Effects of temperament during handling and social rank on the blood biochemical parameters of common eland (Taurotragus oryx)

Large herbivores are subject to handling and social stress in captivity. These may affect blood biochemical values, which motivated this research. Twelve healthy common eland (Taurotragus oryx) were monitored for 12 months. The animals were handled monthly, and blood samples were collected. Samples from every second month were analysed for 14 blood biochemical parameters. Temperament throughout the handling, as the summation of various behavioural responses, was calculated as a proxy of the stress generated during handling. Social behaviour was recorded each month, and the agonistic interactions were used to calculate the social rank, which was considered a proxy of social stress. Generalised Linear Mixed Models were designed to test the effects of temperament and social rank on the blood biochemical parameters while keeping sex, age, body condition, and body weight as covariates. The results show that the temperament during handling influences blood levels of albumin, alkaline phosphate, blood urea nitrogen, glucose, total bilirubin, and total protein; however, social rank has little influence, affecting just albumin. The ranges observed in the values of these biochemical parameters were still within their reference intervals, implying the absence of pathology or physiological problems during the study. The results suggest that blood biochemical values of physically restrained common eland should be carefully interpreted, even in animals already habituated to routine handling. On the contrary, social rank has low effects on the blood biochemical parameters.

Higher dominance position does not result in higher reproductive success in female beef cattle

The aim of this study was to investigate whether beef cows that achieve higher dominance status than their age-mates have prolonged reproductive life, increased number of offspring born and weaned, and/or heavier BW of the offspring. We also assessed whether maternal dominance rank affects the offspring sex ratio. We recorded data on 309 potential deliveries of female beef cows with known dominance status in a seasonally pastured herd over a 14-yr period and linked them with yearly records of dominance status of the cows assessed around feeding. We did not find any effect of age-corrected dominance index on cow reproductive success measured as delivery or weaning success, calf birth weight or weaning weight, survival of the cow to the following reproductive season, or sex of the conceived calf (generalized linear models, > 0.05). In conclusion, the results indicate that in a typical situation of pastured beef cattle, there might be no selection for individual striving to achieve higher dominance status.

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.

Does nutrition affect bone porosity and mineral tissue distribution in deer antlers? The relationship between histology, mechanical properties and mineral composition

It is well known that porosity has an inverse relationship with the mechanical properties of bones. We examined cortical and trabecular porosity of antlers, and mineral composition, thickness and mechanical properties in the cortical wall. Samples belonged to two deer populations: a captive population of an experimental farm having a high quality diet, and a free-ranging population feeding on plants of lower nutritive quality. As shown for minerals and mechanical properties in previous studies by our group, cortical and trabecular porosity increased from the base distally. Cortical porosity was always caused by the presence of incomplete primary osteons. Porosity increased along the length of the antler much more in deer with lower quality diet. Despite cortical porosity being inversely related to mechanical properties and positively with K, Zn and other minerals indicating physiological effort, it was these minerals and not porosity that statistically better explained variability in mechanical properties. Histochemistry showed that the reason for this is that Zn is located around incomplete osteons and also in complete osteons that were still mineralizing, whereas K is located in non-osteonal bone, which constitutes a greater proportion of bone where osteons are incompletely mineralized. This suggests that, K, Zn and other minerals indicate reduction in mechanical performance even with little porosity. If a similar process occurred in internal bones, K, Zn and other minerals in the bone may be an early indicator of decrease in mechanical properties and future osteoporosis. In conclusion, porosity is related to diet and physiological effort in deer.

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.

Do drastic weather effects on diet influence changes in chemical composition, mechanical properties and structure in deer antlers?

