Age-specific feeding cessation in male red deer during rut

Tactics for resource-use involve both using stored reserves (capital breeding) and feeding while reproducing (income breeding). In polygynous ungulates, males often use an income breeding strategy when young and shift to a capital breeding tactic at prime age. Little is known regarding why prime-aged males stop or largely reduce eating during rut but still remain inactive for as much time as before rut. A detailed exploration of how rumen content correlates with age and date may shed light on the ultimate causes of why some males stop eating. We provide quantitative empirical data on rumen content from red deer Cervus elaphus during the rutting season in Norway. In male red deer, rumen content declined with age, up to around 6 years of age. Above this age, rumen content was low and stable. A time-of-year effect on rumen content was best described with a second-order polynomial term, as rumen fill was lowest during mid-October when the mass loss of males and the ovulation rate of females both peak. We present two new hypotheses related to why males reduce eating ( physical rest and parasite hypotheses). Two related patterns need to be explained and better documented: (1) why are resting times stable before, after and during rut, and (2) why do non-prime-aged males eat more between rutting activities?     

Descriptive epidemiology of roe deer mortality in Sweden

A retrospective epidemiologic study was conducted to examine causes of mortality of 985 wild roe deer (Capreolus capreolus) submitted to the National Veterinary Institute (SVA; Uppsala, Sweden) from January 1986 to December 1995. Age, sex, body condition, and geographic distribution as related to disease conditions are reported herein. The most common causes of mortality in roe deer were trauma (19%), winter starvation (18%), gastritis/enteritis (15%), bacterial infections (11%), parasitic infection (11%), systemic diseases (11%), neoplasia (2%), congenital disorders (1%), and miscellaneous causes (6%). Cause of death was not determined in 6% of the cases. The distribution of causes of death reported in this study differ from previous works in Sweden in that infectious and parasitic diseases were more common than winter starvation. The pathologic findings in studies like this do not necessarily represent what is occurring in the natural environment, but they do provide a good indication of distribution of diseases over time as well as age and sex structure in relation to disease conditions. Further research and more detailed studies are in progress to better understand specific mortality factors as well as etiologies of certain described diseases in roe deer in Sweden.     

Hypodermosis of red deer in Spain

From February 1998 to January 1999, 106 red deer in the Autonomic Organism National Park "Quintos de Mora" (Toledo, central Spain) were evaluated to determine the prevalence and dynamics of infection with Hypoderma sp. by detection of subcutaneous larvae. Between six and 13 deer shot in selective hunting were examined monthly. Hypoderma sp. larvae were detected throughout the period except in June, July and August of 1998. Excluding the period during which no subcutaneous larvae were detected, the number of animals sampled was 80 (52 males and 28 females), belonging to three age classes: 12 calves (<1-yr-old), 19 yearlings (1-yr-old), and 49 adults (2- to 10-yr-old). All the third instar (L3) collected were identified as H. actaeon. Total prevalence during the period of larval detection was 61%. Prevalence in yearling and adult deer shot during the official hunting season was 89%. Monthly prevalence increased from September to January and decreased from February to May. In September and October, a small percentage of larvae were classified as first instar (L1). The rest of larvae collected between September and December were second instar (L2). Third instar (L3) predominated in January and February and was the only stage collected from March to May. Intensity ranged from 1 to 145 larvae. Intensities were >100 larvae in 6% of animals. Possible relationships of intensity or prevalence of infection with sex or age of the animals were evaluated. Significant differences in prevalence were observed among different host age classes. Prevalence was higher in yearlings (84%) than in adults (63%) and lowest in calves (17%).     

Elaeophorosis in red deer from Spain

Elaeophorosis, caused by Elaeophora elaphi, was observed in red deer (Cervus elaphus) from Toledo Province (Spain) for the first time. Adult specimens of Elaeophora elaphi were found in the hepatic vessels of nine of 151 red deer between October 1994 and September 1995; intensity of infection was two to 18 nematodes per host. Adult nematodes were only found during the period from fall through early spring. No differences were present between sex or age groups. Parasites were not found in a limited sample from fallow deer (Dama dama). Blood samples were negative for the presence of microfilariae.     

