Environmental constraints on reproductive performance of farmed deer

Impacts of nutrition on reproduction in female red deer: phenotypic flexibility within a photoperiod-mediated seasonal cycle

Red deer (Cervus elaphus) are widely distributed throughout cold northern temperate latitudes, where they have evolved to cope within highly seasonal continental environments. Naturalisation of red deer to the more moderate seasonal (but variable climatic) environment of New Zealand has been spectacularly successful, and they are widely farmed in the country’s pastoral environment for venison and antlers. The species is genetically programmed to exhibit photoperiodic control of voluntary feed intake, growth and reproduction, ensuring that energy demands are aligned with seasonally available resources and offspring are born in summer when climate is favourable for survival. However, despite genetic control of their endogenous seasonal cycles, there appears to be a strong ability for environmental factors such as nutrition to generate large phenotypic variation of seasonal traits. This may have contributed to their successful naturalisation to a wider range of seasonal environments than would be expected within their ancestral range. While precise timing of conception and duration of gestation length are the two fundamental mechanisms by which the strict seasonality of birth is maintained in seasonally breeding mammals, red deer exhibit considerable variation in both these traits. The present paper examines the outcomes of recent studies on farmed red deer on the impacts of lactation on conception date, the influence of nutrition during pregnancy on gestation length, and early life growth effects on the onset of female puberty. These studies have collectively demonstrated that while red deer are assumed to be under fairly rigorous genetic control of seasonality traits, they have a repertoire of phenotypic variation at various points of the reproductive cycle that may potentially allow a degree of adaptation to climatic variation that influences annual feed supply. This may explain the success of red deer in colonising a range of new environments that differ seasonally from their ancestral environment.

Seasonal variations in serum concentrations of testosterone, testicular volume and neck circumference of fallow deer (Dama dama) kept ex situ in a tropical region

The fallow deer (Dama dama) is a species of Cervidae commonly kept in captivity, either in commercial farms or in zoos. The reproductive seasonality of this species is well known in the northern hemisphere, where photoperiod is a decisive factor in androgenic activity and, consequently, in the development of secondary sexual characteristics among male adults. The maintenance of this species in tropical regions has been successful, but there are no studies that demonstrate the maintenance of reproductive seasonality under these climatic conditions, which was the objective of the present study. To do so, the present investigation involved 27 fallow deer (D. dama) specimens, of which 14 were adults and 13 prepubescent (<8 months) individuals, all assessed during and outside (December-February) the reproductive season (June-August). The serum concentrations of testosterone, testicular volume, and neck circumference were analyzed among all animals during both seasons. The reproductive season was marked by expressive hormonal concentrations, increasing neck circumference and testicular volume, differing significantly between adults and prepubescent individuals outside the season. Positive correlations were observed among all analyzed variables: mean testicular volume and neck circumference (r = 0.92, p < 0.0001), testicular volume and testosterone concentrations (r = 0.79, p < 0.0001) and between neck circumference and testosterone concentrations (r = 0.67, p < 0.0001). Given the results found, the conclusion is that even under tropical climate conditions the reproductive seasonality of the fallow deer is well defined and may be related to photoperiod.

Morphometric and hormonal changes following persistent handling in pregnant blue fox vixens (Alopex lagopus)