We attempted to determine why after an exceptionally hard winter deer antlers fractured more often than usual. We assessed mechanical properties, structural variables and mineral composition of deer antlers grown in a game estate (LM) after freezing temperatures (late winter frosts, LWF), which resulted in high incidence of antler fractures despite being grown later in the year, and those grown after a standard winter (SW). Within each year, specimens from broken and intact antlers were assessed. LWF was associated with reduced impact energy (U) and somewhat reduced work to peak force (W), Young's modulus (E) and physical density, as well as cortical thickness. LWF was associated with considerably increased Si and reduced Na. In each year, broken antlers had lower Mn, P and physical density, and they had more Na and B than unbroken antlers. Because no such effect was found in farmed deer fed whole meal, and because freezing in plants usually produces an increase in Si content, which in turn reduces Mn, it is likely that LWF produced a diet rich in Si and low in Mn. Because antlers are grown transferring calcium phosphate from the own skeleton and Ca/P levels were slightly reduced, it seems likely that Mn reduction may have increased antler fractures. A comparison between farm deer and those in another game estate (LI) also shows a link between lower Mn content and lower W. Thus, small changes in minor bone minerals, probably induced by diet, may have marked effects in mechanical properties of bone.

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.

The mechanical properties of red deer antler bone when used in fighting

We assessed the hydration state of antlers and its effect on antler mechanical properties compared with wet femur. Red deer antlers were removed from the head at various times, from a few days after velvet shedding till late in the season, and weighed weekly until after casting time. Antlers cut just after losing their velvet lost weight rapidly in the first few weeks, then settled down and changed weight very little, the latter changes correlating with air relative humidity. Antlers cut later showed little weight change at any time. The water content of cortical and trabecular parts of the contralateral antler was assessed after cutting. Most of the weight loss was from the cancellous, not the cortical, part of the antler. Wet and dry specimens from the antlers, and wet specimens from deer femora, were tested mechanically. Compared with wet bone, wet antler had a much lower modulus of elasticity and bending strength, but a higher work to fracture. Compared with wet bone, dry antler showed a somewhat lower Young's modulus, but a considerably higher bending strength and a much higher work to fracture. The impact energy absorption of dry antler was much greater than that of wet bone. In red deer, the antler is effectively dry during its use in fights, at least in southern Spain. In addition, dry antler, compared with ordinary bone, shows mechanical properties that suit it admirably for its fighting function.

Effect of milk minerals on calf gains and sex differences in mineral composition of milk from Iberian red deer (Cervus elaphus hispanicus)

Milk mineral content has received little attention in studies focusing on milk nutrient effects on offspring growth. This study examines calf growth in Iberian deer and compares the influence of milk minerals, other nutrients, and lactation variables relevant for growth to discern the relative weight of each factor. In addition, because Iberian deer hinds are the first mammal found to produce different milk for sons and daughters, the present study examines whether there are also sex differences in milk mineral composition. Concentrations and yields of Ca, P, Mg, Na, K, Fe, and Zn in milk of 46 red deer hinds were monitored through 18 weeks of lactation. Calf growth was influenced by Ca and P percent, and total Fe production. Milk for males had a lower content in Ca and P, a greater content of K, and Mg, whereas no sex effects were found in Na, Fe, or Zn percentages. Higher percentages in Ca and P for daughters might constitute a compensatory response, as daily production was not biased towards females in Ca or P, whereas in the latter and all the other minerals daily production was greater for heavier calves, which are usually males. In conclusion, milk mineral content and production influence calf growth even after controlling for other important lactation variables and nutrients, and they show effects and interactions more complicated than expected.

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.

Does chemical composition of antler bone reflect the physiological effort made to grow it?

In a previous study, antler bone chemical composition was found to differ between base and tip. If such variation is in part due to the physiological effort made to grow the antler, composition trends should differ between antlers from deer population differing in mineral or food availability, or body reserves. To assess this, we examined cortical thickness and bone composition along the antler shaft, and compared trends between antlers from two populations: captive, well-fed, health-managed deer (n=15), and free-ranging deer with lower food quality and no health treatment (n=10). Significant and clear divergent trends supporting greater physiological exhaustion in free-ranging deer and high or moderate predictive models were found for cortical thickness (R(2)=61.8%), content of Na (R(2)=68.6%), Mg (R(2)=56.3%), K (R(2)=40.0%), and Zn (34.6%); lower predictive power was found for protein (R(2)=25.6%) and ash content (R(2)=19.5%); and poor predictive power was found for Ca (R(2)=4.3%), Fe (R(2)=11.1%), and Si (R(2)=4.7%). A second part of the study assessed similar antler structures grown at the beginning (brow tine) and end (top tine) of antler growth within captive deer. Greater cortical thickness and ash content was found for brow tine, as well as a smaller protein, K and Mg content. In contrast, no difference was found for Ca, Na, Zn, Fe or Si. The results suggest that thickness and mineral composition reflect the physiological effort made to build antler bone.