Influence of level of nutrition during late pregnancy on reproductive productivity of red deer I. Adult and primiparous hinds gestating red deer calves

The present study aimed to relate feed intake of red deer hinds during late pregnancy to dam body condition, foetal development and calf growth. Across 3 years, multiparous (n=33) or primiparous (n=18) hinds with known conception dates were housed in individual pens from days 150-220 of pregnancy, during which time they were each offered one of three daily allowances of pelletised rations (11 MJME/kg DM; 16% CP): high (H; ad libitum), medium (M; approximately 30% less; multiparous hinds only) and low (L; approximately 50% less). Restricted intake levels were retrospectively calculated from the mean intake of H hinds in the previous week. Hinds were returned to pasture at day 220 and calving was closely monitored. Liveweights, body condition score (BCS), and lactation score (LS) of hinds were recorded weekly from day 130 of pregnancy until calves were weaned at 12 weeks of age. Calves were tagged and weighed at birth, and subsequently weighed at 7 and 12 weeks of age. Additionally, hinds in the first year of study underwent CT scans on days 150 and 215 of pregnancy to assess compositional changes of the dam and conceptus. Mean daily ad libitum intakes of H hinds increased from 1.8 to 2.0 kg DM (0.6-0.7 MJME/kg0.75) at around day 150 to 2.8-3.2 kg DM (0.8-0.9 MJME/kg0.75) by day 220. Those of M and L hinds peaked at 1.8 and 1.6 kg DM, respectively, by day 220. This was reflected in significant treatment effects on liveweight gain and change in BCS and LS by the time of calving. CT scans indicated a significant treatment effect by day 215 on the mass of hind tissues (fat and lean) and a non-significant trend on conceptus/foetal weights. Despite apparent differences in foetal growth trajectories, there were no discernable treatment effects on sex-adjusted birth weights. However, there was an unexpectedly wide spread in calving dates that reflected considerable variation in gestation length. Furthermore, gestation length was negatively correlated with change in hind liveweight (but not BCS) between days 150 and 220 of pregnancy for all groups of hinds (P<0.05). Of three neonatal calf mortalities, none were related to overweight (dystocia) or underweight (non-viability) calves. Subsequent growth rates (g/day) of surviving calves did not reflect prior treatment of their dams, although variation in birth date influenced weights on specific dates. It is concluded from this study that while variation in nutrition to hinds during the last trimester may strongly influence foetal development, under conditions of modest feed imbalance, variation in gestation length compensates to ensure optimisation of birth weight.     

Proteome analysis of red deer antlers

Deer antlers are the only mammalian organs capable of repeated regeneration. Although antlers are known to develop from pedicles, which arise from antlerogenic cells of cranial periosteum, their developmental process is not fully elucidated. For example, while endocrine and environmental factors influence the antler development, it is still unclear which signaling pathways are involved in the transduction of such stimuli. To study the developmental process of antlers and identify proteins functioning in their growth, we have established proteome maps of red deer (Cervus elaphus) antlers. With two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization mass spectrometry, we analyzed more than 800 protein spots and identified approximately 130 individual proteins derived from the growing tip of antlers. The overall profile of the antler proteome was dissimilar to those of other types of tissue. Also comparison of proteomes derived from proximal bony tissue and the growing tip of antlers revealed substantial differences. Moreover several cell growth or signaling-related proteins are expressed exclusively in the growing tip, suggesting that these proteins function in the growth and differentiation of antlers. Currently, using the antler proteome maps, we are actively searching for the regulatory factor(s) that may control the antler development.     

Microsatellites reveal heterosis in red deer.

The fitness consequences of inbreeding and outbreeding are poorly understood in natural populations. We explore two microsatellite-based variables, individual heterozygosity (likely to correlate with recent inbreeding) and a new individual-specific internal distance measure, mean d2 (focusing on events deeper in the pedigree), in relation to two measures of fitness expressed early in life, birth weight and neonatal survival, in 670 red deer calves (Cervus elaphus) born on the Isle of Rum between 1982 and 1996. For comparison, we also analyse inbreeding coefficients derived from pedigrees in which paternity was inferred by molecular methods. Only 14 out of 231 calves (6.1%) had non-zero inbreeding coefficients, and neither inbreeding coefficient nor individual heterozygosity was consistently related to birth weight or neonatal survival. However, mean d2 was consistently related to both fitness measures. Low mean d2 was associated with low birth weight, especially following cold Aprils, in which foetal growth is reduced. Low mean d2 was also associated with low neonatal survival, but this effect was probably mediated by birth weight because fitting birth weight to the neonatal survival model displaced mean d2 as an explanatory variable. We conclude that in the deer population fitness measures expressed early in life do not show evidence of inbreeding depression, but they do show evidence of heterosis, possibly as a result of population mixing. We also demonstrate the practical problems of estimating inbreeding via pedigrees compared with a direct marker-based estimate of individual heterozygosity. We suggest that, together, individual heterozygosity and mean d2, estimated using microsatellites, are useful tools for exploring inbreeding and outbreeding in natural population.     

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.     

