Welfare issues of modern deer farming

The good, the bad, the comfortable: a review of welfare practices and indicators based on the five domains model in farmed deer

Increasing consumer interest in game meat has globally expanded wild animal farming, with deer being a prominent non-traditional species farmed in numerous countries. Consequently, methods for assessing the welfare of captive animals have been developed over the last few decades, and despite its limitations, the Five Domains Model has become one of the most popular practical tools for welfare assessment. Our review focuses on welfare indicators in farmed red and fallow deer, the primary deer species in European farms. Among 57 studies, the majority emphasized deer health and nutrition, neglecting aspects like behavior and mental state. Notably, a significant portion explored human-animal interactions, especially in deer transportation. Summarizing literature for each domain, we propose reliable physical, behavioral, and physiological welfare indicators for farmed red and fallow deer. This comprehensive approach addresses current research gaps and contributes to enhancing the overall well-being of farmed deer.

Concentration of Potentially Toxic Elements in Farmed Fallow Deer Antlers Depending on Diet and Age

Deer antlers, usually harvested annually on a farm, are an accessible material used to determine the exposition to potentially toxic elements, PTEs, during growth. Moreover, the study of antlers from animals of different ages allows the assessment of long-term exposition to these elements. The aim of the study was to analyze the concentration of eight potentially toxic elements (Cd, Pb, As, Ba, Ni, Sr, La, Ce) in individual positions of the antlers (first, second, and third position, corresponding to the stages of development and life of these animals) and in the food that the animals consumed during the growth of individual antler fragments, depending on the age of the farmed fallow deer (Dama dama). The mineral composition of samples was analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The analysis included 31 male deer aged 2-8 years old. The average concentration of Pb, Ba, and Ni was higher in the second position of the antler, and As, La, and Ce in the third position. In addition, the oldest individuals showed a higher Cd, Pb, and As concentration in the third position. A significant positive relationship was found between the age of animals and accumulation of As (r = 0.582, p < 0.05), as well as Ba and Sr (r = -0.534, r = -0.644 at p < 0.05, respectively). The average content of Ba and Sr also significantly negatively depended on body mass and antler mass stags (r = -0.436, r = -0.515 at p < 0.05, respectively). Cd concentration in feed was significantly higher in June compared to winter, spring, and later summer (p < 0.05). On the other hand, the concentration of Ba in food was significantly higher in spring and winter than in early and later summer (p < 0.05). An increase in the PTEs in the pasture determined the concentration of these components in fallow deer antlers.

A Protocol to Assess the Welfare of Patagonian Huemul (Hippocamelus bisulcus) in Conservation Centers

Animal-welfare-assessment protocols are important for identifying welfare problems in conservation programs. This study aimed to develop a baseline welfare protocol for the assessment of the welfare of Patagonian huemuls (Hippocamelus bisulcus) in conservation centers. This protocol is based on the Welfare Quality® (WQ) framework for cattle and was developed with the consideration of the available research on the behaviors, ecology, conservation, and captive management of this species, as well as welfare-assessment protocols for other ungulate species. As a result, the protocol was specifically developed for Patagonian huemuls and included four principles, 12 criteria, and 23 animal- and resource-based indicators. The twelve criteria of the WQ protocol were reduced to nine, and three new criteria were added because they were both feasible and essential for welfare assessment in captive Patagonian huemuls. This protocol is mainly intended to identify welfare problems in endangered species in the context of conservation centers (reproduction, rescue, rehabilitation, or treatment centers). Thus, the aggregation of different measures to obtain a global score was not proposed. However, a scoring system that assigns a value on a 0-2 scale (0 = no welfare concern; 1 = welfare concern; 2 = urgent welfare concern) was proposed for each category. Although further research is still needed to fully validate the protocol, this is the first development of a protocol to assess Patagonian huemul welfare, and it can be used as a basis for the development of welfare-assessment protocols for other deer species in captivity.

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.

Composition of Fatty Acids in Bone Marrow of Red Deer from Various Ecosystems and Different Categories

In this study, the influence of the living conditions of red deer (Cervus elaphus) fawns (wild vs. farmed) and effect of the category of free-living animals (fawns vs. does) on the fatty acid (FA) profile of the leg bone marrow was assessed. The composition of FAs in the deer bone marrow was determined by the gas chromatography method. In all groups, oleic acid (18:1 c9) was the most abundant in deer bone marrow and comprised of approximately 37% of total FAs. The bone marrow of young wild deer was characterized by a significantly (p < 0.001) higher fat content and saturated FAs proportion, while farmed fawns contained more moisture (p < 0.005) and fat-free dry matter (p < 0.001), as well as more monounsaturated FAs cis branched-chain FAs and monounsaturated FAs trans (p < 0.001). Although no significant (p > 0.05) differences were found between fawns, in terms of partial sums of PUFA, a significantly (p < 0.001) higher level of the sum of n-3 and n-6 FAs and more favorable n-6/n-3 ratio in the bone marrow of wild fawns were determined. In general, the legs of wild fawns were better prepared for wintering than farmed ones. In turn, comparing the category-related FAs composition in the bone marrow of free-living animals, a more favorable profile was observed in the adult (does) than in the young (fawns) animals, as the bone marrow of the wild does was characterized by significantly (p < 0.001) lower percentages of saturated FAs and a higher percentage of monounsaturated FAs cis.

