Development of body condition in hinds of Iberian red deer during gestation and its effects on calf birth weight and milk production

Risk-taking neonates do not pay a survival cost in a free-ranging large mammal, the fallow deer (Dama dama)

Recent debate has focused on whether variation in personality primarily reflects variation in resource allocation or resource acquisition of individuals. These two mechanisms predict different relationships between personality and survival. If personality mainly reflects variation in resource allocation, then bold (i.e. risk-taking) individuals are expected to live shorter lives, whereas the opposite pattern is expected with resource acquisition. Here we studied the relationship between neonate personality and early-life survival in 269 juveniles of a population of fallow deer (Dama dama). We found that bolder individuals paid no apparent survival cost. Interestingly, among-individual differences in the physiological response at capture (heart rates, which covary with the behavioural response, i.e. latency to leave) were linked to survival, where individuals with lower heart rates when handled by humans had a higher probability of early-life survival. This suggests that bolder individuals may be of higher state than their shyer counterparts. As the first study linking neonate personality to survival in a free-ranging mammal, we provide novel insights into drivers behind early-life individual variation.

Risk-taking neonates do not pay a survival cost in a free-ranging large mammal, the fallow deer (Dama dama)

Recent debate has focused on whether variation in personality primarily reflects variation in resource allocation or resource acquisition of individuals. These two mechanisms predict different relationships between personality and survival. If personality mainly reflects variation in resource allocation, then bold (i.e. risk-taking) individuals are expected to live shorter lives, whereas the opposite pattern is expected with resource acquisition. Here we studied the relationship between neonate personality and early-life survival in 269 juveniles of a population of fallow deer (Dama dama). We found that bolder individuals paid no apparent survival cost. Interestingly, among-individual differences in the physiological response at capture (heart rates, which covary with the behavioural response, i.e. latency to leave) were linked to survival, where individuals with lower heart rates when handled by humans had a higher probability of early-life survival. This suggests that bolder individuals may be of higher state than their shyer counterparts. As the first study linking neonate personality to survival in a free-ranging mammal, we provide novel insights into drivers behind early-life individual variation.

Pelt Biting as a Practical Indicator of Social and Environment Stress in Farmed Red Deer

Simple Summary

Agonistic behavioural interactions play a decisive role in the competition for food, space, mating opportunities, and establishing social rank. We propose the use of the number of bites on the pelt of red deer as an index of agonistic interactions between group members. Using behavioural data from a 14-year time series of a captive population of Iberian red deer (Cervus elaphus), we found that deer that were of higher social rank, heavier, living in smaller groups, or under no heat stress conditions suffer less pelt bites than those of lower social rank, lighter, living in bigger groups, or under heat stressing conditions. Hinds that gave birth earlier in the parturition period suffered less pelt biting than those that gave birth around the peak of the parturition season. Pelt biting is useful to identify management situations in which deer welfare could be at stake.

Abstract

Agonistic behavioural interactions play a decisive role in the competition for food, space, mating opportunities, and establishing social rank. We used pelt biting (number of bites on an animal’s body) as a proxy for assessing the intensity of agonistic animal interactions and how it responded to social, population, and heat stress factors. We modelled a 14-year time series of pelt biting records and observational data of agonistic interactions on a population of captive Iberian red deer (Cervus elaphus). We found that (i) the higher the social rank of deer, the lower the number of pelt bites received; (ii) increasing heat stress conditions caused deer to suffer more pelt bites; (iii) males received more bites than females; (iv) the heavier the deer, the lower the number of bites on their bodies; (v) the bigger the group, the more bites exhibited on its members; (vi) deer 5–6 years old suffered greater rate of pelt biting than younger or older deer; and (vii) hinds that gave birth earlier in the parturition period suffered less pelt biting than those that gave birth around the peak of the parturition season (p < 0.01 for all effects). Pelt biting is useful to predict management situations in which deer welfare could be at stake.

