Red Deer Hinds Research Articles

The effect of season on in vitro degradability and fermentability of feeds in red deers’ (Cervus elaphus L.) rumen fluid

Transition from summer to winter changes red deer digestive tract physiology and digestive processes. The objective of the trial was to determine the effects of season on in vitro apparent (ivADMD) and true dry matter (ivTDMD) digestibility, in vitro gas production parameters and short-chain fatty acid synthesis (SCFA) in red deer hinds of eleven substrates naturally occurring in Slovenia (chestnut fruits, acorns of common and sessile oak, two fresh grasses) and those frequently used in supplemental red deer feeding (two grass hays and two grass silages, apple pomace and sugar beet roots). There were no differences in ivADMD, ivTDMD, determined by incubation of feeds in buffered rumen fluid, as there were no differences in majority of gas production parameters between autumn and winter season. Only the parameter “C” (specific gas production rate) was frequently higher (p < 0.05) in winter season than in autumn season. The amounts of SCFA were similar between two seasons. However, the proportion of acetic acid tended to be higher in winter, while the proportions of propionic and butyric acid tended to be higher in autumn than in winter especially in high fibre feeds. On contrary, in high starch feeds such as oak acorns and chestnut fruits, the proportion of propionic acid was higher (p < 0.05) in winter, while of butyric acid in autumn (p < 0.05). Despite the fact that the number of used substrates (n = 11) and animal rumen fluid donors (n = 6) were small, these results indicate a shift in rumen microbial metabolism between autumn and winter season.

The use of GPS data to assess behaviour of red deer hinds over calving: hinds farmed in extensive high-country environments

ABSTRACT Global Positioning System (GPS) technology was used to track movements of extensively farmed red deer hinds over the calving period on two New Zealand high-country farms, during the summers of 2006/07, 2007/08 (Haycocks Station) and 2008/09 (White Rock Station). The goal was to analyse positional data around the expected birthing period to define patterns of hind movement that are potentially descriptive of parturient behaviour. A Hidden Markov model (HMM) was used to identify the time and site of calving based on four pre-defined stages of behaviour described for red deer hinds. These stages are: Late pregnancy (State 1), birth-site searching (State 2), birthing (State 3) and post-birthing (State 4). Previous research on red deer hinds over calving on an intensive lowland farm showed a close alignment between actual calving behaviour and those behaviours inferred from the algorithms developed in the HMM. Hinds in the high-country study conformed to the four-stage model of positional movement patterns. Inferred birthing dates ranged from 8 Nov to 3 Dec. The length of time hinds spent searching for a birthing site (State 2) was highly variable and averaged 16 (SE 3.9) hours, with an average 4-fold increase in distance between consecutive GPS recordings relative to that occurring earlier in late pregnancy (State 1), while in the birthing stage (State 3) there was a 40% reduction in distance between recordings compared with State 1. Although actual incidences of birthing were not observable in this study, it is concluded that definable behavioural characteristics of red deer hinds over the calving period can be discerned from GPS positional data. A key observation of this study was the between-hind variability of duration of these innate behaviours that indicates behavioural plasticity in the face of intraspecific competition for resources or perception of threat within extensive farm environments.

Neospora caninum and Toxoplasma gondii infections and their relationship with reproductive losses in farmed red deer (Cervus elaphus).

