Red Deer Hinds Research Articles

Genetic influences on reproduction of female red deer (Cervus elaphus) (2) seasonal and genetic effects on the superovulatory response to exogenous FSH.

This study evaluated the influences of seasons and genotype on the superovulatory response to a standardised oFSH regimen in red deer (Cervus elaphus scoticus) and its hybrids with either wapiti (C.e. nelsoni) or Père David's (PD) deer (Elaphurus davidianus). Adult red deer (n=9), F(1) hybrid wapiti x red deer (n=6), and maternal backcross hybrid PD x red deer (i.e., 14 PD hybrid; n=9) were kept together in the presence of a vasectomised stag for 13 months. At 6 weekly intervals, all hinds received a standardised treatment regimen used routinely to induce a superovulatory response in red deer hinds, with 10 consecutive treatments spanning an entire year. This involved synchronisation with intravaginal progesterone devices and delivery of multiple injections of oFSH (equivalent to 72 units NIH-FSH-S(1)). Laparoscopy to assess ovarian response was performed 6-7 days after the removal of the devices. Both season and genotype had significant effects on ovulation rate (OR) and total follicular stimulation (TFS) (P<0.05). For all the three genotypes, ovarian responses were highest from March to November (breeding season) and lowest in the period from December to January, inclusive. Mean OR for red deer hinds ranged from 3.7 to 1.8 during the breeding season, with no observable trend. All red deer hinds were anovulatory during December and January. A similar pattern occurred for 14 PD hybrids, although mean OR during the breeding seasons were twofold lower than for the red deer. For F(1) wapiti hybrids, the first two treatments in March and April resulted in the highest mean OR observed (15.6 and 11.7, respectively). Thereafter, mean values ranged between 6.3 and 4.7 for the remainder of the breeding season. Furthermore, mean OR of 3.0 and 0.5 were recorded in December and January, respectively. For the red deer and F(1) wapiti hybrids, between-hind variation in OR was not randomly distributed across the treatment dates, indicating that the individuals varied significantly in their ability to respond to oFSH, at least within a given season.In conclusion, the study has shown that relative to red deer, F(1) wapiti hybrid hinds exhibit a higher sensitivity to oFSH, whereas 14 PD hybrid hinds have a lower sensitivity. However, individual variation within genotype was very marked. A seasonal effect was apparent for all genotypes, although some F(1) wapiti hybrid hinds exhibited ovulatory responses throughout the year.

Milk production and composition in captive Iberian red deer (Cervus elaphus hispanicus): effect of birth date.

This study describes milk production and milk composition of Iberian red deer (Cervus elaphus hispanicus) females (hinds) and the effect of calving date and BW change of hinds by milking over 34 wk. All hinds produced milk throughout the 34-wk study period, well over the standard lactation period. Total milk yield was 224.1 +/- 21.1 L, and daily production was 0.91 +/- 0.06 L. Milk yield decreased with lactation stage (P = 0.01) and the later a calf was born (P = 0.008), and it was greater in posterior quarters (P < 0.05). Milk yield was unaffected (P > 0.10) by side position or milking order of the udder. Milk production did not correlate with hind BW (P > 0.1). Hinds lost 4.4% BW during lactation (P < 0.001); losses increased the later a calf was born (P = 0.012). Iberian red deer milk had 11.5% fat, 7.6% protein, 5.9% lactose, and 26.7% DM. Stage of lactation affected fat (P < 0.001), protein (P = 0.002), DM (P < 0.001), and protein:fat ratio (P < 0.001), but not lactose (P > 0.1). These constituents became concentrated as lactation proceeded, and protein was substituted by fat. Calving date had a similar concentrating effect on fat (P < 0.001) and DM (P < 0.001), whereas it decreased lactose (P = 0.015) and protein (P = 0.002), thus producing a substitution of protein by fat (ratio of protein to fat, P < 0.001). Milking order of quarters or their position had no effect on milk composition (P > 0.10). Results suggest that milk production and milk energetic quality might increase by advancing calving date in red deer hinds.

