Body weight and morphological profile of blood of deer (Cervus elaphus) in the conditions of Polissia Volyn

The homeostasis of the whole organism and the analysis of hematological parameters in red deer (Cervus ela-phus) play an essential role in comparative physiology for health assessment and disease diagnosis. The obtained blood results can be the basis for assessing the condition of wild deer populations with an existing clinical picture or characterize the nutritional status, habitat, or other stress factors, as the hematopoietic system is susceptible to any changes in the animal body. In the course of the research, it was found that the body weight of adult deer varied depending on the population. Female deer of the Latvian and Lithuanian crossbreeds and the Eastern European population had the highest weight. As for the males, the animals of the Hungarian population had a higher weight than the English population. A high level of growth intensity in the early postnatal period was characteristic of both young females (body weight gain was in the range of 44.8–45.8 kg) and males (42.6–44.12 kg). The analysis of hematological parameters confirmed that the number of red blood cells and hemoglobin content increased in the blood of animals of the English population under technological stress (by 5.6 and 4.4 %). Regarding individual populations, it was noted that under the same conditions of immobilization of animals (medication), the number of red blood cells in the blood of Latvian crossbred deer was 8.5 % higher than the English population. The hemoglobin content was 5.3 % lower, and the saturation of red blood cells with hemoglobin was 12.9 % lower. It was found that the hematological parameters of 3–4 month-old fawns (females and males) of the English population were characterized by relative stability. Against the background of a tendency to a higher number of red blood cells in females (by 12.8 %), the hemoglobin content was 3.3 % lower than in males. The number of leukocytes in the blood of females was slightly higher than that of males, although no significant deviations were noted in some forms of white blood cells.


Introduction
The "Amila" farm is territorially located in the Western Polissia zone, in particular, in the Kovel district of the Volyn region.According to the economic and production characteristics, this is a multi-branch formation of the animal husbandry direction, in which the dairy industry and pig breeding prevail.Starting in 2017, another area of production activity, reindeer herding, was launched here.Moreover, for the first time in this region, breeding and growing of red deer (Cervus elaphus) is carried out both in semi-free conditions (enclosure, area of forest land over 2,000 hectares) and in the form of a typical modern farm (area of fenced enclosures for animals is 160 hectares).The acclimatization of the first deer (females and males) imported from Latvia, Lithuania, and the Republic of Poland, in moderate climate conditions and rich in diversity of forests and vegetation zone of Polissia, was successful.Today, there are more than 900 red deer on the farm.At the same time, it is essential to note that all conditions have been created here for the breeding of this species of wild animals in pure lines.Thus, three populations of deer (English, Hungarian, and Eastern European) and two crossbreeds (Latvian and Lithuanian) were brought to the farm.The created system of maintenance and registration of adult females and males (animals of each population, including males, are in separate pens) allows for obtaining young animals of the appropriate genetic line.The situation is somewhat different here regarding breeding red deer in the aviary's semi-free conditions.Interbreeding within one population is no longer possible.Animals aged 1.5-2 years from different breed groups with available chips are released into the enclosure's forest areas, where maintenance continues.
The system of raising red deer in farm conditions, which is aimed at obtaining a healthy herd of animals and valuable products from them (meat) and trophy qualities (horns, antlers), involves a whole complex of biotechnologies (creation of areas for feeding and supplementing animals, including part of mineral, organization of water supply, arrangement of covers), zootechnical and veterinary sanitary measures (chipping and weighing of animals, dehorning, etc.) (Kudrnáčová et al., 2018;Ghielmetti et al., 2021;Balińska & Demiaszkiewicz, 2022).Under certain conditions, the total or partial dispensation of deer is carried out on deer farms (Ievtushevskyi, 2012;Khoietskyi et al., 2014;Lyko et al., 2015;Volokh, 2015).It usually includes, in addition to an assessment of the general condition of the animal, determination of its body weight (at a particular stage of development), coprological examination of feces for the presence of eggs or larvae of helminths, and a selective examination of blood according to morphological and biochemical indicators.