The aims of the present study were to determine the Neospora caninum and Toxoplasma gondii seropositivity rates in farmed red deer hinds from Argentina and their relationship with reproductive losses. Over a 2-year period, 449 hinds from 4 commercial farms were serologically tested at late gestation for N. caninum and T. gondii by IFAT. During the first year, a sequential serological analysis was carried out at 3 different time points to analyze antibody dynamics from mating until the end of the gestation period. Fetal and postnatal mortality rates were estimated by 3 successive ultrasound scannings (us) annually and a breeding control carried out after the calving period. Ultrasound fetal measurements were used to estimate conception date and gestational age of abortions. The seropositivity rate for N. caninum was 25.5% (37/145) for the yearlings and 34.2% (104/304) for the adults, while for T. gondii was 64.3% (93/145) and 78.3% (238/304), respectively. Abortions detected at us1 and us2 were 13/21 (61.9%) with a range of gestational age of 30-87 days, while abortions detected at us3 were 8/21 (38.1%) with a range of gestational age of 49-209 days. The fetal mortality rate was 4% and 5.8%, while the postnatal mortality rate was 18.8% and 4.1% of 101 yearlings and 294 adult pregnant hinds, respectively. Most seropositive hinds to both protozoans showed a stable antibody titer pattern from mating to the end of gestation, and a lower proportion developed an increase in titers suggesting infection recrudescence. Seroconversion during the gestational period was demonstrated in 6 and 50 hinds for N. caninum and T. gondii, respectively. Hinds with fetal mortality were more likely to be seropositive to N. caninum (OR = 3.1) or have N. caninum titers ≥400 (OR = 27.4) than hinds that weaned a fawn. No statistical associations were detected for T. gondii seropositivity and reproductive losses. The pregnancy rate was not affected by N. caninum or T. gondii infection, while the serological evidence of N. caninum causing postnatal mortality was marginal. Based on serological evidence, N. caninum would be a potential abortigenic agent in red deer hinds.

Exogenous Melatonin Improves the Reproductive Outcomes of Yearling Iberian Red Deer (Cervus elaphus hispanicus) Hinds.

Simple SummaryIncreasing the reproductive performance of hinds is considered to be a key factor of overall farm deer productivity. In the case of yearling hinds, this aspect becomes more important, as a delay in the pubertal onset will compromise the reproductive performance of the entire herd (decreased fertility), and these yearling hinds will carry this ‘late’ condition throughout their reproductive life. The aim of this study was to explore the use of melatonin implants on yearling Iberian red deer (Cervus elaphus hispanicus) hinds to improve their fertility outcomes, advance the calving date and the calves’ weight, and to prevent the negative impact of yearling hinds’ low liveweight on their reproductive outcomes. Melatonin implants (18 mg), administered three-fold (two implants each time) every 30 days before the breeding season, rendered significantly higher fertility rates (regardless of the yearling hind’s weight) and heavier calves, and advanced the calving date in the yearling hinds by 15 days compared to non-treated hinds. In addition, halving the number of yearling hinds that received melatonin provided a similar benefit to a large-scale treatment of the whole herd, which indicates female-to-female stimulation of the ovarian activity. Taken together, this protocol for melatonin treatment simplifies its administration, reduces its costs, and assures the enhancement of the reproductive productivity of the entire farm.The aim of this study was to assess the effect of melatonin implants on the reproductive performance of yearling Iberian red deer (Cervus elaphus hispanicus) hinds. It also explored exogenous melatonin administration as a tool to minimize the negative effect of a low yearling hind’s liveweight on their reproductive efficiency. In addition, the effect of melatonin-treated yearling hinds on non-treated hinds was studied in order to provide a practical and economical protocol to improve farms’ productivity. A total of 4520 Iberian red deer hinds belonging to the same farm were included in this study. Melatonin (108 mg/hind) implants were administered three-fold every 30 days before the breeding season. Fertility rates, calves’ weights and calving dates were registered for each hind. The results showed that exogenous melatonin increased significantly (p < 0.05) the calves’ weight (32.39 ± 1.07 kg vs. 27.65 ± 1.11 kg for Weight 1calf (July) and 46.59 ± 1.50 kg vs. 41.79 ± 1.54 kg for Weight 2calf (August, at weaning)) and advanced the calving date by 15 days in yearling hinds compared to the non-treated group. In addition, the administration of melatonin implants before the breeding season was able to minimize the negative effect of low yearling hinds’ liveweight (Weight 1hind) on their future reproductive outcomes, as the fertility rates increased by 46% and the calves’ weight increased by 7 kg after the melatonin treatment, regardless of the yearlings’ weight. Finally, when both experimental groups (melatonin and non-treated) were kept separate, higher fertility rates (76.73 ± 7.18% vs. 66.94 ± 7.41%) were observed for the melatonin-treated hinds compared to the non-treated hinds. However, when both groups of yearling hinds were maintained together, no significant differences were observed in their fertility outcomes (78.13 ± 21.26% vs. 78.12 ± 23.32%). Therefore, melatonin implants may be used in yearling Iberian red deer hinds as a management tool to improve their reproductive productivity.

