Accuracy of pregnancy diagnosis and prediction of calving date in red deer using real-time ultrasound scanning

One hundred and sixty-two 18-month-old farmed red deer were used to test the accuracy of pregnancy detection and equations for predicting gestational age. Deer ranging from 30 to 110 days gestation were examined by rectal ultrasonography using a 5 MHz transducer while they were standing. Each scan was recorded on video tape for measurements of uterine diameter, amniotic sac diameters, crown-rump length, head length, head diameter, nose length, chest depth, chest width and placentome base-apex length and width. Fetal age was calculated from the mean of the age predictions derived from each dimension measured on individual deer, for 132 deer between 44 and 110 days gestation. All the hinds diagnosed as pregnant produced offspring, and all the hinds diagnosed as not pregnant failed to produce offspring. Between one and six fetal and uterine dimensions were measurable and the number measurable increased with fetal age. The mean error of calving date prediction in 132 deer was 0.97 days. The error of prediction when measurements were made between 44 and 60 days was 0.44 days, whereas between 61 and 80 days and between 81 and 110 days the errors were +0.95 and +4.72 days, respectively. The estimates of calving date were all within 13 days of the calving date.     

Ultrasonography of the reproductive tract and early pregnancy in red deer

Thirty-five farmed red deer hinds two years of age or older were observed during mating in April and May and the dates of oestrus and, or, matings were recorded. From immediately before the breeding season and at approximately weekly intervals from the start of mating until all deer were 42 days pregnant, rectal ultrasonographic scans were taken using a 5 MHz linear transducer while deer were held standing in a restraining device. Scans were recorded on video. The vagina and cervix were visible with the lumen appearing as a continuous or intermittent white line, respectively. The non-pregnant uterus was observed in most cases and was immediately anterior to the bladder. Structures resembling ovaries were seen only occasionally. By seven days gestation a 5 mm vesicle could be observed in a few deer, and by day 14, oedema of uterine horns was apparent in some cases. A comma-shaped fetal mass 6 mm long, fetal membranes and placentomes could be observed on day 24. The heart beat was observed on day 28 when the fetus was 10 mm long. Limb buds were observed on day 31 and by day 37 the head with nose and eyes was distinguishable. Fetal movements were first observed on day 42. The accuracy of pregnancy detection before day 20 was 35 per cent, between 21 and 30 days gestation 71 per cent and from 31 to 42 days 98 per cent.     

Effects of vaginal Brucella ovis infection of red deer hinds on reproductive performance, and venereal transmission to stags

AIMS: To investigate the effects of vaginal Brucella ovis infection on the reproductive performance of red deer (Cervus elaphus) hinds. To determine whether stags may become infected with B. ovis by venereal transmission from mating infected hinds. METHODS: Thirty mixed-age red deer hinds serologically negative for B. ovis antibodies were synchronised for oestrus on 22 March 2000. B. ovis was inoculated into the vagina of each hind at oestrus and again, 18 days later. At oestrus, hinds were randomly allocated to six groups, each joined with a 16 month-old red deer stag seronegative for B. ovis, for 55 days. Hinds were blood sampled and scanned for pregnancy using rectal ultrasonography at monthly intervals. Six pregnant and four non-pregnant hinds were slaughtered pre-calving and three hinds were slaughtered post-calving. Reproductive tracts and foetuses were examined grossly, histologically and microbiologically. Calves were identified and blood sampled within 3 days of birth. Hinds and calves were blood sampled in February and May 2001 and vaginal swabs were collected from hinds for B. ovis culture. Blood was collected from stags, 5 and 19 days after mating and semen was collected for B. ovis culture. The 17 remaining hinds were mated in 2001 to two mixed-age wapiti (Cervus canadensis) stags. Both stags were blood sampled after mating. Sera were tested in a B. ovis complement fixation test (CFT) and enzyme-linked immunosorbent assay (ELISA). RESULTS: All 30 hinds developed B. ovis antibody levels, measurable using either the CFT or ELISA, but these did not remain elevated. There was no evidence of infection, either by gross pathology, histopathology or microbiological culture in the ten hinds or six foetuses slaughtered pre-calving. All remaining 20 hinds produced normal calves, 15 of which survived until weaning. Three hinds experienced dystocia and gave birth to dead calves and two calves died within 4 days of birth. One hind which had dystocia was euthanased. Samples from this hind and from 3/5 dead calves showed no evidence of B. ovis infection. B. ovis was cultured from the vagina of 1/19 hinds 48 weeks after inoculation, at which time B. ovis CFT and ELISA results for this hind were negative. Most calves had B. ovis serum antibodies at 1-3 days of age but levels were negligible when sampled at 10-15 weeks of age. Foetuses and dead calves were all seronegative. Three of the five red deer stags used for mating became infected with B. ovis. The two wapiti stags used to mate the remaining 17 hinds the following year remained seronegative. CONCLUSIONS: B. ovis is unlikely to have significant detrimental effects on the reproductive performance of red deer hinds. Venereal transmission via the vagina of hinds is a possible route of transmission between stags. It is possible that survival of the organism in the vagina of some hinds could create difficulties in disease control programmes. CLINICAL RELEVANCE: B. ovis infection of hinds at the time of mating is unlikely to cause significant reproductive losses. Venereal transmission of B. ovis between stags via the hinds may occur when groups of hinds are joined with more than one stag.     