The body weight of red deer, which is kept in the conditions of a farm or enclosure, has significant fluctuations and depends on its population, geographic location of the farm, conditions of keeping, feeding, and supplementary feeding of animals, age, sex, etc.It is believed that animals gain weight more intensively in the pasture period.In the winter, the intensity of metabolic processes in their bodies is low, so even a decrease in body weight is possible compared to other research periods.As for the males, their weight, according to many researchers, changes significantly during the rut period (in the conditions of Polissia -the end of August-October).According to some reports, the body weight loss during this period in males can be from 20 to 30 % (Vudmaska et al., 2016).According to the reports of many scientists who deeply specialize in studying the peculiarities of metabolic processes in the body of deer or research factors that have a decisive influence on the health of individual individuals of this species of wild animals, it is essential to monitor the morphological and biochemical indicators of blood.Evaluation of hematological indicators in deer plays an indispensable role in comparative physiology, as it makes it possible to compare the studied indicators of animals depending on their populations, age, sex, etc (Rauch et al., 2022;Kulka et al., 2022).
The blood system is one of the most mobile and reacts very quickly to changes in the body's homeostasis that may occur against the background of introduction or changes in forms of maintenance (Slobodian et al., 2019;Martyshuk et al., 2019;Varkholiak & Gutyj, 2020;Ligomina et al., 2023;Khalak & Gutyj, 2023).Hematological analysis is one of the standard tests to confirm the animal's health status through laboratory research (Kulyaba et al., 2019;Borshch et al., 2020;Grymak et al., 2020).Publications in the scientific literature indicate that the hematological and biochemical parameters of red deer blood also have wide fluctuations (Gubta et al., 2007;Poljicak-Milas et al., 2009;Rafaj et al., 2011).Hematological indicators of deer have a correlative relationship with body weight.Animals with smaller body mass and size have proportionally higher metabolic rates than more significant and more massive animals.A higher metabolic rate leads to a greater demand for oxygen and, therefore, causes an increase in the total number of red blood cells and red blood cell hemoglobin and hemoglobin concentration (Rawson et al., 1992;Spaargaren, 1994).Geographical location, physical activity, age, breed, sex, signs of disease, stress, etc., can also affect indicators characterizing the state of wild animal populations (Rafaj et al., 2011;Vudmaska et al., 2016).
In addition, the method of immobilization (immobilization) of the animal is essential in the assessment of the studied indicators in the blood of deer (Topal et al., 2010;Munerato et al., 2010;Caulkett & Arnemo, 2014).At the same time, data on the reference constants of hematological and biochemical indicators of red deer are scarce, and those available differ significantly (Arnemo & Soli, 1993).Most of the described indicators were obtained from animals subjected to anesthesia or muscle relaxation with the help of tranquilizers.It is believed that the very procedure of blood sampling from deer under stress can significantly affect the results obtained (Cross et al., 1988).
This stage of the work's purpose was to determine the body weight and morphological indicators of red deer blood depending on the conditions of keeping, age, article, and type of population and according to different blood sampling methods.

Materials and methods
We collected and analyzed the results of weighing red deer females of different populations (n = 10) and males (n = 3) aged 2-3 years.In addition, the weight of young deer (age 3-4 months) was estimated.
Seven groups of deer (n = 10) were formed to select and study blood samples for the experimental part of the work.Groups R1-R3 -deer (females) of the English population, aged 2-3 years, kept in a herd (fenced area of 8 hectares, drinking water from automatic watering systems, existing feeding system, and a system for providing agrotechnical and veterinary measures).Animals of the first and second experimental groups (R1; R2) were subjected to prophylactic deworming with the drug Ivomec® (subcutaneously, 1 mL per animal).The deer of group R3 were not dewormed.Animals of groups R4 (English population) and R5 (Latvian crossbreed) were also 2-3 years old.Animal groups R6 (males) and R7 (females) are fawns of the English population, 3-4 months old, which were kept in pens with females (mothers) in fenced areas.