Clone-dependent browsing damage of poplar plantations and the repellent potential of Populus nigra × P. maximowiczii ʻMax-4’

Browsing of poplar clones by wild ungulates is a widespread problem in short rotation coppice (SRC) plantations in Central Europe. We investigated the influence of poplar genotype on ungulate browsing intensity, identified the most browsing-resistant poplar clone and explored its repellent potential. Inspection of 11 poplar clones at 7 unfenced SRC plantations in the Czech Republic revealed the most avoided poplar clone by wildlife was Populus nigra × P. maximowiczii ʻMax-4’. Namely P. maximowiczii contributed to the repellent effect of ʻMax-4’ according to the analysis of impacts of individual parental poplar species on the browsing intensity of their hybrid progeny. In contrast, P. deltoides increased attractiveness of its hybrid progeny for browsing ungulates. Poplar browsing and bark stripping/fraying were not correlated. A subsequent feeding experiment with twigs of two poplar clones that had shown contrasting attractiveness for browsing in the field (intensively browsed P. × euroamericana AF24’ vs. avoided P. nigra × P. maximowiczii ʻMax-4’) demonstrated that red deer hinds (Cervus elaphus L.) bred on an experimental farm preferred ʻAF24’ over ʻMax-4’. There was no difference between consumption of fresh and wilted twigs of ʻMax-4’ suggesting the repellent compounds are stable over time. To uncover the chemical nature of repellent compounds, red deer hinds at the farm were offered grain fodder supplemented with polar and non-polar extracts of ʻMax-4’ shoots, commercial repellent (Stop Z) or empty carrier (controls). Non-polar extract of ʻMax-4’ produced transient feeding avoidance suggesting its potential as a game repellent, though optimisation of the extraction procedure and dosage is necessary.

No effect of inoculation site and injection device on the skin test response of red deer to the intradermal injection of Mycobacterium avium-derived purified protein derivative (PPD)

Mycobacterial diseases are important health issues in farmed deer. The single intradermal tuberculin test is the standard test for tuberculosis testing in deer. We studied two factors which might influence the response of deer to skin testing: the inoculation site and the injection device. Deer included in this study were 2.5 years old farmed red deer (Cervus elaphus) hinds (n = 80). Two areas of 3 cm × 3 cm were shaved at the left side of the neck. Site A (SA) was situated about 10 cm caudal to the head, while site B (SB) was 10 cm caudal to SA. All hinds received at the same time two 0.1 ml inoculations of Mycobacterium avium derived purified protein derivative (aPPD). One inoculation was made by syringe and the other one with the needle-free syringe Dermojet. To test the inoculation site effect, half of the animals were inoculated by Dermojet in SA and by syringe in SB to compare with the inoculation in SA by syringe and Dermojet in SB in the other half. No differences were recorded for the injection device nor for the inoculation site. Ten hinds had a skinfold increase larger than 30 tenths of mm by any injection device and inoculation site. Seven (9%) and 6 (8%) hinds were classified as positive by syringe and Dermojet, and at the anterior or posterior inoculation site, respectively. The distribution of skinfold thickness increases did not differ by injection device. Our findings support the needle-free Dermojet syringe as a suitable tool for skin-testing in red deer and suggest no relevant effect of the position of the inoculation site along the neck in red deer.

Progesterone and Cortisol Levels in Blood and Hair of Wild Pregnant Red Deer (Cervus Elaphus) Hinds.