Composition and Fatty Acid Profile of Bone Marrow in Farmed Fallow Deer (Dama dama) Depending on Diet

There are few studies on the composition of fatty acids and how they change the bone marrow fat of young animals depending on nutrition. Therefore, the proximate and fatty acid composition of metatarsal bone marrow from fawns of farm fallow deer after a summer of grazing and the winter feeding was compared. Due to the size and nature of the data, parametric or nonparametric tests were used. Fatty acid composition was determined by gas chromatographic analysis. After the winter feeding, bone marrow contained more fat (83.11% vs. 75.09%, p < 0.05) and less fat free dry matter (5.61% vs. 13.76%, p < 0.05) compared to the pasture period. Moreover, there was a significantly higher amount of saturated fatty acids (23.34% vs. 21.60%, p < 0.001), more trans fatty acids (2.99% vs. 2.34%, p < 0.005), and conjugated linoleic acid isomers (1.04% vs. 0.83%, p < 0.01), compared to post winter feeding, which in turn contained significantly more total cis-monounsaturated fatty acids (54.65% vs. 58.90%, p < 0.001). The percentage of polyunsaturated fatty acids (including n-3 and n-6) was not affected by feeding season. In conclusion, it was shown that young male farm fallow deer were better nourished after the winter period, during which they were kept in properly prepared rooms and fed fodder prepared by people.

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.

Accumulation of Toxic Elements in Bone and Bone Marrow of Deer Living in Various Ecosystems. A Case Study of Farmed and Wild-Living Deer

The aim of the study was to determine the concentrations of toxic elements accumulated in the bone marrow and bones (Cervus elaphus). The studies were carried out on two groups of young stags: farmed (n = 6) and wild (n = 9). Their body weights were measured and bone and bone marrow samples were collected. The concentrations of toxic elements were analyzed using the inductively coupled plasma mass spectrometry technique. The mean aluminum content in the bone marrow and bones of the farmed animals was significantly higher than in the wild group (p < 0.05). The mean concentration of arsenic, barium and lead in the bones of the wild red deer was significantly higher than in the bones of the farmed animals (p < 0.05), while the cadmium concentration in the bones of the farmed red deer exceeded the value determined in the wild animals. A significant difference was found between the mean concentrations of aluminum, arsenic, barium, lead, vanadium and nickel in the bone marrow and bones of both red deer groups (p < 0.05). Although the study involved animals living in an uncontaminated area, the concentrations of some heavy metals were higher than values reported from industrial regions.

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.

The effect of high ultimate pH on the quality of three muscles from farm-raised fallow deer (Dama dama)

Muscles (m. supraspinatus, SP; m. longissimus thoracis et lumborum, LTL; m. semimembranosus, SM) of 16 farm-raised fallow deer were analysed to study the effect of normal and high pH on the quality of venison. While 60% of analysed SP muscles were characterised with an ultimate pH (pHu) of ≥6.0, the pHu of LTL and SM was of a normal level (pH ≤ 6.0) for most of the analysed fallow deer. The SP with a normal and high pH had the highest pHu among the analysed muscles (P = 0.009). High pHu resulted in redder meat (P = 0.004). LTL and SM with a high pHu were characterised with the lowest value of H° (P = 0.006). The drip loss and the percentage of total water were higher for SP than for the other analysed muscles (P = 0.001 and P &lt; 0.0001). The free water and the free-water share in total water were most affected by the pHu (P = 0.001) among the analysed traits related to water-holding capacity of meat, and were lower for venison with a high pHu than for that with a normal pHu. The high-pHu venison was related to a lower cooking loss (P = 0.002) and a slightly higher meat plasticity (P = 0.027) than was the meat with a normal pHu. The proximal chemical composition of the fallow deer muscles was not influenced by the pHu (P = 0.817–0.983) nor by the carcass weight (P = 0.121–0.964). From the present results, it can be concluded that high-pH and normal-pH venison have different qualities. This also means different culinary and technological characteristics depending on the pHu value. The incidence of high pHu was the highest in the SP.