Differential response of chick liver and brain membranes to short ethanol treatment

The effect of 60 hr ethanol ingestion on lipid composition of liver and brain membranes from 2-day-old chicks was investigated. Analysis of hepatic membrane cholesterol shows that ethanol induced a slight increase in microsomes exclusively due to free cholesterol while mitochondria was not affected. In brain, both fractions showed a clear increase in their cholesterol content, while a high decrease was observed in myelin. Free cholesterol was also the main responsible for the changes found in brain. The ethanol-treated animals showed an alteration in their phospholipid composition exclusively in brain microsomes and myelin. Despite all these changes, the values of cholesterol/phospholipid molar ratio in both liver and brain membranes remained unaltered after short ethanol treatment. Our results indicate that neonatal chick brain membranes appears to be especially sensitive to the presence of ethanol.

The fatty acid composition of mitochondria, microsomes and myelin from neonatal chick brain. Susceptibility to short and chronic treatment with ethanol

Short-term and long-term effects of ethanol on the fatty acid composition of mitochondrial, microsomal and myelin fractions in brain have been investigated. Microsomal membranes were not modified by treatment for 60 hr, while in mitochondrial membranes there was a significant decrease in arachidonic and docosahexaenoic acids, responsible for the decrease in the double-bond index. A clear decrease in the 18:1/18:0 ratio was found in myelin after short-term treatment, whereas no significant variations were observed in the other subcellular membranes under the same conditions. On the other hand, chronic exposure to ethanol for 18 days induced a significant increase in oleic and docosahexaenoic acids in microsomal membranes. However, no significant changes were detected in the composition of fatty acids of mitochondrial membranes after 18 days of administration of ethanol. Contrary to that found with short-term treatment, a significant increase was observed in the 18:1/18:0 ratio of the myelin fraction after chronic consumption of ethanol. These results suggest that alcohol intoxication of neonatal chicks induces different modifications in composition of fatty acids of different membranes in the brain, those observed in the myelin fraction being specially important.

Alterations induced by chronic ethanol treatment on lipid composition of microsomes, mitochondria and myelin from neonatal chick liver and brain

The effect of 18 days ethanol consumption on the lipid composition of microsomes, mitochondria and myelin have been studied in neonatal chick liver and brain. Neither cholesterol nor phospholipid content was modified in both liver microsomes and mitochondria. However, cholesterol content of brain microsomes, mitochondria and myelin was clearly increased, mainly due to an enhancement of free cholesterol. Likewise, ethanol consumption induced a clear increase of phospholipid content in brain mitochondria and myelin. As a consecuence of these changes, the cholesterol/phospholipid molar ratio strongly increased only in the myelin fraction. The myelin phospholipid composition markedly varied by ethanol treatment. Our results indicate that the maximal modifications were induced by ethanol in membranes with a high cholesterol content, suggesting that differences in the chemical composition of membranes could be responsible for differences in the response to the ethanol consumption.

Ethanol sensitivity and fatty acid composition of chick liver mitochondrial and microsomal membranes

Fatty acid composition of hepatic mitochondrial and microsomal membranes was studied in 2-day-old chicks exposed to ethanol for 60 h (short treatment) or 18 days (chronic treatment). Short ethanol treatment induced in mitochondria an increase in the 18:1/18:0 ratio as a consequence of both an increase in the percentage of oleic and a decrease in that of stearic acid. Likewise, a clear decrease in the polyunsaturated fatty acids and in the 20:4/18:2 ratio was found in mitochondria after short ethanol administration. Microsomal membranes were practically unaffected by this treatment. However, chronic ethanol exposure produced a significant increase in the percentages of polyunsaturated fatty acids in both mitochondria and microsomes as well as a decrease in the 18:1/18:0 ratio. These results suggest that delta 9 desaturase modifies its activity in response to ethanol treatment with a different pattern to those showed by delta 6 and delta 5 desaturase activities.