Simple SummaryThe red deer, also known as the royal deer or European deer, is an artiodactyl mammal belonging to the Cervidae family, widely diffused in almost all of continental Europe. At the beginning of autumn in the Northern Hemisphere, the mating season begins. The males of red deer, called stags, are synchronized with the females, called hinds; indeed, at the beginning of the mating season, they show a marked increase in testosterone to match the hinds’ estrus cycle. Gestation lasts about 230 days, so that calves are born in mid to late spring, the most favorable period for their survival. Scientific data on the reproduction physiology of this peculiar species in wild conditions are lacking, including hormonal variations during pregnancy. The present study describes mean levels of two critical hormones, cortisol and progesterone, in both blood and hair of wild pregnant red deer hinds. Correlation analysis confirmed how animals hunted in later phases of pregnancy have higher hair progesterone.The red deer (Cervus elaphus L., 1758) is one of the largest deer species in the world. Females are seasonal polyestrous, with negative photoperiod: the increase of the night peak of melatonin determines the secretion of GnRH and, therefore, LH and FSH. To date there is little information regarding the hormonal control during pregnancy for this species; this could be due to the difficulty of sampling wild subjects, while farmed animals’ hormonal concentrations may not reflect the physiology of the animal in a natural state. In this study we evaluated the concentration of cortisol and progesterone, extracted from blood and hair, on 10 wild and pregnant red deer females. Belonging to the population of the Bolognese Apennines (Italy), the hinds were sampled in the January–March 2018 period, according to the regional selective hunting plan. Plasma progesterone (P4) ranged from a minimum of 1.9 to a maximum of 7.48 ng/mL; while hair P4 concentrations varied from 41.68 to 153.57 pg/mg. The plasma and hair cortisol ranges are respectively 0.4–2.97 ng/mL and 0.03–0.55 pg/mg; the only significant correlation was found between hair concentration of P4 and the date of death. The results of this preliminary study represent a small step towards a better knowledge of this species’ physiology during pregnancy.

Parenteral Cu Supplementation of Late-Gestating and Lactating Iberian Red Deer Hinds Fed a Balanced Diet Reduces Somatic Cell Count and Modifies Mineral Profile of Milk

Simple SummaryThe benefits of Cu supplementation have been reported for male deer and cows. In deer, supplementation with this mineral is frequent in males even in animals receiving balanced diets. The benefits of Cu supplementation for antler cortical thickness in adult deer and for deer meat characteristics have also been demonstrated. Since Cu supplementation of cows has positive effects to achieve optimal offspring growth, it could be interesting to assess such effects for hinds since this mineral is transported across the placenta and has an important role in animal growth. Our results in lactating hinds showed that Cu supplementation decreased the number of somatic cells, improving the health quality of the milk and indicating a lower risk of mastitis. It also increased Ca and K content of milk, although not that of Cu. This is the first study demonstrating that Cu supplementation during late-gestation and lactation in hinds fed a balanced diet could be a good strategy to reduce somatic cell count (improving the health quality of milk) and modify the mineral profile of milk increasing its Ca content.This study describes the effects that Cu supplementation of late-gestating and lactating females (hinds) of Iberian red deer fed a balanced diet have on milk production, composition, and somatic cell count (SCC). Experimental hinds (n = 9) were subcutaneously injected every 42 days with Cu (0.83 mg Cu/kg body weight) from day 202 of gestation until the end of lactation (week 18). Control hinds (n = 8) were injected with a physiological saline solution with the same volume and at the same frequency as the experimental group. Copper supplementation decreased the SCC from 1.64 to 1.36 log 10/mL (p = 0.003) and modified the milk mineral profile. In particular, milk from hinds supplemented with Cu had more Ca (p = 0.02), Mg (p = 0.06), and K (p = 0.03) than milk from control hinds. However, Cu supplementation did not influence the Cu content of milk. Therefore, it can be concluded that Cu supplementation of hinds fed a balanced diet from late-gestation to the end of lactation could be a good strategy to reduce SCC and modify the mineral profile of milk increasing its Ca content.

Body composition and venison quality of farmed red deer (Cervus elaphus) hinds reared on grass, papilionaceous or mixed pasture paddocks.

Red deer (Cervus elaphus) hinds () of identical initial body weight (BW, ca. 68 kg) were reared on a monocotyledonous grass (G group), on a grass–papilionaceous (GP group) or on pure papilionaceous pasture each of 2 ha (P group) for 219 d. At the end of the experiment carcass tissue composition was assessed by means of computer tomography, slaughter value and meat quality were characterized and tissue – longissimus thoracis et lumborum (LTL), thigh and liver – samples were taken for fatty acid composition analysis. The primary aim was to assess nutrition-driven differences.Hinds of group P provided higher final BW (101 kg vs. 90 and 91.9 kg in groups G and GP, respectively) and higher BW gain (32.6 kg during the total period vs. 22.4 and 22.1 kg). The carcass weight exceeded those of the other groups significantly (68.8 kg vs. 59.3 and 63.2 kg), while there was no difference among groups in the perirenal fat weight and red color tone () of the LTL. Groups G and P differed significantly in the LTL weight (highest in P), its dripping loss (lowest in G), lightness (L; highest in P) and yellow color tone ().In the thigh muscle, LTL and liver the highest proportion of fatty acid CLA9c11t was reached on the G pasture, and the same trend was true for docosahexaenoic acid (DHA , C22:6 n3) in the muscles. The n6 n3 fatty acid ratio was the highest on the P pasture in the liver and both muscles. The liver incorporated the highest proportion of linoleic acid (C18:2 n6) and converted it rather effectively to arachidonic acid (C20:4 n6), coupled with the lowest -linolenic acid presence.In conclusion, concerning muscle mass production, group P proved to be the most advantageous pasture; meanwhile LTL meat quality factors (dripping loss, DHA proportion, pH, color) were more favorable on the G pasture.