Disease and mortality on red deer farms in New Zealand

A longitudinal observational study of 15 red deer farms was carried out in New Zealand for two years from March 1992. The deer were monitored for performance and health problems, and farm management practices were recorded. Numbers at risk were 4,683 hind-years, 2,459 stag-years and 3,202 weaner-years. The numbers of primiparous and adult hinds at risk of losing their progeny by weaning were 653 and 3,364, respectively. Where possible, postmortem examinations were carried out, and organs were sampled for histological and microbiological investigation. Rates of mortality varied with season with most stag and hind deaths in winter and weaner deaths in autumn and winter. Overall mortality rates were 1.77, 2.60 and 5.87 per 100 deer-years for hinds, stags and weaners, respectively. Malignant catarrhal fever accounted for 0.53 stag and 0.17 hind deaths per 100 deer-years at risk Misadventure, including broken bones, accounted for 15.4 per cent of weaner mortalities, or 0.53 weaner mortalities per 100 weaner-three months in autumn. Yersiniosis was confirmed in 18.6 per cent of weaner deaths, or 1.09 weaners per 100 weaner-years during the first six months after weaning, but was also suspected but unconfirmed in a further 41 per cent of weaner mortalities. Overall, 17 per cent of yearling hinds, and 9.2 per cent of adult hinds lost their progeny between pregnancy diagnosis in June and weaning in March. One outbreak of osteochondrosis was recorded. Mortality rates varied between farms and many mortalities were preventable.     

Field evaluation of melatonin implants to advance the breeding season in 1-year-old farmed red deer hinds

The efficacy of controlled-release melatonin implants to advance the onset of the breeding season was assessed in 1-year-old red deer hinds on five commercial deer farms in various localities in the North Island of New Zealand. Between 44 and 60 hinds in each of six herds were equally divided among treatment and control groups at each site. Melatonin treatment commenced between 27 November and 16 December and was achieved by the subcutaneous administration of two 18 mg melatonin implants. Three doses were given at about 30 day intervals. Two adult stags for each hind group were treated with three 18 mg melatonin implants concurrently on either two or three occasions. On each property, treated and control hinds were joined as one herd to treated stags commencing 30 January-10 February and concluding 15 May-2 June. The hinds in the four experimental herds underwent rectal ultrasound examination May-June to estimate conception rate and foetal age. Calving dates, hind and calf mortalities, weaning weights, and the antler growth cycle and harvesting data were recorded. Overall, treatment with melatonin resulted in an average advance of the median calving date of 22 days (range 12-36 days) when compared with untreated controls in the same herds. Pregnancy rates were 91.3-100% in treated hinds and 63.6-100% in untreated hinds. There were no differences in calf mortality or calf sex ratio between treated and untreated groups. No hind deaths could be attributed to melatonin treatment. The weaning weights of calves were 5.68 kg and 4.43 kg heavier for the male and female offspring of treated hinds respectively, compared with those of control hinds. Treated stags commenced rutting behaviour earlier than normal and the antler casting and growth cycle was advanced. Treatment resulted in advancement of the seasonal pattern of coat changes in hinds and stags, but no untoward side effects of the melatonin treatments were observed.     

