Concentration of Macroelements and Trace Elements in Farmed Fallow Deer Antlers Depending on Age

The mineral content of the antlers reflects the nutritional status and specific stage of bone growth in cervid males. Therefore, this research aimed to analyze the concentration of Ca, P, Mg, K, Na, Li, V, Cr, Mn, Co, Cu, Zn, Se and Mo in three characteristic antler positions selected based on the observation of fights between males. These were compared between farmed fallow deer (Dama dama) of different ages. The mineral compositions of tissues were analyzed using inductively coupled plasma mass spectrometry. The highest mean concentrations of macroelements (except K) were recorded in the youngest animals aged 2 or 3 years in the proximal position of the antlers. With age and distance from the skull, Ca, P, Mg and Na contents decreased, while K increased. Higher mean concentrations of most trace elements (Cr, Mn, Co, Cu, Zn) were recorded in 3-year-old animals in antler distal positions. With an increase in the age, body mass and antler mass of fallow deer, the concentration of Ca, P, Mg, K, Mn, Cu and Zn decreased (−0.414 ≤ R ≤ −0.737, p < 0.05) in the studied tissue, whereas Li increased (0.470 ≤ R ≤ 0.681, p < 0.05). The obtained results confirm that the antlers’ chemical composition changes with age, also changing the Ca:P ratio.

The Mineral Composition of Bone Marrow, Plasma, Bones and the First Antlers of Farmed Fallow Deer

An adequate supply of essential nutrients is particularly important during the skeletal growth and development of young deer, especially in males, who build new antlers each year. The aim of the research was to analyze the levels of 21 mineral elements (including the bulk elements: Ca, P, Mg, K, Na; trace elements: Li, Cr, Mn, Co, Cu, Zn, Se, Mo; and toxic elements: Be, Al, As, Cd, Sb, Ba, Pb, Ni) in the bone marrow, plasma, bones, and first antlers of farmed fallow deer (Dama dama). The mineral compositions of tissues were analyzed using inductively coupled plasma mass spectrometry. Higher concentrations of Ca, P, Mg, Cr, Zn, Se, Al, Ba and Ni were found in bone marrow than in plasma. The highest concentrations of Ca, P and Ba were recorded in fallow deer bone, while the highest concentrations of Mg, K, Na, Li, Cr, Mn, Co, Cu, Zn, Se, Mo, Be, Al, As, Sb, Pb and Ni were found in the antlers. Moreover, the research showed a significant negative relationship between Ca and Cd, and between Ca and Pb, and P and Pb (rS = −0.70, rS = −0.80, and rS = −0.66, respectively; p < 0.05) in the tissues.

Comparison of the accumulation of macro- and microelements in the bone marrow and bone of wild and farmed red deer (Cervus elaphus)

Background

The cells of the entire body, including the skeletal system, especially of young animals, may derive from the bone marrow in which they multiply. Therefore, it is important to assess whether the diet and quality of life of deer have a significant impact on the elemental composition of bone and bone marrow, which can directly affect their health and growth. The aim of this study was to determine the concentrations of macro- (Ca, calcium, P, phosphorus, Mg, magnesium, K, potassium, Na, sodium) and microelements (Li, lithium, Cr, chromium, Mn, manganese, Co, cobalt, Cu, copper, Zn, zinc, Se, selenium, Mo, molybdenum, and Sn, tin) accumulated in the bone marrow and bones of deer (Cervus elaphus). The study was carried out on 15 young stags divided into two groups: farmed and wild animals. The concentrations of macro- and microelements were analysed using the inductively coupled plasma mass spectrometry technique. This research expands our knowledge on this topic, which so far has not been extensively studied.

Results

The mean content of K, Na, Zn and Se in the bone marrow of farmed animals was significantly higher than in wild deer, whereas the mean content of Ca, P, Mg, K, Na and Li in the bones was higher in wild animals than in farmed individuals (p < 0.05). In addition, the mean concentration of Cr, Mn, Cu, Se and Mo in the bones of the analysed animals differed significantly (p < 0.05) and was higher in the farmed deer. The mean concentration of Se in the bone marrow of wild deer decreased with the increase of the body weight (p < 0.05). In turn, the mean content of Mn in the bone marrow and of Mo in the bones of the animals was significantly positively correlated with the animals’ body weight (p < 0.05).