Gestation length in red deer: genetically determined or environmentally controlled?

The red deer (Cervus elaphus) of European origin (e.g. subspecies scoticus, hispanicus, hippelaphus) is a medium sized (100-150kg mature hind weight) ruminant that exhibits highly seasonally patterns of autumn conceptions and summer births. Historic data indicate average (+/- s.d.) gestation length of 233-234 (+/- 2-4) days. Recently, however, there has been growing awareness that there is considerably greater variation in gestation length than earlier indicated and that there is a significant element of environmental, and possibly even social, control over the duration of pregnancy in this species. Imposition of variable levels of nutrition over late pregnancy of red deer hinds has been observed to influence fetal growth trajectory and gestation length, with no apparent effect on birth weight. This supports a hypothesis that under conditions of modest feed imbalance, variation in gestation length compensates for variation in fetal growth trajectory to ensure optimisation of birth weight. More recent studies on primiparous (24 month old) red deer hinds have identified surprisingly large variation in gestation length (193-263 days) compared with adult hinds (228-243 days), with earlier conceiving individuals within the primiparous cohort expressing significantly longer gestation than the later conceiving hinds, resulting in a higher level of calving synchrony than expected from known conception dates. This introduces an intriguing hypothesis of social indicative effects on parturition timing to promote within-cohort birth synchrony. Collectively, these data debunk the commonly held notion that gestation length of red deer is genetically fixed within strict limits. A review of the literature points to this as possibly a common phenomenon across a range of non-domesticated ruminant species but this conclusion is not supported by numerous conflicting studies on domestic sheep and cattle.

Impact of capture and chemical immobilization on the spatial behaviour of red deer Cervus elaphus hinds

Research and management programs of wild animal populations often require intensive field actions, which make direct interventions on animals such as capture, immobilization and manipulation, frequently necessary. Such events, however, could induce a stress response causing physiological and behavioural alterations in the individuals. Knowing the impact of these practices in the post-release phase is of crucial importance when studying the spatial behaviour of wild species. Our study aimed to investigate the potential effect of narcosis and application of GPS collars on 17 red deer Cervus elaphus hinds living in a mountainous area in northern Apennine, Italy. We conducted the analysis at a temporal scale of 45 days after release, in order to assess the response of animals in terms of changes in movement rates, distance from the barycentre of their positions and distance from the capture sites. We then compared habitat selection between the period of disturbance and the following days. This work represents the first study of the behavioural responses of wild red deer to capture and handling procedures. We showed that these operations significantly affect the spatial behaviour of hinds by inducing a short-term increase in movement rates and by keeping the animals away from the centre of their activity, for a period no longer than 10 days. The habitat selection analysis remarked a tendency to escape from human disturbance, by avoiding hunting sites and anthropized locations in favour of forest cover. Red deer hinds thus, seem to cope with stressful events and disturbance by adopting a flight behaviour, which includes moving away from the capture area and seeking refuges. The differences highlighted between the ‘stressful’ period and the following one, showed that such modifications persist for a limited time frame and suggested that this capture method is unlikely to lead to permanent alterations of behaviour.

Different maternal investment strategies for male and female calves in a polygynous mammal.