Reproductive performance of farmed red deer (Cervus elaphus) in New Zealand: II. Risk factors for adult hind conception.

A 2-year longitudinal observational study of 15 red deer farms was carried out in New Zealand from March 1992. About 2600 adult hinds were individually monitored for reproductive success. After mating, hinds were pregnancy-tested by ultrasound and were classified as having conceived before 1 May, after 1 May or as being not pregnant. Risk factors potentially affecting the probability of conception before 1 May or of conception that year were investigated using path analysis. Final path diagrams were used to formulate a putative management strategy for farmers to achieve the desired reproductive performance from adult hinds. To achieve a high pregnancy rate early in the mating season, farmers should wean calves early, exclude hinds which failed to rear a calf to weaning and hinds with a body condition score < or = 2.0 at mating, join hinds early with one or more sire stags, use only experienced sires for mating, limit the hind: stag ratio, use at least one back-up sire after the peak of mating, keep mating mobs away from disturbance and avoid shifting or handling mating mobs. The farmer should choose paddocks with high green pasture allowance and grazed down to no less than 5 cm high.     

Evaluation of fetal growth and estimation of fetal age based on skeletal growth in Hokkaido sika deer (Cervus nippon yesoensis Heude, 1884)

We investigated fetal development and the estimation of fetal age of 127 Hokkaido sika deer fetuses, categorizing them into three groups according to the nutritional condition of populations. The order and time of the appearance of ossification centers were clarified, and fetal age was determined based on bone length and the appearance of ossification centers. Then we observed the differences in fetal growth among three populations, and discussed the effect of poor nutrition on the fetal growth. The results suggest that fetal diaphysial length of the femur was affected very little by nutritional conditions, whereas conception dates were delayed and fetal weight was restricted as the nutritional condition became poorer. Although it is impossible to know the exact accurate fetal age in wild populations, it was possible to create a standard to estimate fetal age more precisely by the method described in this study. Both the bone length and the appearance of ossification centers are reliable indices to estimate fetal age precisely in measurements available from fetuses of unknown age, and can be applied to estimate the fetal age of other populations of sika deer, whereas estimation of fetal age based on weight is prone to great errors.     

Diagnosis of pregnancy and prediction of fetal age in red deer by real-time ultrasonic scanning

Sixteen pregnant red deer hinds were scanned using real-time ultra sound at regular intervals during the first 150 days of pregnancy. In the early stages of pregnancy, an intra-rectal linear array transducer was used but later in pregnancy the hinds were scanned externally with a sector scanner. Pregnancy was determined from 30 days of gestation by intra-rectal scanning, and from 50 days by external scanning. With advancing age the size of the fetus increased, and linear regressions of size on age gave residual standard deviations of 0.508 days for head diameter and 0.506 days for trunk diameter. It is concluded that this technique can be used to determine pregnancy with a high degree of accuracy from 30 days of gestation and to predict calving date from fetal measurements within the range 1.5 cm to 7 cm for head diameter or 0.5 cm to 8 cm for trunk diameter, corresponding to a fetal age range of 35 to 150 days.     

Changes in serum oestrone sulphate and progesterone levels of red deer hinds during pregnancy

Serum oestrone sulphate (E1S) and progesterone (P) levels were recorded from six red deer hinds throughout the first two-thirds of gestation. E1S was generally undetectable until 30 days post conception when levels rose, peaking between 60 and 80 days, and fell to lower values between 80 and 170 days post conception. P levels rose after conception and remained elevated for the remainder of the study. This study indicates that in general the presence of measurable E1S levels in serum of hinds is associated with pregnancy.     