The relationship between habitat choice and lifetime reproductive success in female red deer.

In non-territorial species, individuals can move freely and should be distributed in an ideal free manner between habitats and areas with respect to resources that influence lifetime reproductive success (LRS). Consequently, no relationship between diet quality and LRS should be expected. However, there have been no attempts to test this prediction. The present paper investigates the relationship between forage habitat use and LRS in red deer (Cervus elaphus) hinds within three neighbouring areas on the Isle of Rum which differed in their amounts of high-quality-forage habitat. Within areas, hinds move widely and have access to the same resources. We found no correlation between LRS of individual hinds and their use of high-quality-forage habitat (i.e. short Agrostis/Festuca grassland). Our analysis suggests that high hind densities on short Agrostis/Festuca grassland offset any advantages of increased access to preferred forage. These results support the hypothesis that red deer hinds are distributed in an ideal free manner with respect to the use of high-quality-forage habitat. However, hinds rarely leave areas where they are born, and the analysis suggests that constraints in changing areas hindered an ideal free distribution on a larger spatial scale. Consequently, mean LRS was not the same within the three investigated areas: one area, with a low amount of short Agrostis/Festuca grassland and a low hind density, contributed more male offspring (and more total offspring) per hind to the population than the other two areas.

Source and site of action of anti-luteolytic interferon in red deer (Cervus elaphus): possible involvement of extra-ovarian oxytocin secretion in maternal recognition of pregnancy.

Six conceptuses were collected from red deer hinds on day 22 after synchronization of oestrus with intravaginal progesterone-releasing devices (removal of device = day 0). Within 24 h of culture in vitro, the supernatant from five of six conceptuses showed detectable antiviral activity. Interferon alpha (IFN-alpha) receptors were identified by immunohistochemistry on the luminal surface of the endometrium, in the neurohypophysis and paraventricular hypothalamus, but not in the ovaries of the hinds from which the conceptuses were collected. Another 16 intact hinds were synchronized as above. Injection of 4 mg IFN i.m. twice a day on days 13-15 had no effect on cloprostenol-induced oxytocin secretion on day 15 and did not prevent cloprostenol-induced luteal regression. Sixteen ovariectomized hinds received a protocol of steroid treatment to mimic ovarian hormone secretion during the normal oestrous cycle. On day 16, hinds showed undulant oxytocin secretion that showed a degree of temporal association with uterine PGF2 alpha release. Treatment with 4 mg IFN-alpha I 1 twice a day on days 13-16 had no effect on this spontaneous oxytocin secretion, but reduced the magnitude of cloprostenol-induced oxytocin secretion on day 17 (P < 0.05). These results indicate that red deer conceptuses secrete an anti-luteolytic IFN to which the endometrium expresses a receptor during early pregnancy. The presence of IFN receptors in the hypothalamus and posterior pituitary and the IFN-induced suppression of extra-ovarian oxytocin secretion provides tentative evidence of an involvement of the central nervous system in maternal recognition of pregnancy in deer.

Successful in vitro fertilization of in vivo matured oocytes aspirated laparoscopically from red deer hinds ( [formula omitted

Most current protocols of in vitro fertilization in ruminants are based on in vitro maturation of oocytes derived from abattoir material. For application of IVF technology to captive endangered species, however, noninvasive techniques are required which allow repeated collection of oocytes from live females. The aim of this study was to develop a method for embryo production from mature oocytes collected laparoscopically from red deer hinds. Follicular development was synchronized in red deer hinds by the insertion of intravaginal progesterone-releasing devices for 10 d, and ovarian stimulation was induced with 1000 IU, im PMSG 48 h before progesterone device removal. Oocytes were harvested by laparoscopy under xylazine/ketamine sedation 24 h after progesterone device removal and then co-incubated with frozen-thawed red deer spermatozoa for 24 h. In Experiment 1, oocytes and embryos were fixed and stained at different developmental timepoints. Their external morphological changes (cumulus expansion, extrusion of the second polar body and cytokinesis) paralleled their nuclear developmental changes (formation of the 2nd metaphase spindle of meiosis, pronuclear formation and nuclear division, respectively). In Experiment 2, embryos were maintained in vitro until they ceased to undergo cell division. A total of 39 aspiration procedures was carried out on 14 red deer hinds. Forty-four cumulus-oocyte complexes (COC) were aspirated from 95 large Graafian follicles; of these, 27 were classed as mature/nondegenerated on the basis of cumulus/cytoplasmic morphology. Seventeen oocytes cleaved following in vitro fertilization, yielding six 2-cell embryos, six 4-cell embryos, four 8-cell embryos and one 16-cell embryo. The results indicate that laparoscopic aspiration of mature oocytes from hormone-treated females offers a valuable source of genetic material for assisted deer breeding programs.