Maternal effects occur when the phenotype of the mother influences that of the young to the detriment of her survival, growth or fitness. The investment of the mother can be affected by maternal body condition and/or experience. Trivers–Willard Hypothesis (TWH) and Local Resource Competition Hypothesis (LRCH) are the main hypotheses used to explain bias in birth sex-ratios in mammals, as well as for sex-biased maternal investment. Both hypotheses suggest that a different amount of investment must be expected according to the sex of the young. However, recent studies suggest that these differences are not in quantity but in the strategies: mechanisms and objectives may differ for each sex. We studied how maternal characteristics (age, body mass, body condition, and dominance status) influence relevant aspects of the birth and early growth of the calf (birth date, birth body mass, body mass at weaning, and body condition at weaning) separately for each sex; and how that investment is mediated by milk production and composition (lactose, fat, and protein). One hundred eighty-eight newborns from 75 captive red deer hinds aged from 2 to 19 years were analyzed. The main differential investment observed was related to birth date: when producing a female, hinds give birth earlier in the season only if they have a good body condition; however, when gestating a male it is the older hinds those which deliver earlier. Subsequently, milk production and composition are correlated with birth body mass in female calves, but to weaning body mass in males. Thus, only hind body mass affects the weaning body mass of female calves, compared with age and hind body mass in males. These results suggest that while TWH fits the maternal investment strategy found for male calves, it is LRCH which correlates with the maternal investment patterns observed for females.

Social rank affects the haematologic profile in red deer hinds

We studied the effects of social rank on the haematologic profile in a herd of 24 female Iberian red deer hinds. Social rank hierarchy was determined and blood samples were...

Old and young female voices: effects of body weight, condition and social discomfort on the vocal aging in red deer hinds (Cervus elaphus)

Abstract In female terrestrial mammals, vocal aging has only been studied in humans and pandas. In cervids displaying convergent sex dimorphism of vocal apparatus with humans, vocal aging is only investigated in males. This cross-sectional study examined acoustic variables of nasal (closed-mouth) and oral (open-mouth) contact calls of 32 farmed Iberian red deer hinds (Cervus elaphus hispanicus) aged of 4-18 years and their relationships with caller´s age, weight, social discomfort score (bites of other hinds on hind pelt) and body condition score (fat reserves). Decrease of fundamental frequency was associated with age in both oral and nasal calls, but more prominently in the nasal calls. An increase in call duration, peak frequency and power quartiles was associated with a higher degree of bites due to social aggression. Weight and body condition weakly influenced acoustic traits. We discuss that vocal aging of hinds parallels that of vocal aging in human females.

Social rank and reproductive performance in a herd of farmed red deer females (Cervus elaphus)

Hierarchical relationships between individuals determine unequal access to recourses like food and individuals of the other gender, resulting in a higher reproductive success of high-social ranked individuals. Environmental conditions and food availability may determine how strong these effects are. The aim of this work was to determine if social rank of farmed red deer females affect the reproductive results of a hormonal oestrous synchronisation treatment with ad libitum food. The studied responses included the time to oestrus onset, percentage of females that came into oestrus, conception and calving rates, gestation length, and calf gender. The study was performed during autumn on a research farm located in Mexico (20°36ʹ N, 99°55ʹ W). Forty-nine adult red deer females were assigned to two replications of 21 and 28 animals respectively and were allocated into independent paddocks with ad libitum food and water availability. Oestrous cycles were synchronised with a traditional protocol of intravaginal devices impregnated with progesterone. Agonistic behaviours between females were recorded (total = 1626 interactions), hierarchical position (Success Index = SI) of each animal was calculated and individuals were categorised as high (n = 13), medium (n = 20) or low-ranked (n = 16) individuals. Reproductive data were recorded during the 5 days after the oestrous synchronisation treatment and during the calving period. Any of the recorded responses differ between HR, MR and LR females. Female SI, age and bodyweight were not related with the probability of coming into oestrus, result pregnant, and giving birth to a male calf. Thirty-seven (78.5%) females of this study gave birth. From these calves, 15 were males and 22 were females. Due to high percentage of females in oestrus that gave birth (85.7%), it was not possible to detect the relationship between female SI, age, and bodyweight with the conception rate. Female SI, age and bodyweight were unrelated to time to oestrus onset (r2 = 0.09; P = 0.17), and to gestation length (r2 = 0.10; P = 0.20). In conclusion, with ad libitum high quality food, the social rank of red deer hinds did not affect the time to oestrus onset, percentage of females that came into oestrus, gestation length, calving and conception rates, and offspring sex ratio after an oestrous synchronisation hormonal treatment.