Conclusions

The obtained results indicated different levels of micro- and macro-components in the body of farmed and wild deer, though without clear and strong variations. Generally, the higher level of macronutrients in the bones of wild deer may be related to the higher physiological importance of these minerals for life activities in the natural environment and to the limited supply of balanced food. On the other hand, the higher levels of microelements in the tissues of farmed animals may result from their significantly better nutritional status in the first year of life, achieved through appropriate nutrition as well as diet supplementation of adult females.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-03041-2.

Effects of supplementation with different levels of calcium and phosphorus on mineral content of first antler, bone, muscle, and liver of farmed fallow deer (Dama dama)

Nutrition is one of the main factors influencing physiological processes, e.g., growth and antler development, in Cervidae. The aim of this study was to demonstrate a possible effect of supplementation with different levels of calcium (Ca) and phosphorus (P) on the mineral composition of antlers and bones, and its effect on the content of macroelements — Ca, potassium (K), magnesium (Mg), sodium (Na), and P — in the muscle tissue, liver, and blood of farmed fallow deer fawns. The results show a positive effect of increased doses of Ca and P on body weight at the age of 14 mo. Additionally, there was a significant increase in the content of Ca, Mg, Na, and P in antlers and Ca, Na, and P in bones. The muscle tissue was characterised by a significant increase only in the content of Na, whereas Ca, K, and P levels increased significantly in the liver. In turn, the serum P content decreased significantly. Adequate Ca and P supplementation exerts a positive effect on the mineral composition of bones and whole antlers of farmed fallow deer fawns, and it enhances the concentrations of macroelements in tissues, which may constitute a reservoir used for future development of antlers. It also has a positive effect on body weight.

Effect of Ca and P supplementation on the haematological parameters and content of selected minerals in the blood of young farmed fallow deer males (Dama dama)

The aim of the study was to assess the effect of supplementation of feed rations with increased calcium and phosphorus doses on the haematological parameters and plasma zinc (Zn), phosphorus (P), magnesium (Mg), copper (Cu), calcium (Ca), and iron (Fe) content as well as the body weight and the growth and development of the first antler in farmed fallow deer (Dama dama Linnaeus, 1758). The mean level of erythrocytes (RBC), haemoglobin (HGB), and haematocrit (HCT) was increased in the Ca- and P-supplemented group after the treatment period. The change was statistically significant (p < 0.05) in the case of RBC and HCT. The other haematological parameters (mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), and platelet count (PLT)) were reduced. An increase in the Zn content was observed in the plasma of slaughtered animals. The concentration of other minerals (P, Mg, and Cu only in group II receiving a higher level of Ca and P in the feeding dose; Ca and Fe only in group I supplemented with a lower content of Ca and P in a nutritional dose) in blood plasma decreased slightly after the supplementation period and declined further after the slaughter. Noteworthy, there was a significant increase in the plasma Cu and Fe levels in group I in group II, respectively, in the post-supplementation period. No significant differences were observed in the body weight between the groups, but there was a beneficial effect of the higher Ca and P dose in the feed ration for the farmed fallow deer on the length of the first antler (p < 0.05). The antlers of animals in group II were on average 2.3 cm longer than in group I.

Nutrition of antler growth in deer

Stags are susceptible to the effects of nutrition at several stages during their lives and during the antler cycle. Nutrition during the in utero, post-natal (suckling) and yearling stages influences the size of spike antlers, and, generally, there is a close relationship between bodyweight and antler weight in stags aged up to 5 years. While antler size is not greatly affected by nutrition during the growth of immature (velvet) antler, it is influenced by body size and condition at casting, i.e. at the beginning of new antler growth. Antler growth appears to have a high priority for nutrients, especially energy, protein and calcium. Antler growth in adult stags is little affected by diet protein concentrations over 7%, but supplements of protected protein or methionine may improve antler growth. Substantial amounts of calcium and phosphorus are sequestered in antlers as they become mineralised, and calcium is withdrawn from the skeleton in support of this. Feeding programs to obtain good antler growth involve recognising the periods when juvenile stags are susceptible to under-nutrition, and providing sufficient nutrients to re-establish adequate body condition in adult stags between the end of the rut and antler casting.