Evaluation of factors inducing variability of faecal nutrients in captive red deer under variable demands

Based on the assumption that dietary and faecal nitrogen correlate, the number of studies using faecal samples collected in the wild to understand diet selection by wild herbivores and other ecological patterns has been growing during the last years, especially due to the recent development of cheap tools for analysis of nutrients like Near-Infrared Reflectance Spectroscopy (NIRS). Within the annual reproductive cycle, cervids (members of the family Cervidae) face strong seasonal variations in nutritional demands, different for hinds (gestation and lactation) and stags (antler growth) and reflected in differential patterns of seasonal diet selection. In this study we aimed to quantify how pasture availability, season and individual factors like sex, age, reproductive status, body mass and body condition affect faecal nutrients in captive red deer with the goal of understanding how these factors may influence the interpretation of results from samples obtained in the wild with little or no information about the animals who dropped those faeces. We used NIRS for analysing nitrogen, neutral and acid detergent fibres in faeces. The relative influence of some individual factors like pregnancy was low (around 4%), while age and weight may induce a variability up to 18%. The presence or absence of pasture contributed to a variability around 13%, while the season contributed to an average variability around 17% (and up to 21% in certain situations). This high variability in faecal nutrients was observed in a controlled setting with captive animals and controlled diets. Thus, in natural situations we suspect that there would be even greater variation. According to the results, we recommend that preliminary research with captive animals of the species of interest should be conducted before collecting samples in the wild, which should help in the interpretation of results.

Rainfall decrease and red deer rutting behaviour: Weaker and delayed rutting activity though higher opportunity for sexual selection

In the last decades, climate change has caused an increase in mean temperatures and a reduction in average rainfall in southern Europe, which is expected to reduce resource availability for herbivores. Resource availability can influence animals' physical condition and population growth. However, much less is known on its effects on reproductive performance and sexual selection. In this study, we assessed the impact of three environmental factors related to climate change (rainfall, temperature and vegetation index) on Iberian red deer Cervus elaphus hispanicus reproductive timing and sexual behaviour, and their effects on the opportunity for sexual selection in the population. We measured rutting phenology as rut peak date, the intensity of male rutting activity as roaring rate, and the opportunity for sexual selection from the distribution of females among harem holding males in Doñana Biological Reserve (Southwest Spain), from data of daily observations collected during the rut over a period of 25 years. For this study period, we found a trend for less raining and hence poorer environmental conditions, which associated with delayed rutting season and decreased rutting intensity, but that appeared to favour a higher degree of polygyny and opportunity for sexual selection, all these relationships being modulated by population density and sex ratio. This study highlights how climate change (mainly rainfall reduction in this area) can alter the conditions for mating and the opportunity for sexual selection in a large terrestrial mammal.

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 Summary

The 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.

Abstract

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.

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.

Effects of Mn supplementation in late-gestating and lactating red deer (Cervus elaphus hispanicus) on milk production, milk composition, and calf growth

This study describes the effects of Mn supplementation of 20 late-gestating and lactating Iberian red deer (Cervus elaphus hispanicus) females (hinds) fed a balanced diet on milk production and milk composition over the lactation period. Body weight of their calves at birth and at weaning was also evaluated. In addition, the effect of lactation stage was studied. For these purposes, 2 groups of hinds, one composed by 12 individuals (experimental) and the other by 8 individuals (control) were compared. Experimental hinds were s.c. injected weekly with Mn (2 mg Mn/kg BW) from day 140 of gestation until the end of lactation (week 18; forced weaning by physical separation). Control hinds were injected with a physiological saline solution with the same volume and at the same frequency as the experimental group. Serum Mn content of hinds was assessed just before the first Mn injection and at week 10 of lactation to assess whether the injected Mn increased Mn concentrations in blood. No differences were observed for BW of calves at birth but calves whose mothers were injected with Mn tended (P = 0.07) to have greater gain of BW from birth to weaning in proportion of BW at birth compared to calves from control hinds. In addition, supplementation with Mn increased (P ≤ 0.05) daily milk production by 10.2%, milk fat content by 11.2%, and total fat yield by 17.8%. Also, milk from hinds supplemented with Mn had more Ca (P < 0.001) and P (P < 0.05) than milk from control hinds. Manganese supplementation did not influence Mn serum content when blood was analyzed at week 10 of lactation, but increased the Mn content of milk by 18.3% (P < 0.001). Lactation stage affected (P < 0.001) fat, protein, lactose, and DM. Their contents increased as lactation proceeded, and protein was substituted by fat. Therefore, results suggest that Mn supplementation of hinds is recommended, even when they are fed a balanced diet, to increase milk production and the content of fat, Ca, P, and Mn of milk.

Between-year vocal aging in female red deer (Cervus elaphus)

OBJECTIVES

Studying animal vocal aging has potential implication in the field of animal welfare and for modeling human voice aging. The objective was to examine, using a repeated measures approach, the between-year changes of weight, social discomfort score (bites of other hinds on hind pelt), body condition score (fat reserves) and acoustic variables of the nasal (closed-mouth) and the oral (open-mouth) contact calls produced by farmed red deer hinds (Cervus elaphus) toward their young.