Effects of mixed-species stocking and space allowance on the behaviour and growth of red deer hinds and ewes at pasture

Our objective was to test whether the effects of space allowance on social interactions, activity patterns and growth rates of hinds reared at pasture in single-species groups, were modified by mixing them with ewes. Thirty individuals of each species were assigned to two single-species groups of 10 animals (hinds: H1 and H2, ewes: E1 and E2) and to two mixed-species groups of 5 hinds and 5 ewes (M1 and M2). For 28 days, H1, E1 and M1 were kept at high space allowance (HSA: 267 m 2/animal) and H2, E2 and M2 at low space allowance (LSA: 67 m 2/animal) and for the following 28 days, the space allowance was reversed. Mean interindividual distances in single-species groups were lower at LSA than at HSA (hinds: 10.0±0.3 vs. 15.4±4.8 m, P<0.05; ewes: 7.9±0.5 vs. 11.0±2.5 m, NS). In mixed-species groups, distances between standing individuals of the same species were less than between individuals of a different species (hinds: 8.8±1.6 vs. 11.0±1.0 m, NS; ewes: 5.3±1.1 vs. 7.5±2.3 m, NS; hinds-ewes: 14.6±0.9 vs. 20.6±1.0, P<0.05, at LSA and HSA, respectively). Agonistic encounters between hinds were more frequent at LSA than at HSA when reared in single-species groups (median number of agonistic interactions/hour: 10.0 (9.6–12.8) vs. 5.0 (1.9–11.6), P<0.05). When reared in single-species groups, hinds were less synchronised during grazing at LSA than at HSA and they had shorter and more frequent meals. Such effects were not observed for ewes. Rearing the animals in mixed-species groups increased the effects of a restricted space allowance on grazing meals of hinds with a tendency to increase the number of meals and to reduce meal duration. In mixed-species groups, the effect of space allowance on ewes was more marked than when in single-species groups with ewes eating shorter and more frequent meals. The hinds reared in single-species groups grew slower at LSA than at HSA (185±63 vs. 225±42 g/day, P<0.01), whereas ewes grew at the same rates regardless of space allowance (175±53 vs. 185±54 g/day, at LSA and HSA, respectively, NS). In mixed-species groups, growth of both hinds and ewes was lower when space was restricted (hinds: 141±42 vs. 211±56 g/day, ewes: 170±47 vs. 202±32 g/day, at LSA and HSA, respectively, all P<0.05). In conclusion, restricting the space allowance resulted in behavioural changes and lower performance which were intensified by mixed-species stocking.

Involvement of serotoninergic pathways in the control of luteinizing hormone secretion in red deer hinds.