Element concentrations and element ratios in antler and pedicle bone of yearling red deer (Cervus elaphus) stags-a quantitative X-ray fluorescence study

The present study compared the concentrations of different elements (Ca, P, Mg, Sr, Ba, K, S, Zn, Mn) as well as Ca/P, Ca/Mg, Sr/Ca, and Ba/Ca ratios in hard antler and pedicle bone of yearling red deer stags (n = 11). Pedicles showed higher concentrations of calcium and phosphorus and a higher Ca/Mg ratio than antlers, while antlers exhibited higher concentrations of potassium, sulfur, and manganese as well as higher Ca/P, Sr/Ca, and Ba/Ca ratios. The findings indicate that antlers are less mineralized and show less maturation of their bone mineral than pedicles. Antlers also showed a higher intrasample variation of mineralization than pedicles, which can be related to the shorter life span of the (deciduous) antlers compared to the (permanent) pedicles. It is suggested that antler bone formation is stopped before the theoretically possible degree of mineralization and mineral maturation is reached, resulting in antler biomechanical properties (high bending strength and work to fracture) that are well suited for their role in intraspecific fighting. It is further suggested that the differences in Sr/Ca and Ba/Ca ratios of antlers and pedicles are related to the dietary shift from milk to vegetation in combination with an increasing intestinal discrimination against Sr and Ba with age, resulting in a less marked difference in these ratios than would be expected based on the dietary shift alone. The findings of our study underscore the suitability of antlers and pedicles as models of bone mineralization and the influence of different animal-related and/or external factors on this process.

Effects of feed supplementation on mineral composition, mechanical properties and structure in femurs of Iberian red deer hinds (Cervus elaphus hispanicus)

Few studies in wild animals have assessed changes in mineral profile in long bones and their implications for mechanical properties. We examined the effect of two diets differing in mineral content on the composition and mechanical properties of femora from two groups each with 13 free-ranging red deer hinds. Contents of Ca, P, Mg, K, Na, S, Cu, Fe, Mn, Se, Zn, B and Sr, Young's modulus of elasticity (E), bending strength and work of fracture were assessed in the proximal part of the diaphysis (PD) and the mid-diaphysis (MD). Whole body measures were also recorded on the hinds. Compared to animals on control diets, those on supplemented diets increased live weight by 6.5 kg and their kidney fat index (KFI), but not carcass weight, body or organ size, femur size or cortical thickness. Supplemental feeding increased Mn content of bone by 23%, Cu by 9% and Zn by 6%. These differences showed a mean fourfold greater content of these minerals in supplemental diet, whereas femora did not reflect a 5.4 times greater content of major minerals (Na and P) in the diet. Lower content of B and Sr in supplemented diet also reduced femur B by 14% and Sr by 5%. There was a subtle effect of diet only on E and none on other mechanical properties. Thus, greater availability of microminerals but not major minerals in the diet is reflected in bone composition even before marked body effects, bone macro-structure or its mechanical properties are affected.

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.

Effects of ad libitum mineral consumption in Iberian red deer hinds and calves

Minerals are essential nutrients for ungulates because they cannot be synthesised. Lactation is the most mineral-demanding stage for hinds, whereas for calves both the pre- and post-weaning growth periods are important for bone formation, among other processes. Because both physiological effort and hot Mediterranean climate may increase mineral needs even in a situation under an ad libitum high plane of nutrition, we examined the effects of free-choice, single-mineral consumption in red deer hinds and their calves during lactation, and in the calves, from 18 to 56 weeks after lactation. Group M had permanent access to minerals, the control group had no access, whereas the LM and PLM groups of calves had access to minerals only during lactation or after lactation, respectively. Hinds with or without mineral supplements during lactation did not show differences in weight or body condition, neither did female calves of any group during or after lactation. However, after controlling the effect of year, LM male calves achieved greater weight gains during the post-lactation experiment, whereas the PLM and M groups showed negative results in weight at the end of the post-lactation experiment and age of antler growth initiation, respectively. The LM group also achieved higher scores in all the studied first antler variables (length, weight, burr perimeter, and perimeter in the middle of the antler) after controlling the effects of weight and year. The results thus suggest that, under ad libitum access to high-quality food, mineral supplementation is only positive during lactation. However, it cannot be ruled out that minerals may be beneficial in other stages in free-ranging deer.