Modern, intensive fox breeding implies a human-animal relationship but human contact causes stress in farm-bred blue foxes. Handling is a common part of routine farming practices, particularly during the breeding season. The purpose of this study was to determine how handling influences certain morphometric and hormonal parameters of adrenocortical and ovarian function and fertility in pregnant blue foxes and whether these effects are mediated through an increase in plasma concentrations of cortisol. Blue fox females were subjected to a 1-min daily-handling treatment in the last trimester of pregnancy (term = 52 days). Plasma concentrations of ACTH, cortisol, progesterone, oestradiol and testosterone, as well as the in vitro adrenal and gonadal production of steroids were measured by radio-immuno assay in control (C, no. = 6) and handled (H, no. = 7) vixens on days 47 to 48 of pregnancy. In addition, the number of viable and dead foetuses, body, adrenal and ovarian weights in pregnant foxes and body weights of their viable foetuses were recorded. Handling increased plasma concentration of cortisol (C: 6·8 (s.e. 1·6) ng/ml v. H: 22·8 (s.e. 5·9) ng/ml, P < 0·05) as well as in vitro adrenal production of cortisol. In addition, handling decreased the body (C: 7·40 (s.e. 0·48) kg v. H: 6·24 (s.e. 0·13) kg, P < 0·05) and ovarian (C: 3·45 (s.e. 0·26) g v. H: 2·73 (s.e. 0·17) g, P < 0·05) weights of pregnant vixens and also the body weight of viable foetuses (C: 59·1 (s.e. 0·9) g, no. = 73 v. H: 50·6 (s.e. 1·2) g, no. = 58, P < 0·01). Handling did not cause any changes in adrenal weight, plasma concentrations of progesterone and oestradiol or in vitro ovarian steroid production. It is concluded that persistent handling of pregnant blue foxes is a mild stressor, which results in an increase in plasma concentration and adrenal production of cortisol and reduces maternal and foetal body weights.

Habituating to handling: factors affecting preorbital gland opening in red deer calves

The preorbital gland plays not only an olfactory role in cervids but also a visual one. Opening this gland is an easy way for the calf to communicate with the mother, indicating hunger/satiety, stress, pain, fear, or excitement. This information can be also useful for farm operators to assess how fast the calves habituate to handling routines and to detect those calves that do not habituate and may suffer chronic stress in the future. Thirty-one calves were subjected to 2 consecutive experiments to clarify if observing preorbital gland opening is related to habituation to handling in red deer calves (Cervus elaphus). Calves were born in 3 different paddocks, handled as newborns (Exp. 1), and then subjected to the same routine handling but with different periodicity: every 1, 2, or 3 wk (Exp. 2). In Exp. 1, preorbital gland opening was recorded in newborns during an initial handling (including weighing, ear tagging, and sex determination). Preorbital gland opening occurred in 93% of calves during this procedure and was not affected by sex, time since birth, or birth weight. Experiment 2 consisted of measuring preorbital opening during the same routine handling (weighing, blood sampling, and rump touching to assess body condition) when calves were 1, 3, and 5 mo old. Binary logistic regression showed that gland opening was associated with habituation to handling, since at 1 and 3 mo the probability of opening the gland decreased with the number of handlings that a calf experienced before (P = 0.008 and P = 0.028, respectively). However, there were no further changes in preorbital gland opening rate in the 5-mo-old calves (P = 0.182). The significant influence of the number of previous handlings on the probability of opening the preorbital gland was confirmed through generalized linear model with repeated measures (P = 0.007). Preorbital gland opening decreased along the phases of the study. Nevertheless, we found a significant trend in individuals to keep similar opening patterns (intraclass correlation coefficient = 0.807, P < 0.001), which suggests that the more stressed individuals can be detected with this method. Therefore, we conclude that preorbital gland opening during routine handlings is related to the number of previous handlings, and thus it can be used as an indicator of lack of habituation to handling in farmed cervids.

The relationship between body-mass and puberty in young red deer (Cervus elaphus) hinds: evidence of early-life effects on permissive live-weight thresholds