Two experiments were conducted to determine whether serotoninergic pathways, which are implicated in the neuroendocrine regulation of luteininzing hormone (LH) secretion in domestic animals, have a similar action in red deer hinds. In the non-breeding season (August), ovariectomized (n = 5) and ovariectomized-thyroidectomized (n = 5) hinds received a vehicle solution followed 4 h later by either serotonin (66 microg kg(-1) i.v.) every 10 min for a further 4 h or the serotonin antagonist, cyproheptadine (3 mg kg(-1) i.v.) as a single injection. This procedure was repeated in the breeding season (June). In the non-breeding season serotonin was without effect, but cyproheptadine reduced LH pulse frequency and amplitude in ovariectomized-thyroidectomized hinds (P<0.01). During the breeding season, serotonin reduced LH pulse amplitude in ovariectomized hinds (P<0.05) and cyproheptadine reduced LH pulse frequency in both ovariectomized and ovariectomized-thyroidectomized hinds (P<0.05 and P<0.01, respectively). On each occasion, cyproheptadine increased (P<0.01) plasma prolactin concentration, whereas serotonin had no effect. These results indicate a stimulatory role for serotoninergic neurons on the hypothalamic GnRH pulse generator mechanism of red deer hinds during the breeding season. In a second experiment, the LH response to GnRH (5 microg i.v.) was examined in ovariectomized hinds (n = 5) following administration of a serotonin infusion (6.6 microg kg(-1) min(-1) i.v. for 15 min), cyproheptadine (3 mg kg(-1) i.v. as a single dose) or vehicle, in the breeding season (July) after induction of halothane anaesthesia and in the non-breeding season (December) without anaesthesia. Halothane anaesthesia eliminated endogenous pulses of LH. In comparison with the vehicle-treated controls, the response of plasma LH to exogenous GnRH was not altered by serotonin or cyproheptadine in either season, which shows that serotonin has no effect on LH release at the pituitary gland level in these animals. It was concluded that in the regulation of LH release in red deer hinds, serotoninergic pathways have a stimulatory role operating at the hypothalamic level.

Lactation curves in captive Iberian red deer (Cervus elaphus hispanicus).

This study examines milk production and the effect of milk production and sex of calf on body weights and gains of red deer calves and hinds of the Iberian subspecies (Cervus elaphus hispanicus). Milk production was assessed in 14 hinds by weighing calves before and after suckling and by adjusting these values to the Gamma function. Gamma estimates of total milk production up to d 105 were similar to the amounts computed directly from double weighing. Hinds showed two types of lactation curve: 1) the standard mammal lactation curve, with an asymmetrical peak at wk 2 to 4 (Type I) and 2) decreasing curves with no peak (Type II). Although there was great interindividual variability, hinds with Type I curves showed a trend to produce more milk than those with Type II. The type of curve did not seem to affect weight variables of the calf or those of the dam. Calves that gained more weight consumed greater amounts of milk (P<.05). Males were heavier than females at birth (P<.05), but males did not differ from females in their weight at 105 d, milk consumption, and gain. Gender did not affect hind weight, but dams of male calves showed a trend to be lighter (P = .063) at d 105 than dams of female calves. Our results suggest that suckling differences found in other studies between male and female calves may not involve differences in milk production, although other rearing costs seem to affect hind weight losses. They also suggest that the curve type may not depend only, as reported, on the nutrition plane.

A body condition score system and its use for farmed red deer hinds

A longitudinal observational study of 15 red deer farms in New Zealand was carried out for a 2‐year period. To assess the body condition of deer, a scoring chart was developed with scores ranging from 1 (lean) to 5 (fat) with half‐unit increments. Scores were given after palpating the tuber coxae, sacrum, and rump area of the deer standing straight and quiet. Repeatability and reproducibility were evaluated on 39 yearling hinds and 90 adult hinds on four properties which were independently scored twice by two assessors to investigate assessor bias and consistency. A body condition score (BCS) was assigned to 1400 and 2100 hinds in consecutive years in March before mating, in September before calving, and in March of the next year at weaning. There were wide variations of individual hind body condition and mean hind body condition between farms. Overall, yearling hinds lost body condition during winter and subsequently during lactation up to weaning. Repeatability and reproducibility were above 0.8. There was variability between assessors confirming the need for training when more than one assessor is involved. It is proposed that the condition scoring chart presented here should be adopted industrywide as a tool for the management of breeding hinds to achieve optimum reproductive performance, since BCS was significantly associated with conception rate, conception date, dystocia, weight of weaned offspring, and ability of the hind to rear a calf to weaning. A management plan for the use of this body condition scoring system is proposed.