Climate,female traits and population features as drivers of breeding timing in Mediterranean red deer populations

Understanding the factors that lead to variation in the timing of breeding in widespread species such as red deer (Cervus elaphus) is crucial to predict possible responses of wild populations to different climate scenarios. Here, we sought to further understand the causes of inter‐annual variation in the reproduction timing of female deer in Mediterranean environments. An integrative approach was used to identify the relative importance of individual, population and climate traits in the date of conception of free‐ranging deer, based on a dataset of 829 hinds culled during 12 years. We found that a population trait, density, was the most important factor explaining the variation in conception dates, with greater densities causing later conception dates. Body mass was the second in importance, with heavier females conceiving earlier than lighter ones. Almost equally important was the spring real bioclimatic index, a measure of plant productivity, causing later conception dates in the least productive springs (drier and hotter). Another climatic component, the end of summer drought, showed that the sooner the autumn arrives (greater rainfalls and cooler temperatures) the earlier the conception dates. Interestingly, age class was found to be a minor factor in determining conception date. Only older females (≥10 years old) conceived significantly later, suggesting reproductive senescence. This study highlights not only the importance of population and individual traits but also the influence of climatic parameters on the deer reproductive cycle in Mediterranean environments, giving valuable insight into how reproductive phenology may respond to seasonality and global climate changes.     

Estimation of the developmental age of the bovine fetus and newborn calf

Jersey cows from several herds provided 97 fetuses and 24 calves at fixed gestational intervals between 80 and 290 days after conception. The fetuses and calves were killed, weighed and measured and, after dissection, the sizes and weights of a range of skeletal and soft tissues were recorded. Six morphological measurements emerged as most suitable for the determination of developmental age in the normal fetus. By plotting their mean values and 95 per cent tolerance limits, the rates of growth and the variability of each measurement were defined. Long bone length was the most useful single measurement for predicting the developmental age of the fetus. Brain weight, bodyweight, crown-anus length and long bone length showed curvilinear growth patterns; age prediction equations derived from these measurements are complicated to use and additional simplified formulae have been derived. The number of appendicular ossification centres also had predictive value, but it could not be used to determine fetal developmental age between 100 and 160 days gestation.     

Risk factors for dystocia in farmed red deer (Cervus elaphus).

OBJECTIVE: To analyse data from a study of deer herd health and productivity to identify potential risk factors for the occurrence of dystocia. DESIGN: A 2-year longitudinal observational study of 14 red deer farms was carried out in New Zealand. About 2700 hinds were monitored each year for individual characteristics including body condition score (BCS), and reproductive performance. Grazing and calving management practices were recorded. During calving, farmers recorded calving difficulties (dystocia) that needed human assistance or caused the death of the hind. Risk factors potentially affecting the occurrence of dystocia were identified and analysed by multivariable statistical techniques. RESULTS: The percentage of hinds with dystocia was 0.52% (95% CI 0.32 to 0.78). Hinds with a post-winter BCS over 3.5 were 2.7 times as likely to experience dystocia as hinds scoring 3.5 or less. Given the same BCS class, bodyweight gain in late pregnancy was associated with an increased risk of dystocia. Grazing steep paddocks in the last trimester of pregnancy decreased the risk of dystocia in hinds with a BCS over 3.5. CONCLUSIONS: The risk of dystocia on red deer farms may be reduced if key individual animal, management and environmental factors are optimal.     

The testing season affects red deer skinfold increase in response to phytohaemagglutinin

Red deer (Cervus elaphus) have a pronounced seasonality in their physiology. The aim of this study was to assess the effect of the season on red deer responsiveness to skin testing with the phytohaemagglutinin (PHA) mitogen. Study subjects included 270 farmed adult red deer (19 stags and 251 hinds). The skin testing was carried out between January 2009 and August 2010. The animals were injected intradermally with a 0.1 ml volume containing 250 μg of PHA diluted in phosphate buffered saline. The skinfold thickness was measured immediately prior to injection and 72 h after administration, always by the same person and with three repeats per measurement. Single effects of sex and time on skin test responsiveness were significant (p < 0.001) as well as their interaction (p < 0.001). In winter (January), and considering the average of two years, the skinfold increase in response to the intradermal injection of 250 μg PHA was 2.1 times larger in stags and 1.4 times in hinds than in summer (August). While stags had 1.3 times larger responses than hinds in winter, the inverse occurred in summer, with 1.1 times larger responses in hinds. We also evidenced a limited inter-annual variation of skinfold increase in response to PHA in red deer. These findings have important consequences regarding the interpretation of skin test results in the ante-mortem diagnosis of tuberculosis and paratuberculosis, at least in deer.     