RESULTS

Repeated measures ANOVA revealed that with an increase of hind age for 1 year, the acoustic variables of their nasal contact calls (the beginning and maximum fundamental frequencies, the depth of frequency modulation and the peak frequency) decreased, whereas in their oral contact calls only the end fundamental frequency decreased. Duration and power quartiles did not change in any call type. Body weight and body condition score increased between years, whereas discomfort score decreased. Results of this study revealed directly the short-term effects of aging on the acoustics of the nasal contact calls in the same hinds. This study also confirmed that elevated emotional arousal during emission of the oral contact masks the effects of aging on vocalization in female red deer.

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

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

Seasonality of fecal androgen and glucocorticoid metabolite excretion in male goral (Naemorhedus griseus) in Thailand

There is no information on the endocrinology of Chinese goral (Naemorhedus griseus), a high priority species for captive breeding and reintroduction in Thailand. This study characterized fecal androgen and glucocorticoid metabolites in male goral at Omkoi Wildlife Sanctuary to investigate seasonal relationships. Fecal samples were collected 3 days/week for 1 year from eight adult males. Mean androgen metabolite concentrations were greater (P<0.05) during the rainy season (289.82±9.18ng/g) and winter (224.09±11.97ng/g) compared to the summer (195.48±8.23ng/g), and were related to breeding activity. A similar pattern was observed for glucocorticoid concentrations (22.10±0.72ng/g compared to 21.98±0.98ng/g compared to 15.30±0.48ng/g), respectively, and this resulted in a positive correlation between the two hormones (P<0.05). There also were positive correlations between fecal androgen metabolite concentrations and temperature (P<0.05) and day length (P<0.05). In summary, this is the first study to assess endocrine function in male goral, and results showed seasonal variation in testicular and adrenal steroidogenic function, with greater activity in the rainy season and winter. Given that resources for captive male goral are consistent throughout the year, reproduction may be regulated primarily by photoperiod in this species.

Factors affecting antler investment in Iberian red deer

Antler constitutes such a costly trait that the skeleton of the deer undergoes a process similar to osteoporosis to meet the high demands of mineral deposition in the antler. The allometric relationship between antler and body size is one of the oldest known. However, no study has assessed the proportion that antlers constitute with regard to the skeleton (from which most of the material is drawn), nor which factors influence this investment. To assess this, we studied 171 males (aged 1–5 years), determined their antler and bodyweights and scored their body condition. Then we calculated antler investment as antler weight relative to estimated skeletal weight. Results showed that antler investment in males ≥2 years old (i.e. excluding yearlings) depended on age rather than the whole bodyweight or body condition. Antler investment increased from 6% in yearlings to 35% in 5-year-old males, with a mean of 19%. A GLMM showed that in males ≥2 years old, within age, the heavier the male and the better the body condition at the start of antler growth, the greater the investment in antlers. In yearlings, antler investment did not depend on bodyweight or body condition. In conclusion, antler weight relative to skeleton weight is a good method to assess antler investment. This investment is influenced by age and, in males ≥2 years old, also by bodyweight or condition at the start of antler growth.

Can Iberian red deer (Cervus elaphus hispanicus) discriminate among essential minerals in their diet?

Optimal foraging predicts that animals should be able to assess the content of important nutrients in food. Ungulates discriminate salt and P, but discrimination of other minerals is controversial even though they are also essential and often limiting. Animal scientists have explained this taste through palatability, which predicts the same pattern of discrimination for calves and hinds and greater consumption by the latter. Social learning may also be involved, predicting a correlation between mother and calf and less consumption by the latter. The present study examines the consumption behaviour of free-choice supplemented minerals by hinds and calves of Iberian red deer (Cervus elaphus hispanicus) to discern between these hypotheses. Behavioural indices of intake correlated with actual mineral consumption (P < 0.001). Mother and calf behavioural indices correlated only for salt-mixed minerals. Calves showed overall behavioural indices of consumption greater than hinds (P < 0.01 and P < 0.001), and also for all single supplements except NaCl, as expected from growth needs and in contrast to the palatability hypothesis. Calves showed a greater consumption of CuSO(4) and lower of Na(2)SeO(3) than pure salt. Hinds showed a different pattern, ingesting lower amounts of all minerals except CuSO(4) and salt. Additional analyses also showed discrimination between minerals unmixed with salt, such as CaHPO(4) and CaCO(3) (P = 0.012 and P = 0.020). The greater intake of growing calves and the different consumption patterns for hinds and calves suggest that deer can discriminate among minerals, and that they do not consume minerals for their palatability or driven by social learning. Therefore, deer may be selecting minerals according to nutritional requirements.