Pulsatile luteinizing hormone secretion in the ovariectomized, thyroidectomized red deer hind following treatment with dopaminergic and opioidergic agonists and antagonists.

Two experiments were conducted to determine whether dopaminergic or opioidergic pathways are modulated by thyroid gland secretions for seasonal suppression of LH secretion in red deer hinds. Ovariectomized (n = 5) or ovariectomized and thyroidectomized (n = 4) hinds, treated with estradiol implants, received the dopamine agonist bromocriptine or the antagonist sulpiride during pulse bleeds in July (breeding season) and October (nonbreeding season). Comparison of July and October mean plasma LH concentration (3.5 +/- 1.3, 0.7 +/- 0.1 ng/ml, respectively), pulse frequency (1.9 +/- 0.4, 0.7 +/- 0.2 pulses/4 h), and pulse amplitude (1.3 +/- 0.5, 0.7 +/- 0. 02 ng/ml) showed lower (p < 0.05) levels in October, and these levels were not significantly affected by thyroidectomy or drug treatment. In the absence of estradiol implants, the hinds received bromocriptine or morphine during the breeding season (July) and their antagonists, sulpiride or naloxone, respectively, in the nonbreeding season (November). In euthyroid hinds there was a seasonal decrease (p < 0.05) in mean plasma LH concentration, pulse frequency, and pulse amplitude, which did not occur in thyroidectomized hinds. There were no effects of drug treatment on LH concentration except for a small increase following sulpiride in November. Plasma prolactin concentration was significantly increased by antagonists and decreased by agonists on most occasions. We conclude that in red deer hinds, seasonal regulation of LH secretion does not involve dopamine or endogenous opioids and the thyroid gland is required specifically for LH suppression in the absence of estradiol.

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.

Evaluation of Lotus corniculatus for increasing pre-weaning growth of red and hybrid deer

Lactating red deer (Cervus elaphus) hinds and their calves were rotationally grazed on Lotus corniculatus or perennial ryegrass/white clover pasture at an allowance of 12 kg DM/hind/day during summer 1996 in Palmerston North, New Zealand. Half the hinds suckled pure red deer calves and half suckled hybrid (0·25 elk[ratio ]0·75 red deer) calves. Measurements were made of the diet selected, voluntary feed intake of the hinds and liveweight changes of the hinds and calves.Lotus corniculatus and perennial ryegrass constituted c. 90% of green material in the diet selected on the respective forages. Total nitrogen (N) content and organic matter digestibility (OMD) were higher for Lotus corniculatus than for perennial ryegrass/white clover pasture. Lotus corniculatus contained 21 g condensed tannin (CT)/kg dry matter (DM), whilst pasture contained only traces of CT (1·6 g/kg DM).Hinds grazing Lotus corniculatus tended to have higher voluntary feed intake, and calf liveweight gain (485 v. 399 g/day) and weaning weight (52·6 v. 48·1 kg) were greater than for deer grazing perennial ryegrass/white clover pasture. Hybrid calves grew faster than pure red deer calves (P&lt;0·01), with hybrid calves grazing lotus having very high liveweight gain (c. 520 g/day). Liveweight gain of hinds grazing Lotus corniculatus also tended to be higher (91 v. 20 g/day) than for hinds grazing perennial ryegrass/white clover pasture. CT was bound more strongly during chewing by red deer than had been found in comparable studies with sheep and the nutritional significance of this is discussed. Nutritional reasons for the superior performance of deer grazing Lotus corniculatus are discussed.