Considering the reports of several scientists (Cross et al., 1988;Topal et al., 2010;Bashchenko et al., 2021;2023) that the results of morphological and biochemical studies of blood differ significantly in animals with different immobilization methods, we used two methods of contact with deer during blood sampling.Thus, deer of the first and second experimental groups (R1, R2) and young animals (R6, R7) became the object of research after running them through the appropriate system of transition corridors and fixation in the machine (box).In the conditions of the "Amila" farm, wild animals of this species, as a rule, are driven twice a year through labyrinths to the central box for chipping, regrouping, separation of males from females, weighing, dehorning, veterinary preventive measures, in particular, deworming.In such cases, there is a real opportunity to take blood from deer for research.However, with this form of capture, wild animals are usually subjected to technological stress, which can impact the obtained results.
The animals of the third, fourth, and fifth experimental groups (R3, R4, R5) were subjected to the drug immobilization method.To create the effect of sedation and muscle relaxation and 30-minute immobilization of deer, we used the xylazine-containing drug "Ksyla" (Interchemi verken "De Adelaar" Esti AS, Estonia).It was administered to animals using an exceptional DAN inject gun at a dose of 1 ml per 100 kg of body weight.The time from the administration of the drug to the start of blood sampling was 30-45 minutes.
Blood for research was taken from deer by puncture from the jugular vein.In separate vacuum tubes, "Vacutest" was used with the help of a double-sided "Voles" needle (21G), and 8-9 ml of blood was taken for serum research (red lid, with activator).Blood was also taken into separate test tubes for the morphological study of whole blood (lilaccolored lid, EDTA) and its plasma (green-colored lid, heparin).At the same time, blood samples were centrifuged at 1500 rpm for 10 minutes to obtain plasma.Whole blood was stored in a refrigerator (+4 ºС), and hematological studies were performed within 24 hours.Blood smears were examined under a Leica D 500 light microscope.
Laboratory serum and blood plasma analysis were performed using the HumaLyzer 3000 analyzer and standard certified test kits "Human Diagnostics Worlwide" (Germany), and separate hematological studies were performed using the Mythik18Vet analyzer.

Results and discussion
It was found that the body weight of red deer varied and depended on their population, age, and sex (Table 1).At the same time, the weight of males in all studied populations was significantly higher than that of females.In particular, the most massive were males of the Eastern European breed.The difference between their weight and the weight of males of the English breed (which are the smallest) was, on average, 46.4 kg.Regarding females, the mass of females of the Latvian and Lithuanian crossbreeds and the Eastern European population was the highest.Meanwhile, the body weight of the females of the English and Hungarian populations, as well as the males, was relatively lower.At the same time, it should be noted that the weight of fawns born from females with lower body weight was also lower.
Regarding the intensity of metabolic processes, it is evident that they were sufficient in all groups of deer.This is confirmed by the fact that the body weight of males and females of the English and Hungarian populations at 3-4 months was at the average similar indicators of males and females born with a more significant weight.It should also be noted that significant differences in the animals' body weight could result from different ages (3-4 years, 3-4 months).Unfortunately, achieving an unambiguous selection of analog animals in reindeer husbandry is challenging.Therefore, as a result of the conducted analysis, we are talk-ing only about the revealed regularity in the dynamics of the body weight of animals in specific periods of research.
Morphological and biochemical indicators of blood can be the basis for assessing the state of health of deer in wild populations with or without a clinical picture, as well as characterize the supply of animals with nutrients and mineral substances or be a reaction to stress factors (Knox et al., 1988;Pareja-Carrera et al., 2018;Mylostyvyi et al., 2021;2024).Functionally, the hematopoietic system is sensitive to changes in the body, especially stress.