This study, based on the analysis of growth and reproductive records of 6158 young red deer hinds, tested the hypothesis that the nutritional environment in early life influences the permissive body mass threshold for puberty at around 16 months of age. Live-weight at 3 months (i.e. weaning weight) was a proxy for their nutritional environment between birth and weaning, live-weight at 14 months was the indicator of pre-mating body mass, and pregnancy status at 18-19 months was a proxy for entry into puberty. Data were obtained for two sub-populations of hinds, the commercial stud herds, across four consecutive years. The modelled relationships between pre-mating live-weight and the predicted pregnancy rate demonstrated between-year variation for the logistic curves for the commercial herd for the live-weight range from 50 to 90 kg (P<0.001). For the stud herd, the predicted pregnancy rate at any given live-weight did not vary significantly between years (P>0.05) and the pregnancy rates for live-weights <90 kg were higher than for the commercial herd. The regression of average weaning weight on probability of pregnancy showed significant positive associations (P<0.05) at 60 kg, 70 kg and 80 kg (R(2)=0.513, 0.517 and 0.439, respectively). There were no significant regressions at pre-joining live-weights at 90 kg or above (P>0.05). The study supports the central hypothesis of early-life influences on the permissive body mass threshold for entry into puberty.

Genetics of early conception and its relationship to growth traits in red deer (Cervus elaphus)

The genetics of early conception success and live-animal growth were studied in five herds of red deer in New Zealand. Conception date (CD) was used as the criterion of success in seasonally mated hinds, with 2493 mating records available. Liveweights analysed were weaning weight, yearling weight, 15-month weight and mature weight (hinds only). CD and liveweights were analysed using restricted maximum likelihood procedures with an animal model, including all available pedigree records. Under the management conditions applied, CD had a phenotypic standard deviation of 7.9 days, a repeatability across years of 0.29 ± 0.03 and a direct (univariate) heritability of 0.20 ± 0.06. Regression procedures using DNA markers to adjust the data for genetic differences resulting from an animal’s ancestral region of origin (mainly western vs eastern European) had little effect on the parameter estimates above. Direct heritability estimates for the four weight traits were 0.38 ± 0.03, 0.49 ± 0.02, 0.48 ± 0.04 and 0.46 ± 0.04, respectively, while the genetic correlations between CD and these traits (e.g. using 1763 paired records of CD with yearling weight) were –0.24 ± 0.11, –0.24 ± 0.09, –0.16 ± 0.10 and –0.04 ± 0.09, respectively. Selection for earlier CD would be successful and compatible with selection for higher juvenile weights.

Evaluation of management variables to advance conception and calving date of red deer (Cervus elaphus) in New Zealand venison production systems

The ability to shift the supply of New Zealand chilled venison from farmed yearling red deer stags to obtain premium prices in seasonal European markets necessitates early calving of hinds combined with high growth rates of their calves. Two studies over a three-year period evaluated three management variables that offer potential to advance calving date. Under the conditions of the studies there was no consistent evidence that the management practices of early stag introduction, early weaning and enhanced hind nutrition prior to conception (lactation) and pre-calving (third trimester of pregnancy) advanced conception date and calving date in red deer hinds. However, the nutrition effect was diminished by the difficultly in achieving the dietary contrast necessary for the targeted 5kg differentiation in hind live weight at strategic times of the year. Across all hinds there was a significant pre-mating (mid-March) live weight effect on conception day in the one year in which a 5kg difference between nutritional regimens was achieved, but the driver was live weight and not nutrition. There were significant effects of nutrition on calf growth, with the growth rates of calves weaned in mid-March significantly higher when their dams grazed a high plane of nutrition pre-conception. There were significant and consistent inverse relationships between conception day and calving date that implied variation around gestation length, with early- and late-conceiving hinds exhibiting longer and shorter gestation lengths, respectively. Across all treatments, calving date was predicted to advance by approximately 5 days for every 10-day advance in conception date. However, there was a significant carry-over effect of nutrition pre-conception on calving date, with hinds on a high plane of nutrition pre-conception exhibiting shorter (2-4 days) gestation lengths. There were also indications that hinds may manipulate gestation length in response to live weight gain pre-calving. These findings suggest that fetal growth trajectory may be the principle driver of gestation length and calving date. Although there were no direct effects of hind nutrition pre-mating on conception dates, nutrition remains an important component of the management of hinds and their calves in venison production systems. The outcomes of the 3-year program suggest that there are limited opportunities to manipulate calving date through manipulation of management variables.

