SJ—Ⅰ型事件记录器进行常规行为取样,用放射免疫分析法测定血清皮质醇含量。发现：(1)优势雄鹿的发情行为频次明显高于从属雄鹿;(2)攻击行为的发生频次在两组间无显著差异;(3)血清皮质醇含量在两组间也无显著差异。由此我们认为,发情期雄性麋鹿的社会等级序位影响许多行为的表达,优势雄鹿成功交配的机会比从属雄鹿多。而攻击行为和肾上腺皮质醇的分泌与社群等级无明显相关,可能是麋鹿在圈养状态下的一种适应策略,这将有利于缓解发情期雄鹿的紧张,从而允许更多的能量投放在发情交配上。     

Long-term stimulatory effects of a continuous infusion of LHRH agonist on testicular function in male red deer (Cervus elaphus)

Red deer stags were infused continuously with the LHRH agonist buserelin at 180-270 micrograms/day (1.2-1.8 micrograms/kg/day) for 72 days starting in late winter with the aim of suppressing reproductive function and inducing premature casting of the antlers. Contrary to expectation, the treatment resulted in a long-term stimulation of testicular activity lasting at least 2 months; the increases in plasma concentrations of testosterone were associated with an increase in aggressive behaviour and the development of rutting odour in the urine. The stags cast their antlers at the normal time in spring after the end of the treatments. The results indicate that the pituitary gonadotroph cells in the stag can continue to secrete LH in response to chronic exposure to an LHRH agonist and do not become rapidly desensitized. The effect of the agonist is therefore to cause significant stimulation of testicular activity which is a conspicuous response in the non-breeding season when the stags are already in a hypogonadal state.     

Experiences in deer sperm cryopreservation under practical conditions--a pilot study

The genetic potential of the red and fallow deer populations in Hungary is well known. Conserving the variability in this excellent genetic material for game preservation is one of our most important task. The aim of the present pilot study was to test the logistical steps of a sperm processing and storing system in which deer sperm can be stored at a level that meets quality standards accepted for domestic animals. Moreover, two different semen extenders, commercially used for freezing bull semen, were compared from the viewpoint of applicability to freeze fallow deer sperm. Sperm was collected from epididymes of eight red stags (Cervus elaphus hippelaphus) and six fallow bucks (Dama dama) during the rutting season. Red deer samples were washed in Triladyl extender, while fallow deer samples were split and processed in Triladyl or Bioxcell extender. In the samples, which had a shorter time interval between the death of the animal and the sperm collection, the percentage of viable spermatozoa with intact acrosome was typically higher.     

Feeding Tactics of Low-ranking Red Deer Stags at Supplementary Feeding Sites

We tested the hypothesis that low-ranking red deer Cervus elaphus stags adjust feeding tactics according to the spatio-temporal availability of the food. We observed free-ranging red deer at two supplementary feeding sites in the Scottish Highlands. It was predicted that at spatially clumped food, low-ranking stags would avoid high-ranking stags, 1. spatially when food is available only for a short period, but 2. temporally when the food is available continuously.
We observed several feeding tactics in low-ranking stags and the prevalence of a feeding tactic was related to the spatial distribution of the food. When food was highly clumped some low-ranking stags rushed in between feeding high-ranking stags, took a bite and retreated to process the bite (sneaking tactic). Bite rate/min did not differ between sneaking (0.29 ± 0.05) and non-sneaking low-ranking stags (0.26 ± 0.05). Compared with non-sneaking low-ranking herd members, sneaking stags took larger bites, as reflected in a significantly longer handling time (125 ± 12.4 s/bite) and thus achieved a higher intake, although still considerably less than high-ranking stags.
The temporal availability of the food did not influence feeding tactics in low-ranking stags. Low-ranking stags always avoided higher-ranking herd members spatially but did not shift their feeding bouts to times of the day when high-ranking stags were not feeding.     

Mandibular osteomyelitis in red deer (Cervus elaphus hispanicus) and fallow deer (Dama dama): occurrence and associated factors in free-living populations in southern Spain

The prevalence of mandibular osteomyelitis, which results in a condition called lumpy jaw, and factors associated with its occurrence were investigated in syntopic free-living populations of red deer (Cervus elaphus hispanicus) and fallow deer (Dama dama) in Spain. The study material consisted of 3,586 mandibles from 2,548 red deer and 1,038 fallow deer shot during sport hunting, herd management culls, and programs for population control between 1988 and 1997 (period 1) and 2002 and 2009 (period 2) in eastern Sierra Morena, southern Spain. Disease prevalence ranged from 0.36% to 10.91% among age groups. Older animals were significantly more likely to be affected than younger ones. Red deer stags had higher prevalence than other groups. There was a significantly higher prevalence in period 1, probably associated with differences in climatic and population conditions. High population densities of female red deer contributed significantly to occurrence of disease. Intensive herd management and poor environmental conditions were considered risk factors that increased susceptibility to disease. The study of this affliction could be useful for monitoring general herd welfare and ecologic changes in Mediterranean ecosystems.     

Estimating red deer (<Emphasis Type="Italic">Cervus elaphus</Emphasis>) population size in the Southern Black Forest: the role of hunting in population control

Numerous studies have addressed the question of whether hunting is capable of limiting the abundance of ungulates in the northern hemisphere. We investigated whether the hunting of red deer (Cervus elaphus) has reduced their abundance in the Southern Black Forest (area 17,500 ha), Southern Germany, since 2006. Red deer abundance was estimated using data obtained from visual counts at winter feeding sites, track counts, and bag records. An age- and sex-structured population model to estimate the winter population size was also constructed using bag records. The estimated red deer population size was evaluated according to a non-invasive genetic mark-recapture approach. The results showed that the hunting of red deer can reduce their population size if the hunting regime is part of a holistic management concept that takes into account the uncertainty of population size estimates and is implemented at scales appropriate to the management of this species.     