In this article, only hematological status is presented and discussed.The evaluation of the obtained biochemical indicators will be published later.By studying hematological indicators in red deer, we confirmed the results of the research of many scientists that these indicators are significantly subject to fluctuations due to the peculiarities of taking blood samples from animals (Table 2).Stressful factors usually disrupt the established homeostasis in animals and provoke numerous disorders, in particular, the slowing of growth rates against the background of metabolic disorders, a decrease in the reproductive capacity of animals, and an increase in their susceptibility to diseases due to a reduction in immunity (Pareja-Carrera et al., 2018).-0.9-1.2 1.14 ± 0.09 1.02 ± 0.07 1.10 ± 0.02 Note: in this and the following tables: * -Р < 0.05; ** -Р < 0.01; *** -Р < 0.001 Thus, it was established that against the background of a stressful factor (running to a stationary box) in the blood of red deer of the first experimental group (R1), compared to the indicators of animals (R2) immobilized with a xylazinecontaining preparation, the number of erythrocytes, hemoglobin content, and hematocrit increase by 5, 6, 4.4 and 10.5 %, respectively.At the same time, the obtained results, particularly regarding the number of erythrocytes in the blood and the hemoglobin content, were within the limit values.At the same time, the hematocrit index was somewhat higher.
Based on the evaluation of blood indices, it was found that the average erythrocyte volume (MCV) and the average hemoglobin content in one erythrocyte (MCH) in the blood of animals of groups R1 and R3 did not differ significantly.Regarding the saturation of erythrocytes with hemoglobin (MCHC), it has been confirmed that in deer groups R1 and R3 under stress, in our case most likely technological, the increase in the concentration of hemoglobin in one erythrocyte (MCHC) is a compensatory reaction.Against the background of a tendency increase in the blood of deer of group R1 compared to R3 in the number of leukocytes (by 28.8 %), based on the evaluation of the leukogram, we noted a probable (P < 0.01) increase in the percentage of segmented neutrophils and a pronounced tendency to increase in the blood of animals of this group number of lymphocytes (Table 3).Our blood test results are comparable to the hematological indicators in deer obtained by other researchers.Thus, Gross et al. (1988) claim that in animals subjected to capture by physical means, in contrast to deer that were immobilized with xylazine, higher numbers of erythrocytes, leukocytes, platelets, and hemoglobin content were recorded in the blood (Cross et al., 1988).
The significant differences between the hematological indicators of deer with different methods of capture (physical and chemical) are evident because the spleen shrinks during the period of stress (physical capture) and releases a significant amount of catecholamines during this period, which can contribute to the growth the number of red blood cells in the blood even up to 40 %.The latter, in addition, can cause transient leukocytosis with an increased content of neutrophils, monocytes, and lymphocytes (Marco & Lavin, 1999;Rafaj et al., 2018).
In this series of experiments, we also analyzed hematological indicators in deer against the background of preventive deworming.According to the results of the spring (2021) parasitological survey of red deer of various ecotypes, we found in the feces of animals, for the most part, eggs of strongylate infestations of the alimentary canal (Trichostrongylus axei, Ostertagia ostertagia, Cooperia ancophora, Chabertia ovina) and larvae of strongylate infestations of the respiratory tract (Muellerius capillaris), which are typical of other ungulate species (Hunchak et al., 2022;Hunchak & Yuskiv, 2023).According to the scheme of the experiment, red deer of the R1 group were treated with an anthelmintic agent, while those of the R3 group were not.The method of capturing animals to take blood samples was the same here -they were driven to a stationary box, and biomaterial was obtained for fixation.As a result of the research (Table 2), it was established that in non-dewormed deer of group R3, against the background of the chronic development of the pathological process caused by hel-minths, the number of erythrocytes in the blood decreased (by 10.1 %) (Р < 0.05) and hemoglobin content (by 7.3 %).However, the level of platelets in the blood of animals not treated with an anthelmintic (R3) was higher than the level of animals of group R1 by 7.8 % (Р < 0.01).The obtained results are most likely the result of the toxic effect of helminths and their decay products on the hematopoietic system of the deer's body.This is confirmed by a probable (P < 0.01) increase in the number of leukocytes in the blood by 23.7 %, the percentage of eosinophils (more than three times), and a halving of lymphocytes.