Effects of repeated comparative intradermal tuberculin testing on test results: a longitudinal study in TB-free red deer.

BackgroundDiagnosing tuberculosis (TB) in farmed red deer (Cervus elaphus) is challenging and might require combining cellular and humoral diagnostic tests. Repeated skin-testing with mycobacterial purified protein derivatives (PPDs) might sensitize or desensitize the subjects to both kinds of diagnostic tools. We evaluated the effect of repeated (every 6 months) comparative tuberculin skin testing on skin test and ELISA responsiveness in farmed red deer hinds from a TB-free herd. Eighteen 8-month old hinds were inoculated with bovine and avian PPDs and the mitogen phytohaemagglutinin (PHA), as positive control and concurrently tested by ELISA for antibodies against avian (avian PPD, aPPD and protoplasmatic antigen 3, PPA3) and bovine antigens (bPPD and MPB70). Blood serum was also sampled three weeks after each skin testing round and tested for antibodies against aPPD and bPPD, in order to detect eventual antibody level boosts. Testing took place every six months from winter 2012 until winter 2015.ResultsThe skin test response to both PPDs peaked during the second and third test round, returning to standard values thereafter. Individual variability was particularly high at the first year and early second year testing rounds (first intradermal test and blood sampling; first winter). The antibody response to avian antigens increased through time, while no such increase was recorded for bovine antigens. The antibody boost three weeks after skin testing was more marked for avian PPD. However, there was no consistent trend in the boosting response through time.ConclusionRepeated comparative skin testing at six month intervals did not cause progressive increments in skin test responsiveness or antibody production. Specifically, we observed no loss of the skin test response to bPPD and also no progressive loss of the boosting effect in the ELISA responses. However, we recorded increases through time in the antibody levels against avian mycobacterial antigens, possibly due to the progressive exposure to MAP or to other cross-reacting environmental mycobacteria. These findings should be taken into account in designing and interpreting TB testing schemes in farmed deer.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-016-0825-2) contains supplementary material, which is available to authorized users.

Examining the impacts of red deer hind body condition score and pasture forage mass on calf weaning weight

The effect of pre-calving hind body condition and the interaction with pasture forage mass during lactation on calf growth and intake to weaning were investigated. Two-hundred and forty red deer hinds (Cervus elaphus scoticus × hippelaphus) of average body condition score (BCS) 3.5 were subjected to either ad libitum or restricted feeding for the 4 weeks before the expected start of calving (31 October) to create hinds of low (2.5) or high (3.5) BCS. The hinds were then grazed continuously on pasture of either low (&lt;1200 kg DM/ha) or high (&gt;2400 kg DM/ha) forage mass during lactation (29 October–25 March). In a 2 × 2 crossover design liveweight, liveweight gain and pasture intake were measured in both hinds and calves. Low hind body condition score (BCS 2.5) at the onset of lactation resulted in low calf weaning weight (46.9 kg) when forage mass was low, but not when forage mass was high (57.3 kg). High BCS (3.5) in hinds resulted in intermediate calf weaning weight when on low forage mass (51.2 kg) and high calf weaning weight when forage mass was high (56.6 kg). Both BCS and forage mass influenced calculated total milk production.

Oral administration of heat-inactivated Mycobacterium bovis reduces the response of farmed red deer to avian and bovine tuberculin