The effect of conception date on gestation length of red deer (Cervus elaphus)

Recent studies have demonstrated that gestation length of red deer (Cervus elaphus) is highly variable and influenced by various environmental factors, and this may confer survival advantages for neonates. The current study investigated the relationship between conception date and gestation length to test the hypothesis that within-herd synchrony of red deer births is facilitated by a 'push/pull' control over gestation length, such that hinds conceiving early and late in the breeding season have longer and shorter gestation periods, respectively. In Study 1, data on conception and calving dates were obtained for 393 naturally cycling hinds across two herds. In Study 2, conception and calving dates were obtained from 91 hinds in which oestrus/conception were artificially synchronised across a 4-week range of dates spanning the natural rut. Gestation length for each population was analysed by linear regression, fitting conception day followed by terms for the fixed effect which included hind age (pubertal vs. adult), hind genotype (Cervus elaphus scoticus vs. Cervus elaphus hippelaphus and their crossbreds), calf sex, sire genotype (Study 1 only), birth weight and year. In Study 1, both populations of naturally cycling hinds exhibited highly significant (P<0.001) negative slopes (-0.36, -0.49) for the regression of gestation length against conception date, with indications of a significant hind genotype effect favouring shorter overall gestation lengths for crossbred hinds. Other effects for hind age, calf sex, birth weight, sire genotype and year were not significant. In Study 2, in which conception dates were artificially induced, there was a highly significant negative slope (-0.19), with a notable but non-significant effect of hind age favouring shorter overall gestation length for primiparous (pubertal) hinds (P>0.05). Other effects for hind live weight, calf sex and calf birth weight were not significant. All data sets support the hypothesis, and indicate that for every 10 days difference in conception date there was a change in gestation length of 1.9-4.9 days. This hints at the adaptive importance of optimisation of birth date in wild populations of red deer but the precise physiological mechanisms remain to be resolved. It is postulated that variation in fetal age during the latter stages of pregnancy, when feed quality and voluntary feed intake cycles are in a state of flux, may drive differential growth trajectories for early and late conceived fetuses, leading to nutritional control over fetal maturation and induction of parturition. However, consideration is also given to a putative direct effect of prevailing photoperiod on control of parturition processes in red deer.

Laparoscopic ovum pick-up and in vitro production of sika deer embryos: effect of season and culture conditions

Amongst the 200 deer subspecies worldwide, more than 40 are considered as endangered. In vitro embryo production may represent an efficient way to produce and disseminate offspring from sparse remaining individuals in these species. With a view to establishing a method of in vitro embryo production, we assessed the ovarian response after hormonal stimulation (oFSH), oocyte yield following laporoscopic ovum pick-up (LOPU) and oocyte developmental competence according to seasonal reproductive status in sika deer (Cervus nippon nippon). Twelve adult sika deer hinds were allocated between two groups and submitted weekly to oFSH follicular growth stimulation followed by LOPU. Hinds in Group A (n=6) were treated first during the breeding season (5 weeks), and then during the non-breeding season (3 weeks). Hinds in Group B (n=6) were submitted to similar procedures but in the reverse order (treated first during the non-breeding season). Cumulus-oocytes complexes (COC) recovered from Group B were allowed to mature in vitro for 24 h in TCM-199 medium supplemented with oFSH, goat follicular fluid and 100 microM cysteamine. In vitro fertilization was performed with frozen/thawed semen in SOFaa medium supplemented with 20% estrous sheep serum and presumptive zygotes were cultured in the presence or absence of ovine oviductal epithelial cell monolayer (oOEC) in SOFaa-BSA medium. Mean number of follicles aspirated per hind per session decreased significantly between breeding and non-breeding season in Group A (9.8+/-0.7 versus 3.2+/-0.7, mean+/-S.E.M., respectively, P<0.001) but did not change between the non-breeding and the subsequent breeding season in Group B (5.3+/-0.7 and 5.7+/-0.7, respectively, P>0.05). Irrespective of the season, good quality COC with complete and compact cumulus investments were recovered allowing a high cleavage rate after in vitro maturation and fertilization. Whereas development to the blastocyst stage did not occur in SOF medium alone, high development rates to the blastocyst stage were observed in oOEC co-culture regardless of season (22% and 34% of total oocytes in co-culture during non-breeding and breeding season, respectively).