Estimation of energy expenditure in free-living red deer (Cervus elaphus) with the doubly-labelled water method

Energy expenditure was estimated using the doubly-labelled water (DLW) method in summer in five free-living adult, non-pregnant, non-lactating, red deer (Cervus elaphus) hinds (weight 107.3 (SE 0.9) kg; age 6 (SE 1) years) on lowland pasture under typical farming conditions. Climatic conditions were monitored throughout the experiment. Errors due to 2H losses in CH4 and faeces were calculated from previous estimates of stoichiometries. CH4 production, fractionated water loss, urinary N and O2 consumption were estimated using an iterative approach. The water flux (rH2O) in these animals consuming only fresh grass was 12 (SE 0.5) kg/d, the CO2 production (rCO2) was 1271 (SE 40) litres/d and the mean energy expenditure was 25 (SE 0.8) MJ/d. There were no significant differences in the isotope distribution spaces and flux rates, rH2O, rCO2 or energy expenditure using the multi-point or two-point approaches to calculation. The DLW-derived energy expenditure of 25 MJ/d is approximately 20% higher than the recommended intake of 21 MJ/d for adult hinds kept outdoors (Adam, 1986) and, at 757 kJ/kg0.75 per d, one third higher than the value of 570 kJ/kg0.75 per d for stags penned indoors (Key et al. 1984).

Fence Line Pacing in Farmed Red Deer Hinds at Calving

AbstractThe frequency, intensity and location of fence line pacing were observed daily, in four groups of six farmed red deer hinds, over a 3-week period at calving. The groups were confined in neighbouring paddocks (5000m2 in area; two containing a wooden shelter) adjacent to deer yards containing an observation hide. At 1100h, a person entered each paddock to weigh, sex and tag newborn calves.Pacing (moving parallel to and within 0.5m of a fence line) was mainly at walking speed, and its frequency differed according to the time relative to parturition. It was recorded in 13.6 (± 1.09) per cent of observations during the period 2-4 to days before calving, increased to 27.6 (± 1.9)per cent on the day before birth and then declined to 4.6 (± 0.39) per cent for the period of 0-3 days after calving. Pacing relative to total movement was greater before (65.7%) than after (43.5%) parturition (SED 3.7%; P &lt; 0.001), indicating that it was not just a consequence of greater activity before birth. The hinds were observed to be grouped together rather than distributed randomly, but when some of the hinds were pacing, groups were spread out over more quarters of the paddock than when none were pacing (P &lt; 0.001). However, there was no definite suggestion of avoidance of other deer. Within each group, most pacing occurred along certain fence lines, but no general pattern was observed. Regardless of whether hinds had given birth or not, there were graded increases in pacing depending on the degree of human presence (not present&lt;within deer yards &lt;visible&lt;in paddock; P &lt; 0.05); and deer favoured areas distant from human presence (P &lt; 0.01). The findings in relation to fence line pacing and location support suggestions that human interference at calving should be minimized, but did not indicate which environmental features were responsible for this motivational drive.

Effect of method of blood sample collection on adrenal activity in farmed red deer and sheep following administration of ACTH

AbstractThe effect of method of blood sample collection (automatic blood sampling equipment (ABSE) v. manual) on cortisol and progesterone concentrations was investigated in 20 farmed red deer hinds and 20 domestic sheep ewes following dexamethasone and exogenous ACTH administration. Ten animals were subjected to either automatic sampling or manual sampling via jugular venipuncture in 1 week, with the treatment groups reversed in the 2nd week. The ABSE was programmed to collect a blood sample, then deliver 2 mg dexamethasone, collect a further blood sample 120 min later and then inject 100 fig ACTH. Thereafter, samples were collected at 15-min intervals during a 2·5 h period (12 samples in total). In the manual injection and sampling treatment, four samples were collected: (1) before dexamethasone administration, (2) before ACTH administration, (3) 60 min after ACTH administration, and (4) 150 min after ACTH administration. The success rate of blood sampling with ABSE was 80%. The overall mean packed cell volume (PCV) from samples collected by ABSE from both hinds and ewes was significantly lower than that from samples collected manually (P &lt; 0·01) and PCV declined with time in manually sampled animals (P &lt; 0·01). Plasma cortisol concentrations peaked at 45 min after ACTH administration in sheep and deer. In sheep, there was a marked fluctuation in the plasma cortisol concentrations with time. Both deer and sheep showed a reduced cortisol response to ACTH during week 2 irrespective of sampling method suggesting down-regulation of the response to ACTH. Maximum mean plasma progesterone concentration was reached at 15 to 30 min after ACTH administration. No significant differences in cortisol and progesterone responses due to blood sampling method were found in animals receiving prior dexamethasone treatment. This demonstrates that the ABSE has the ability to be used to effectively conduct ACTH stimulation tests without the need to handle the animals during the test.