Orally delivered mycobacterial antigens may not sensitize the immunized animals causing a positive tuberculin skin test response. As the first step to address this critical issue, we characterized the response of farmed red deer (Cervus elaphus) to orally delivered heat-inactivated Mycobacterium bovis. Thirty-two adult red deer hinds from a farm known to be free of tuberculosis (TB) were randomly assigned to two different treatment groups, immunized (n=24) and control (n=8). Immunized hinds were dosed orally with 2ml of PBS containing 6×106 heat-inactivated M. bovis. The mean skin test response of immunized deer to both avian purified protein derivative (aPPD) and bovine PPD (bPPD) was consistently lower in immunized than in control hinds. One year after immunization, immunized hinds had a significant reduction in the skin test response to aPPD and in the ELISA antibody levels against both aPPD and bPPD (24–36% reduction; P<0.05). By contrast, no significant change was observed in the skin test response to phytohaemagglutinin, or in the ELISA antibody levels against the M. bovis specific antigen MPB70. The mRNA levels for C3, IFN-γ and IL-1β and serum protein levels for IFN-γ and IL-1β did not vary between immunized and control deer. However, serum C3 protein levels were significantly higher (P=0.001) in immunized than in control deer six months after immunization. These results confirm that oral heat-inactivated M. bovis does not sensitize farmed red deer and therefore does not cause false-positive responses in the tuberculin skin test. The absence of sensitization in orally immunized deer opens the possibility of testing the vaccine in deer and possibly other ruminants without the risk of causing false-positive reactions in TB-tests. This study also provided the first evidence that orally-delivered inactivated mycobacterial antigens elicit some kind of immune response in a ruminant.

Hind genotype influences on lactation and calf growth in farmed red deer (Cervus elaphus)

Multiparous red deer (Cervus elaphus scoticus) hinds (n=18) were artificially inseminated with semen from a red deer stag (n=8) or wapiti bull (C.e. nelsoni) (n=10) to produce red deer or F1 crossbred (C.e. scoticus×C.e. nelsoni) calves. A further seven wapiti×red deer (F1) hinds were artificially inseminated with semen from an unrelated F1 stag to test the hypotheses that (1) crossbred hinds rearing crossbred calves will produce more milk to support calf growth than red deer hinds rearing crossbred calves, and (2) the extra lactation demand of crossbred calves will exert a more detrimental effect on red deer hind live weight and body condition than would occur if the dam was a crossbred hind. Hinds and calves were grazed on ryegrass and white clover pastures and supplemented with pasture silage and barley grain when pasture supply was inadequate. Calves were left with their mothers until approximately 240 days of age. Mean body condition score (BCS) was lower in F1 hinds rearing F2 calves during late lactation (days 150 to 240, P<0.05) than red deer hinds rearing either red deer or F1 calves. F1 calves grew significantly faster than red deer calves and were heavier at all ages, while F2 calves were intermediate. Milk intake of both F1 and F2 calves was higher than red deer calves until day 76 of lactation (P>0.05), but similar thereafter. Male calves had a higher milk intake than female calves at 20 days of age only (P=0.004). The average hind pasture intake was greatest in F1 hinds rearing F2 calves, intermediate in red deer hinds rearing F1 calves and lowest in red deer hinds rearing red deer calves (P=0.038). Total milk output for the lactation increased by approximately 14.6kg/kg average calf live weight at weaning for both F1 hinds rearing F2 calves (P=0.008) and red deer hinds rearing red deer calves (P=0.072), suggesting that calf demand rather than hind liveweight was the key determinant of lactation performance. This was not the case for red deer hinds rearing F1 calves suggesting that there is an upper limit to lactation output depending on hind size. These results do not support the hypothesis that a crossbred hind rearing a crossbred calf will produce more milk than a red deer hind rearing a crossbred calf and provides evidence that the milk production of the hind is primarily driven by milk demand of the calf but has an upper limit depending on the size of the hind. The second hypothesis was not supported as F1 hinds rearing F2 calves exhibited greater loss of body condition score relative to the red deer hinds rearing either red deer or F1 calves in this study. This suggests that the additional energetic demands on a hind from feeding an F1 calf may be met with adequate nutrition.

Do red deer hinds prefer stags that produce harsh roars in mate choice contexts?

Red deer stags give two types of roars during the breeding season, termed ‘common’ and ‘harsh’ roars. This study tested the hypothesis that the characteristic spectro-temporal structure of male harsh roars functions to directly attract females towards male callers during the breeding season. The results show that oestrous hinds look for longer towards speakers broadcasting sequences containing harsh roars, but do not preferentially approach or spend more time in close proximity to speakers broadcasting harsh roars over those broadcasting only common roars. While these observations confirm that the specific acoustic structure of male harsh roars functions to draw the attention of hinds, they are not consistent with the notion that these calls have an immediate impact on mate choice decisions by stimulating oestrous hinds to move towards male callers. Consequently, we suggest that intersexual selection through female mate choice is unlikely to be a major factor driving the evolution of male red deer harsh roars.