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.

Handling during pregnancy in the blue fox (Alopex lagopus): the influence on the fetal gonadal function

In previous studies it has been shown that handling produced stress in pregnant blue fox vixens increasing plasma level and adrenal in vitro production of cortisol. Moreover, this treatment increased plasma cortisol levels in the fetuses. The present study was designed to examine effects of a 1-min daily handling stress applied to pregnant blue fox vixens on fetal gonadal steroidogenesis. Plasma concentrations of oestradiol and testosterone, gonadal content and gonadal in vitro production of these steroids, and response to exogenous hCG as well as gonadal weights, and anogenital distances were measured in control (C, n=69) and stressed (S, n=54) fetuses on 47-48 days of pregnancy. Maternal stress induced a suppression of gonadal steroidogenesis in the fetuses. The decreased testosterone content in the testes and oestradiol content in the ovaries were demonstrated in stressed fetuses compared with control (testosterone: 4.91+/-0.46 vs. 7.35+/-0.87 ng/both testes, P<0.05; oestradiol: 29.1+/-3.4 vs. 46.5+/-4.9 ng/both ovaries, P<0.05). The ovarian oestradiol in vitro production in female fetuses from stressed mothers was decreased in comparison with control (3.69+/-0.39 vs. 7.52+/-1.51 pg/ovary/h, P<0.05). The same difference was observed between stressed and control male fetuses in the testosterone testicular response to hCG (5.34+/-0.64 vs. 8.73+/-0.40 ng/testis/h, P<0.05). The ovarian weight from stressed fetuses was lower in comparison with control (12.9+/-0.7 vs. 16.8+/-0.6 mg, P<0.05). The anogenital distance in female fetuses from stressed vixens was also reduced (0.6+/-0.03 vs. 0.8+/-0.02 cm, P<0.01). These results indicate that prenatal stress resulted in a significant reduction of hormonal and morphometric measures of the reproductive system in blue fox fetuses with more drastic effects in female fetuses.

New developments reproductive technologies in deer

In vitro embryo production is the platform for advanced reproductive technologies, such as cloning. The in vitro embryo production system developed for farmed red deer (Cervus elaphus) evolved along similar lines to that pioneered by other domestic species researchers. However, applying existing in vitro embryo production methods from these other species resulted in limited success and has necessitated developing a species-specific methodology for red deer based on the their physiology. Analysis of oviduct fluid led to the development of a semi-defined fertilization and culture media system, Deer Synthetic Oviduct Fluid (DSOF), which resulted in successful culture of red deer embryos to the blastocyst stage. Transvaginal ultrasound-guided ovarian examination and ovum pickup has enabled the study of seasonality constraint and propagation from selected female genetics, respectively. During the 4-month breeding season (April-July), 15% of cleaved oocytes developed to blastocysts, whereas no blastocysts developed from oocytes collected after July. The process of developing an in vitro embryo production system for farmed red deer may serve as a beneficial model for the propagation of endangered cervine species.

Storage of semen and artificial insemination in deer

Methods of collection and freezing of semen of some deer species and aspects of controlled reproduction associated with the use of frozen-thawed semen by artificial insemination (AI) are discussed.