Effects of thyroidectomy and thyroxine replacement on seasonal reproduction in the red deer hind.

Two experiments were conducted to test whether thyroid hormones are required for the cessation of the breeding season in female red deer. In Expt 1, 16 mature hinds were allocated early in the breeding season (May) to the following groups: thyroidectomized (THX), thyroidectomized and treated with subcutaneous thyroxine implants which increased plasma tri-iodothyronine to physiological concentrations (THX + T4), or euthyroid controls. Plasma progesterone concentrations consistent with oestrous cyclicity were evident in all hinds during the breeding season (May-September) but after 23 September plasma progesterone concentrations became generally low (< 2.0 nmol l-1) in control and THX + T4 hinds. In contrast, thyroidectomized hinds not receiving thyroxine continued to exhibit circulating progesterone comparable with breeding season concentrations until the end of the experiment (late December). Nine hinds were ovariectomized or ovariectomized and thyroidectomized in May and treated with subcutaneous oestradiol-impregnated capsules, which were removed for periods of about 1 months during August, November and January, to test whether thyroid hormones are involved in the seasonal decline of LH secretion (Expt 2). In the presence of oestradiol, basal LH concentrations and episodic LH secretion were low during the non-breeding season (September-March) (P < 0.05). During this season, basal and GnRH-induced LH concentrations and LH pulse frequency remained similar for both groups except in the absence of oestradiol, when basal LH (3.1 +/- 0.8 versus 1.3 +/- 0.5 ng ml-1, P < 0.05 and GnRH-induced LH (25.9 +/- 3.6 versus 4.7 +/- 0.4 ng ml-1, P < 0.001) concentrations were higher in thyroidectomized hinds than in euthyroid hinds, respectively. Twenty-five hinds were ovariectomized and thyroidectomized during the breeding season and treated with subcutaneous thyroxine implants at different times to identify when thyroid hormones are required to be present to suppress LH concentrations during the non-breeding season in the absence of oestradiol. Thyroxine treatment at the beginning of or during the non-breeding season was effective in suppressing plasma LH concentration, but this action of thyroid hormones did not occur during the breeding season. These results indicate that, in red deer hinds thyroxine is required for termination of the breeding season and that thyroid gland secretions specifically block steroid-independent inhibition of reproductive activity during the non-breeding season. This inhibitory mechanism requires thyroid hormones to be present only from around the time of the end of the breeding season for their normal expression, and they remain responsive to thyroid hormones after this period.

The effect of previous browsing damage on the morphology and chemical composition of Sitka spruce ( Picea sitchensis) saplings and on their subsequent susceptibility to browsing by red deer ( Cervus elaphus)

Three year-old Sitka spruce saplings, which had received one of two levels of fertiliser addition (high or low) in one year, were either browsed by red deer or left undamaged in a subsequent year. After a further year of growth, the selection and browsing behaviour of red deer on damaged and undamaged trees were studied in a controlled experiment. Morphological and chemical analysis of ten trees from each treatment combination showed that damaged trees were significantly smaller after one year than undamaged trees but had longer needles. Chemical composition was not affected by browsing. High fertiliser addition increased most size parameters and increased the nutritive value of trees. The preference for previously damaged and undamaged trees was compared in a series of thirty two trials. On eight separate occasions, four red deer hinds were individually offered the choice of two damaged and two undamaged trees in an experimental enclosure. During each trial, biomass removed, number of bites removed, duration of browsing, intake rate, and mean bite weight at each tree were recorded. Biomass removed, bites taken and time spent at trees were significantly greater for previously undamaged trees than for damaged trees. All three variables were also positively related to the height of each tree and the number of lateral branches on each tree. The greater foraging effort on undamaged trees was not fully accounted for by the morphology of trees or their chemical composition. It is suggested that increased needle length caused animals to stop feeding sooner and hence led to less browsing damage in previously damaged trees. The results imply that previously observed localised browsing damage in forestry plantations is unlikely to be the result of changes to the plant induced by previous browsing damage.

