E. Gaspar-López

Antler mineral composition of Iberian red deer Cervus elaphus hispanicus is related to mineral profile of diet

Previous studies have suggested that antlers are costly bone structures whose mineral composition may change depending on physiological and other factors. This study examined whether nutrition variation associated with deer management influences antler mineral composition and structural characteristics of whole antler. Mineral distribution and bone structure were examined in antlers from two groups of adult Iberian red deer Cervus elaphus hispanicus Hilzheimer, 1909. They were kept under different feeding regimes at an experimental deer farm and a game estate in southeastern Spain. Protein and mineral contents differed between the diet of captive deer and that of deer in the wild. Significant differences were found for Na, Mg, K and protein. Antler composition seems to reflect the diet, as antlers of deer differed in protein, Na, Mg and K, but not in total mineral content, Ca, Fe or Zn. Thus, management conditions related to nutrition are reflected on antler composition.

Age-related body weight constraints on prenatal and milk provisioning in Iberian red deer (Cervus elaphus hispanicus) affect allocation of maternal resources.

Maternal phenotypic characteristics can influence key life history variables of their offspring through maternal effects. In this study, we examined how body size constraints on maternal weight in yearling and subadult compared to adult hinds (age class effects) affected prenatal (calf birth weight, calf to hind weight ratio) and postnatal (milk) provisioning of Iberian red deer calves. Age correlated with all prenatal and postnatal investment traits except calf gains, although correlations were weaker than those with maternal weight. Once the effect of linear increase in weight with age was removed from models, yearlings showed additional reductions in calf birth weight, calf gains, and milk provisioning. The low-calf birth weight might increase the risk of calf mortality during lactation, as this occurs primarily during the first day of life and is strongly related to birth weight. Yearlings showed a greater prenatal allocation of resources in terms of greater calf to hind weight ratio probably as an extra effort by yearling mothers to balance calf neonatal mortality. It might compensate young mothers to produce low-quality calves while still growing rather than waiting for the uncertain possibility of surviving to the next reproductive season.

Lactation growth influences mineral composition of first antler in Iberian red deer Cervus elaphus hispanicus

Abstract Deer antlers are bony fighting structures which are unique in that they are both easily accessible for analysis and that they are grown every year; thus, they make up good models for the study of bones. Previous studies have shown that antler bone composition is related to the external quality (antler size and weight) and the mechanical quality of the antlers, and that it reflects mineral nutrition and early growth. Because one of the main nutritional factors influencing early growth is maternal milk production and composition, and because lactation plays an important role in post-weaning growth, we set out to examine whether milk yield and composition are correlated with the mineral composition of spike antlers of 22 yearling Iberian red deer Cervus elaphus hispanicus. Total milk protein yield was positively associated with ash, Ca and P content in antler, inversely with K content, but no relationship was found for Na, Mg, Fe or Zn. This association was evidently exerted through an increase in calf growth during lactation, because in the model, the inclusion of calf weight gain up to week 18 (approximately the age at weaning) rendered milk production and composition non-significant. However, this correlation was not observed for the minor minerals Na, Mg, Fe and Zn. Gains during lactation, but not between lactation and antler growth, influenced the composition of major minerals. Manipulating milk quality could not only affect general calf growth, but also antler quality and very likely the quality of other bones, as well as mechanical performance, which is linked to ash or Ca content.

Seasonal variations in plant mineral content and free-choice minerals consumed by deer

The aim of this study was to assess the seasonal differences in mineral contents of plants often consumed by wild red deer located in a fenced game estate, south-eastern Spain. Forage plants were sampled throughout 1 year and analysed for macro and trace mineral concentrations. We also offered a cafeteria set of supplemented minerals to assess whether: (i) intake reflected seasonal reductions in plant content of specific minerals; or (ii) intake of mineral supplements responded to increased deer demand of minerals as a result of greater seasonal needs likely arising from lactation, antler growth or skeletal growth. Although no significant seasonal trend was found in mineral distributions of plants, our study suggested that concentrations of K, Mg, Mn, Na, P, Cu and Zn were usually low in plants available to, and consumed by, deer in the study area. In addition, Cu concentration was marginally deficient when compared with the published requirements for other subspecies of red deer. The cafeteria study showed that free-ranging deer had a strong preference for sodium compounds and zinc sulfate, a much weaker attraction to calcium iodate, and no intake in calcium phosphates, Mg and Fe. Consumption of supplemented minerals by deer was maximum in spring and summer and moderate during autumn and winter. Rather than increasing intake of minerals in response to their content in plants, deer may be responding to increased metabolic requirements during antler growth, late gestation and early lactation. Supplementation of mineral compounds is recommended, particularly in the spring–summer period, when the physiological activity is high.