Reproductive performance of farmed red deer (Cervus elaphus) in New Zealand: III. Risk factors for yearling hind conception.

A 2-year longitudinal observational study of 15 red-deer farms was carried out in New Zealand from March 1992. Seven hundred yearling hinds were individually monitored for reproductive success. After mating, hinds were pregnancy tested by ultrasound and were classified as having conceived before 1 May, after 1 May, or as being not pregnant. Risk factors potentially affecting the probability of conception before 1 May or of conception that year were investigated using path analysis. To increase the probability of conceiving early, this study suggests yearling hinds should be selected prior to mating for high bodyweight and height. Young stags and hinds should be joined late summer (14 months of age) before mating. Mobs of yearling hinds should not be combined with large mobs of adult hinds. Paddocks with limited gullies, hills and trees should be chosen for mating. Finally, paddocks for mating should be away from human disturbance. To increase the probability of yearling hinds conceiving that year, yearling hinds should be in moderate-to-low body condition (around 2.5), and nutrition during mating should be prioritised to ensure optimal growth rates. Short and/or lightweight hinds may be mated successfully if they are well fed but they generally conceive later. Trees should be limited in the mating paddocks.     

Influence of calf genotype on dam lactation and calf growth in farmed red deer (Cervus elaphus)

Multiparous red deer (Cervus elaphus scoticus) hinds (n=17) were either mated to a red deer stag or artificially inseminated with semen from a wapiti bull (C.e. nelsoni) to produce red deer or F₁ crossbred (C.e. scoticus × C.e. nelsoni) calves to test the hypotheses that (1) red deer hinds rearing crossbred calves will produce significantly more milk to support calf growth than hinds rearing red deer calves, and (2) hind live weight and body condition may suffer as a result. 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 9–10 months of age when lactation had terminated naturally. Mean body condition score (BCS) loss was greater in hinds rearing F₁ calves than in hinds rearing red calves in the period from late gestation to mid-lactation (September–March, P<0.05). F₁ calves grew significantly faster than red deer calves and were heavier at all ages. From February onwards there was a consistent decline in milk intake, and by the latest measurement (22 July) milk production was negligible, and most hinds had ceased lactating. Milk intake by the F₁ calves was significantly greater until day 114, after which the measured milk intake was not significantly different. Pasture intake of the F₁ calves was significantly greater at day 114 but not at other times (P<0.05). The average hind pasture intake was also not significantly affected by calf genotype when adjusted for post calving hind live weight. The results support the hypothesis that a red deer hind rearing an F₁ calf produces significantly more milk than a hind rearing a red deer calf, suggesting that the growth of a red deer calf is limited by its milk demand rather than milk supply by the hind. The study also supported the second hypothesis. Hinds rearing F₁ calves exhibited greater losses of body condition score relative to the hinds rearing red deer calves, indicating that the hinds rearing F₁ calves were in a greater negative energy balance that hinds rearing red deer calves. This highlights the additional energetic demands on a hind from feeding an F₁ calf and in a farmed context the need to ensure that adequate nutrition is provided.     

Blood biochemical reference values for farmed red deer

The activities and concentrations of 30 whole blood and plasma constituents including enzymes, substrates, electrolytes and vitamins were determined in samples from 91 clinically healthy farmed red deer (Cervus elaphus) hinds ranging in age from one to 15 years. The hinds were randomly selected from a herd maintained on a mixture of reseeded and permanent hill pasture at an experimental research station in north east Scotland. The results were analysed statistically and the calculated means, standard errors and tolerance intervals provide a basis for diagnostic clinical chemistry in red deer. The data are compared with data from earlier reports on blood biochemistry in deer and other livestock species.     

Sarcoptic mange in red deer from Spain: improved surveillance or disease emergence?