High red deer density depresses body mass of roe deer fawns

Many previous studies have pointed out that, when resources are limited, the potential for competition should be high among sympatric species that display overlaps in habitat and nutritional niches. However, reliable evidence of competition between red deer (Cervus elaphus) and roe deer (Capreolus capreolus) has not been yet reported for life history traits directly measuring performance such as body mass, reproduction, or survival. From long-term monitoring of deer populations in the reserve of La Petite Pierre (France), we measured the sex-specific responses of roe deer fawn body mass to changes in red deer density after accounting for possible confounding effects of date of shooting, climatic conditions, and roe deer density. As expected under the hypothesis of competition, red deer density in a given year had a marked negative influence on body mass of roe deer fawns born the same year and the following year. Fawn mass of roe deer males and females responded in similar ways to changes in red deer density. Our study provides the first evidence of a negative response of roe deer performance to high red deer density.     

Sex-specific strategies of dentine depletion in red deer

Worn teeth in herbivore ungulates may be related to lower efficiency in mastication and hence lower performance. However, selection should favour maximal performance in terms of body mass and reproductive capacity during reproductive lifespan, when permanent teeth are already partially worn. We hypothesize that wear rate may respond to a strategy of use of tooth materials (notably dentine), which balances instantaneous wear rate and performance against tooth preservation for future performance and reproduction. In the present study, we investigated 4151 carcasses of Iberian red deer Cervus elaphus hispanicus and show that more worn molars were not related to lower performance throughout age. By comparing between sexes, tooth wear rates were smaller in females than in males, but the relationship between tooth wear and body performance also differed between the sexes: females did not show a significant relationship between tooth wear and performance but males with more worn teeth were in general heavier and had larger antlers until senile age, when more depleted teeth were related to smaller antlers. These results reveal, for the first time, sex-specific lifetime strategies of dentine expenditure: maintenance of performance ability throughout a longer reproductive lifespan in females, compared with maximizing current performance by depleting dentine reserves within a shorter lifespan in males.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 487–497.     

Winter ecology of nonmigratory Alpine red deer

In winter, red deer (Cervus elaphus hippelaphus) that are not receiving supplementary feeding emphasize and rely on energy-saving strategies. In severe winters with deep snow, they select a home-range habitat-windblown alpine pastures above the timberline-that meets the requirements of this strategy: a much lower sinking depth and good forage availability are due to patchy snow distribution, while the open area provides higher radiation, permits group formation and thus sociobiological wellbeing. The energy costs of thermoregulation are minimized by selecting slopes with south to south-west exposures, seeking thermal shelter from strong winds, while high flight distances and horizontal flight routes reduce the energy costs of fleeing. In years with little winter snowfall non-supplemented red deer prefer the greater security of forested habitats in lower areas and obtain higher food intake from slightly more nutritious meadows in the valley bottom. The food-supplemented herd has much more constant and predictable habitat use, combining an energy-saving strategy-choosing alpine pastures as low-cost winter home range-with high energy income at the feeding station.     

Mitotic activity in the growing red deer antler

Antlers grow rapidly through the coordinated development of both osseocartilage and skin (velvet). The regional patterns of cell division in these two compartments were assessed by immunochemical detection of proliferating cell nuclear antigen (PCNA) in antlers from one-year-old red deer. The whole antler integument was in a state of growth and/or renewal, particularly the keratinocytes of the basal cell layer of the epidermis near the tip, and hair bulbs and sebaceous glands. More proximally, a zone of weaker mitotic activity was detected. Within the osseocartilagenous compartment, rapid mitosis was particularly apparent within the distal mesenchyme, visible as a dome-shaped band of staining. Mitotic activity of chondrocytes and osteoblasts was more extensive in peripheral areas of developing bone than in the centre. We conclude that the antler tip is the site of most active epidermal growth, and hypothesise that other mechanisms in addition to mechanical stretching play a role in growth of the integument.     

Incidence of ovulation before the onset of the rut and during pregnancy in red deer hinds

Abstract

Ovaries were recovered from red deer hinds culled in South West and in 1973–1976 during late pregnancy/early lactation (13 November – 18 December), the non-breeding season (10 January – 23 February), the period just before the onset of the rut (16 March – 11 April), and early pregnancy (13 May – 1 June). The percentage of hinds with a corpus luteum just before the onset of the rut was low (16.3% of adult hinds). An accessory corpus luteum of pregnancy was found in 46.8% of hinds in early pregnancy and in 58.9% in late pregnancy/early lactation (the difference is not significant). The accessory corpus luteum was about half the size of the primary corpus luteum of pregnancy. It appeared that the accessory corpus luteum was formed early in the breeding season, and persisted until parturition.     

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.