Sexual segregation and density-related changes in habitat use in male and female Red deer (Cerrus elaphus)

Sex differences in diet and habitat use in Red deer occur in several areas of Scotland. In some cases, they are a consequence of differences in the altjtude levels used but, on Rhum, both sexes use the same levels, concentrating in different areas of the same plant communities. Segregation between the sexes is most pronounced for animals feeding on short grasslands and increases in winter and at high population density. These results support the hypothesis that stags are less tolerant of low plant biomasses than hinds and can be excluded from mutually preferred communities by indirect competition     

Low genetic variation support bottlenecks in Scandinavian red deer

Loss of genetic variation from genetic drift during population bottlenecks has been shown for many species. Red deer (Cervus elaphus) may have been exposed to bottlenecks due to founder events during postglacial colonisation in the early Holocene and during known population reductions in the eighteenth and nineteenth centuries. In this study, we assess loss of genetic variation in Scandinavian red deer due to potential bottlenecks by comparing microsatellite (n = 14) and mitochondrial DNA variation in the Norwegian and Swedish populations with the Scottish, Lithuanian and Hungarian populations. Bottlenecks are also assessed from the M ratio of populations, heterozygosity excess and from hierarchical Bayesian analyses of their demographic history. Strong genetic drift and differentiation was identified in both Scandinavian populations. Microsatellite variation was lower in both Scandinavian populations compared with the other European populations and mitochondrial DNA variation was especially low in the Swedish population where only one unique haplotype was observed. Loss of microsatellite alleles was demonstrated by low M ratios in all populations except the Hungarian. M ratios’ were especially low in the Scandinavian populations, indicating additional or more severe bottlenecks. Heterozygosity excess compared with the expectation from the number of observed microsatellite alleles suggested a recent bottleneck of low severity in the Norwegian population. Hierarchical Bayesian coalescent analyses consistently yielded estimates of a large ancestral and a small current population size in all investigated European populations and suggested the onset of population decline to be between 5,000 and 10,000 years ago, which coincide well with postglacial colonisation.     

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 degrees 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.     

Requirement of thyroid function for the expression of seasonal reproductive and related changes in red deer (Cervus elaphus) stags.

The effect of thyroid function on regulation of seasonal reproduction was investigated in three red deer stags thyroidectomized (THX) in summer (January 1988) in comparison with five thyroid-intact controls. Responses of luteinizing hormone (LH) and testosterone to a bolus injection of 10 micrograms gonadotrophin-releasing hormone (GnRH) were tested in July, October, December, February and April. Blood samples were collected at weekly intervals from December 1987 to June 1989 for measurement of testosterone, triiodothyronine (T3) and prolactin concentrations. Testis diameters were measured every 2 weeks. In October 1988 (spring), plasma LH concentrations of control stags were less responsive (P less than 0.01) to stimulation by GnRH than those of THX stags; plasma testosterone concentrations and testis diameters were low and there was no increase in plasma testosterone concentrations after injection of GnRH in control stags during October or December (spring, early-summer). In contrast, THX stags maintained a testosterone response (P less than 0.01) in these 2 months and did not exhibit any signs of a seasonal lack of reproductive activity at this time of year. Control stags cast antlers in spring whereas THX stags maintained hard antlers throughout the study. Concentrations of plasma T3 were not detected in THX stags from June 1988 onwards, but exhibited a seasonal pattern in control stags, with low concentrations during autumn and winter (April to July) and high concentrations in spring and summer (August to February). There was no effect of thyroidectomy on the seasonal pattern of prolactin secretion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of plane of nutrition on seasonality of reproduction in Spanish Payoya goats

The aim of this study was to determine if there is a seasonal pattern of sexual activity in female Payoya goats and if this seasonality could be modulated by nutrition. During the experimental period of 20 months, 43 non-pregnant adults goats were penned under natural photoperiod at latitude 37 degrees 15'N. At the onset of the experiment, the animals were allocated to three experimental groups differing in the level of nutrition and whether the animals were entire or ovariectomized does. The high nutrition group (H, n = 16 entire does) receiving 1.5 times maintenance requirements. The low nutrition group (L, n = 16 entire does) and an ovariectomized and oestradiol treated group (OVX, n = 11 ovariectomized does) received a diet supporting their maintenance requirements. The groups were balanced for live weight (LW) and body condition score (BCS) at the beginning of the study. In entire goats, oestrus was tested daily using aproned males, ovulation rate was assessed by laparoscopy 7 days after identification of oestrus and plasma samples were obtained twice per week for progesterone assay. OVX goats were isolated from the other groups and bucks, plasma samples were assayed twice per week for LH and there were four intensive sampling periods during the year to determine LH pulsatility. LW and BCS were recorded for all animals once a week. A clear circannual cycle in live weight change was observed in all experimental groups, being relatively stable or slightly decreasing in summer and autumn and increasing during winter and spring. The effect of exposure to high (H) rather than low (L) nutrition was to cause earlier onset of ovarian activity (5 versus 17 August; P < 0.05), and expression of oestrous (16 August versus 2 September; P < 0.01) and later cessation of reproductive activity (ovulation 11 February versus 17 January; P < 0.01). Consequently, seasonal anoestrus was 32 days shorter in does on the higher plane of nutrition (P < 0.01). The seasonality of reproductive activity was confirmed in the OVX does, with reduced LH concentrations during spring and summer, and increased LH concentrations in autumn and winter. There was no effect of nutrition on ovulation rate. These results demonstrate that the female Payoya goat exhibits marked reproductive seasonality which is modulated by nutrition but possibly not ovulation rate.