ENSO affects sex ratio progeny in captive Iberian red deer despite a steady feeding regime

Climate variability greatly affects animals through direct and indirect effects. Animals with slow reproductive adaptation to ecological changes such as large mammals are likely to have evolved mechanisms to anticipate early such impacts of climate variability on the environment. One of the adaptive mechanisms between reproductive costs and benefits in mammals affects parental investment through biases in sex ratio. Deer might be likely to show an early detection of climate variability because conception takes place in early autumn, but the main raising cost in deer concerns lactation, which takes place at the end of the following spring. The aim of this paper is to assess whether there is a relationship between global indices of climate variability such as El Niño-Southern Oscillation (ENSO) and sex ratio of a captive population of deer. Results showed that there was a negative correlation (r=−0.65) between sex ratio and ENSO indices between 1996 and 2008. El Niño enhances drier conditions during the summer in the Iberia Peninsula, which in turn favours a female bias. Results also suggest that the mechanism of early detection of climate variability exerts a strong effect on female reproductive physiology because the long-term stability of food resources in our setting has not markedly reduced it.

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 taken and analysed. After adjusting for age and body mass, dominance ranking showed a significant negative effect (ie, lower values in dominant hinds) on white blood cell (WBC) count, haemoglobin and haematocrit. Our results are similar to those reported for stressed individuals due to physical immobilisation, but do not support the predicted enhanced erythropoiesis due to higher levels of androgens. The results for WBC numbers may also reflect that subordinate hinds must allocate a higher amount of resources to immunity as a result of injuries incurred from dominant hinds, while simultaneously facing restricted access to food sources. For red blood cell (RBC) counts, the results may be due to subordinate hinds likely needing increased haematocrit and haemoglobin levels for fast flight responses. Our data show that social rank influences haematologic profile, and thus it should be considered when correctly interpreting blood analyses in social cervid species.

Hind body condition and weight in primiparous of Iberian red deer (Cervus elaphus hispanicus) with one, two or three years old at mating

Abstract Several studies of mammals have examined the fitness consequences of the age of primiparity, due to primiparous hinds face a trade-off between reproductive effort at first breeding and body growth. Physical condition of hinds is the most important factor determining whether individuals became pregnant. In fact, in yearling hinds there is a positive effect of premating body weight on conception and the onset of puberty depends on her body weight. In addition reproductive effort at first breeding should reduce the amount of body reserves available for growth and maintenance, potentially reducing residual reproductive value. This study examined 103 primiparous hinds of Iberian red deer (Cervus elaphus hispanicus) with one (n=75), two (n=21), or three (n=7) years old at mating, from 1998 up to 2006. They were kept in a 30000 square meters opendoor in the Experimental Farm of Castilla-La Mancha University in Albacete (38° 57′ 10″ North, 1° 47′ 00″ West and 690m above sea level) and they had ad libitum access to food and water. Hinds were weighed weekly on a ± 50g electronic balance, and then they were driven to a small handling box to asses their body condition. General Linear Models were used to examine the effect of the age at first breeding on the following variables: hind weight at mating, precalving and postcalving, weight gain during gestation, weight lost at calving, mating body condition and calf birth weight. The GLMs performed showed a significant effect of hind age at first breeding on mating weight (coefficient: 7.15 ± 1.67; P <0.001), precalving weight (coefficient: 6.31 ± 1.83; P <0.01), and postcalving weight (coefficient: 6.17 ± 1.59; P <0.001), improving all of these variables with hind age. Mating body condition was affected by hind age (P <0.05) too, being greater in primiparous with one year at mating than in those hinds with two or three mating years. Also, the monthly trend in body condition during gestation was different in the three groups of hinds; in hinds with one year at mating body condition improved during two first months, beginning to decrease in the third month of gestation while in the other groups of hinds it was improving practically during all gestation. On the other hand, the minimum mating weight observed to achieve a successful reproduction was 53.5, 58.5, or 71kg in primiparous with one, two or three mating years respectively. Finally, no differences were observed between groups in weight gain during gestation, weight lost at calving or calf birth weight.