Effects of stocking density on the behaviour and growth of farmed red deer hinds

The aim of this experiment was to measure the effects of stocking density on the social behaviour, activity patterns and growth rates of yearling red deer hinds reared at pasture. Twenty individuals were assigned to two groups of 10 in a latin square design. During period 1 (28 days), group 1 was kept at a low stocking density (LD: 37 animals/ha) and group 2 at a high stocking density (HD: 150 animals/ha). During period 2 (28 days) the groups were switched and tested at the other stocking density. Aggressive encounters (kicks, bites and butts) and vigilance postures were more frequent at HD than at LD. There was no difference between the two densities in the total time spent grazing per day, but the hinds at HD had shorter and more frequent meals than the hinds at LD. The synchronisation of grazing was also lower at HD than at LD. The hinds grew faster at LD than at HD. The effects of stocking density on growth and grazing behaviour were more severe for subordinate than for dominant hinds. In conclusion, high stocking density induced a social stress that affected grazing patterns and growth rates, especially in subordinate individuals.

Effects of Winter Housing, Exercise, and Dietary Treatments on the Behaviour and Welfare of Red Deer (Cervus Elaphus) Hinds

AbstractTo assess the welfare of red deer (Cervus elaphus) confined at pasture or in indoor housing over winter, behaviour, productivity, skin damage and adrenal response to ACTH challenge were measured in six groups of eight weaner hinds over 91 days from June to September 1990 in Otago, New Zealand. The hinds were confined either indoors (I), indoors with daily exercise (IE), or outdoors (O); (n - 2 groups to each treatment). All groups were fed concentrate ad libitum plus 100g lucerne head−1 day−1.Indoor confinement was associated with a greater incidence of nosing/chewing other hinds, aggression, chewing of the enclosure, and closer distances between individuals, compared with outdoor confinement (P &lt; 0.05). Ad libitum provision of hay over a 2-week period reduced the incidence of chewing of indoor enclosures (P &lt;0.01). Weight gain was greater for indoor groups than outdoor groups in August and September (P &lt;0.05) and overall weight gains for indoor groups (from two weeks into the study, until the end) were higher for the exercise treatment (P &lt;0.05). Intake of concentrates did not differ significantly between treatments. Skin damage was greater for indoor than outdoor groups (P &lt;0.05), and positively related to weight gain (P &lt;0.01) and receiving aggression (P &lt;0.01), which in turn was negatively related to liveweight (P &lt; 0.001). A negative relationship was found between pre-challenge levels of plasma Cortisol and the number of aggressive interactions received (P &lt; 0.05). Pre-challenge Cortisol was greater for IE than I (P &lt; 0.05), and the increase in Cortisol post-challenge was greater for outdoor groups than indoor groups (P &lt;0.01). Conclusions were that indoor confinement had a positive effect on weight gain, but increased aggression and skin damage, indicating that the deer were compromised socially. Provision of ample forage reduced chewing of the walls. The slightly greater weight gain in IE compared with I deserves further investigation.

Growth responses in red deer hinds from 16-24 months of age when fed two energy levels during their second winter

It is important that venison competes with other red meats in efficiency and cost of production. The growth responses of farmed red deer during the first 15-18 months of life have been well defined under a wide range of feeding and daylength regimes (Davies, 1995). However there is a need to examine less intensive systems of production which aim to maximise growth from grazed grass, following various growth-restriction feeding regimes during winter. The objective of this experiment was to quantify the growth response in 16-24 month old hinds fed two contrasting feeding regimes during their second winter, followed by a period at pasture.