Concern about emerging diseases has risen in recent years, and multihost situations have become increasingly relevant for wildlife management and conservation. We present data on Asturias, northern Spain, where 80 mangy red deer (Cervus elaphus) have been found since the beginning of the epizootic in chamois (Rupicapra pyrenaica parva) in 1993. We combine field and necropsy data with the results of a serosurvey using an in-house ELISA test to evaluate if deer mange due to Sarcoptes scabiei is an emerging disease in this area. The mean number of deer mange cases per year was 5, with a maximum of 16. No significant relationship was detected between monthly temperatures, rainfall or number of days with snow cover and the annual number of sarcoptic mange cases in red deer. Only 4 mangy red deer (5%) were detected outside the limits of scabietic chamois distribution during the same year, and all were less than 2500 m away from that limit. The longest distance reported between two consecutive mangy deer locations was 18 km. Mange cases were significantly more frequent in stags than in hinds and in adults than in juvenile deer. The time of the first mange detection in chamois in each sector, year with minimum number of chamois recorded, year with maximum chamois population decline rate and chamois density offered no significant correlation with red deer mange cases appearance moment and frequency. In the mange affected area, ELISA testing of 327 blood samples from hunter-harvested deer without obvious mange-compatible lesions revealed only 4 seropositive animals. All 83 sera from hunting preserves without clinical cases yielded negative ELISA results. According to these epidemiological data mange does not seem to threaten red deer populations in Asturias. However, continued monitoring of deer health and ELISA testing for sarcoptic mange is advisable.     

Survey of permanent wound tracts in the carcases of culled wild red deer in Scotland

The number and sites of permanent wound tracts in the carcases of 943 wild culled red deer (Cervus elaphus) were recorded. During the peak period of the red deer rut there was a significant increase in the number of these tracts in the carcases, which was associated with a decrease from 89 per cent to 71 per cent in the probability of the first permanent wound tract also being the last (the terminal probability). There were significantly more permanent wound tracts in the carcases of one group (predominantly males) than in a second group (predominantly females and calves). In carcases with a single tract in the trunk, in which the heart and lungs were also examined, 80 per cent had tracts involving the heart and/or lungs, the recommended thoracic target organs. Tracts involving vital structures in the neck were also common, with 15.3 per cent of the carcases with a single permanent tract having damage limited to cervical structures.     

Farm and slaughter survey of bovine tuberculosis in captive deer in Switzerland

In 1998, a survey was conducted by postal questionnaire to gather basic knowledge about the management, health and productivity of captive deer in Switzerland. In addition, lymph nodes were collected from slaughtered deer from 124 of the 262 holdings surveyed, and tested for Mycobacterium bovis and Mycobacterium tuberculosis. The total farmed deer population was 8389 animals kept on 485 holdings; 87 per cent were fallow deer, 8 per cent red deer, 4 per cent sika deer, and there were small numbers of other species. The median herd sizes were 12 for fallow deer and eight for red deer. Few owners had handling facilities or crushes. In none of the lymph nodes examined were lesions typical of bovine tuberculosis observed, and neither M bovis nor M tuberculosis was cultivated from any of the samples.     

Efficacy of human chorionic gonadotrophin and gonadotrophin releasing hormone for hastening ovulation in thoroughbred mares

Plasma progesterone levels were measured daily to determine the accuracy of diagnosing ovulation by rectal palpation carried out every other day; 81.5 per cent mares injected with human chorionic gonadotrophin showed increases of progesterone more than 1 ng/ml by 72 h after injection compared with 65 per cent of mares injected with gonadotrophin releasing hormone (GnRH) or saline. Mating at ovulation achieved a 74 per cent pregnancy rate in mares given hCG compared with 50 per cent given GnRH and 45 per cent controls. Diagnosis of ovulation per rectum on the basis of a pit in the ovarian surface or the presence of a soft friable structure was found to be accurate in 91 per cent of cases. Diagnosis based on the presence of a firm plum-like structure or the disappearance of a previously identified follicle at a given site was 60 per cent accurate. In cases of rectal diagnosis of non-ovulation 38 per cent had actually ovulated based on a rise in progesterone more than 1 ng/ml and a further 19 per cent showed a rise in progesterone by 24 h after the diagnosis. The use of hCG may improve conception rates by synchronisation of ovulation and mating and where rectal palpation of the ovaries remains the only basis for timed mating.