Genetic influences on reproduction of female red deer (Cervus elaphus) (1) seasonal luteal cyclicity

This study compared the onset and duration of the breeding season of female red deer (Cervus elaphus scoticus) and its hybrids with either wapiti (Cervus elaphus nelsoni) or Père David's (PD) deer (Elaphurus davidianus). In Trial 1 (1995), adult red deer (n=9), F1 hybrid wapiti x red deer (n=6) and maternal backcross hybrid PD deer x red deer (i.e., 14 PD; n=9) were maintained together in the presence of a vasectomised red deer stag for 12 months. They were blood-sampled daily or three times weekly so that concentration profiles of plasma progesterone could be used to identify the initiation, duration and cessation of luteal events. There was clear evidence of luteal cyclicity between April and September, with the transition into breeding associated with an apparent silent ovulation and short-lived corpus luteum (i.e., 6-12 days) in every hind. A significant genotype effect occurred in the mean time to first oestrus (P<0.05), with wapiti hybrids and 14 PD hybrids being 9 and 5 days earlier than red deer. Between six and nine oestrous cycles were exhibited by each hind, with no difference in mean cycle length (19.5-19.6 days) between genotypes (P0.10). The overall length of the breeding season was significantly longer for wapiti hybrids (143 days) than for either red deer (130 days) and 14 PD hybrids (132 days, P<0.05). In Trial 2 (1998), adult red deer (n=5), 14 PD hybrids (n=5) and F(1) PD x red deer hybrid (n=5) hinds were maintained together from mid-February (late anoestrus) to early May, in the presence of a fertile red deer stag from 1 April. Thrice-weekly blood sampling yielded plasma progesterone profiles indicative of the onset of the breeding season. Again, there was a significant genotype effect on the mean time to first oestrus (P<0. 05), with F(1) PD hybrids and 14 PD hybrids being 13 and 5 days earlier than red deer. However, conception dates were influenced by the timing of stag joining, and were not significantly different between genotypes. The results indicate genetic effects on reproductive seasonality. However, seasonality observed for PD x red deer hybrids more closely approximated that of red deer than PD deer.

Reproductive performance of farmed red deer (Cervus elaphus) in New Zealand. IV. Biological markers as risk factors for yearling and adult hind conception

A 2-year observational study of 15 red deer (Cervus elephus) farms was carried out in New Zealand from March 1992. In each year of study, approximately 1650 hinds were individually monitored for reproductive success. During farm visits in March 1992 and 1993, five yearling and five adult hinds per farm were randomly selected and blood sampled to define their haematological, biochemical and blood mineral profile. Faecal samples were taken for parasite egg and larvae count. Biological markers potentially affecting the probability of conception before May 1 or of conception that year were investigated separately using multivariable logistic regression analysis. Adult hinds with low serum phosphorus concentrations were more likely to conceive before May 1. Lower conception rates were observed in yearling hinds when blood glutathione peroxidase, serum vitamin B12, and serum albumin concentrations were low, and when faecal lungworm larval counts were high. While these associations have yet to be proven as causal, data suggests that monitoring and maintaining adequate blood elements, and controlling internal parasites in yearling hinds, may assist farmers to achieve optimum reproductive performance in farmed red deer herds.

Influence of social status on ovarian function in farmed red deer (Cervus elaphus)

This study examines the effects of behavioural and environmental factors on ovarian function in red deer hinds. Patterns of postovulatory luteal progesterone secretion were investigated in groups of farmed red deer hinds following oestrus induced by progesterone administration and withdrawal. Hinds were held under conditions leading to low (Experiment 1, held in paddocks: 0.29 per animal/h) or high (Experiment 2, held in pens: 1.11 per animal/h) interaction rates, and progesterone was measured in jugular venous blood samples obtained daily for 14 days after ovulation. Plasma progesterone levels tended to differ with respect to dominance status in both experiments (p < 0.1). Progesterone levels were substantially lower following prolonged hot dry weather (mean 0.67 +/- SEM 0.03 ng/mL) than in a year of relatively typical climatic conditions (mean 1.63 +/- 0.04 ng/mL; p < 0.0005). Progesterone levels were not related to the body weight of the hinds, and were not affected by housing conditions leading to different interaction rates. We conclude that although there is a tendency for dominance status to affect ovarian function, as observed before, this relationship is obscured in farmed red deer where all animals in the herd enjoy a higher plane of nutrition and movements of individuals between groups confuse dominance relationships.