The next series of experiments was devoted to determining morphological indicators in the blood of deer from different populations (Tables 4 and 5).
We have established that the investigated blood indicators of clinically healthy (according to the assessment of the general condition of the animals) deer of different populations, although unlikely, differ somewhat.Thus, during the chemical immobilization of animals of both research groups, the number of erythrocytes in the blood of deer of the Latvian crossbreed was higher by 8.5 % compared to the similar indicator of animals of the English population.Against the background of a decrease in the hemoglobin content (by 5.3 %), it is natural that both the average hemoglobin content in erythrocytes (MCH) and the saturation of the latter with hemoglobin (MCHC) in the blood of deer of the R5 group were somewhat lower.No significant differences were found in the analysis of the leukogram in the blood of deer of the English population and the Latvian crossbreed (Table 5).The existing tendency to increase the number of leukocytes in the blood of adult female deer of the R5 group was created, apparently, due to the increase in the percentage of rod-and segmentonuclear neutrophils, compared to animals of the R4 group, against the background of a slight tendency to decrease the rate of lymphocytes.There are few reports on the morphological composition of deer blood depending on the population.The results of hematological studies of wild animals of the English population and the Latvian crossbreed were within the reference values, although they tended to differ somewhat.It is necessary to consider that the body weight of the animals of these groups was also different (Latvian crossbreed females, approximately the same age, prevailed in the body weight of the English fawns by 16 kg or 15.9 %).Given certain features of the course of metabolic processes, a somewhat different genetic potential is a determining factor in the stability of homeostasis in animals of various origins.
So, as a conclusion, we can state that hematopoiesis in deer, as representatives of wild fauna, is characterized by a relatively stable number of erythrocytes and leukocytes in the blood, and the hemoglobin content provides animals of different populations with a sufficient level of oxygenation of metabolic processes and other vital processes in their bodies.
We also discovered certain features of hematopoiesis in young deer.It was established that hematological indicators in 3-4 months.The English population's fawns (females and males) were characterized by relative stability (Table 6).According to the results of the study, it was established that there is a probable difference in hematological indicators, in particular in the number of erythrocytes and the hemoglobin content in the blood at 3-4 months.There are no females or males in the English population.However, it was noted that, against the background of a tendency for a higher number of erythrocytes in females (group R7, by 12.8 %), the hemoglobin content was 3.3 % lower than in males of group R6.It is natural that with such a ratio of the number of erythrocytes and the hemoglobin content in the blood, the saturation of erythrocytes with hemoglobin in the group of females (R7) was at the level of 25.7 mmol/L, and in males of the group R6 -29.1 mmol/L.
The color index, hematocrit value, and the number of platelets characterized the blood of young deer, in terms of sex, as relatively stable values that did not exceed the limits typical for animals of these age groups, even by digital measurement.
Despite a tendency for a more significant number of leukocytes in the blood of females (by 21.9 %, group R7), the percentage of individual forms of white blood cells was similar to that of young males (group R6) and within the reference values.

Conclusions
1.The body weight of female deer of the studied populations was between 96.6 and 112.2 kg, and that of males was between 190.0 and 236.4 kg.The most significant body weight was found in female deer of the noble Latvian crossbreed and the smallest -of the English population.Regarding males, the difference between the most extensive body weight (Eastern European population) and the smallest (English population) was 46.4 kg.
2. Young females typically experience a high level of growth intensity in the early postnatal period (body weight gain was 44.8-45.8kg), and males' gain was slightly lower -42.6-44.2kg.
3. It was established that against the background of technological stress (taking blood from animals after running them through a system of labyrinths), the number of erythrocytes and hemoglobin content in the blood of deer increases by 5.6 and 4.4 %, respectively, compared to deer immobilized by a medical method.
4. According to the analysis of blood taken from deer under medical immobilization, it was found that the number of erythrocytes in the blood of Latvian crossbreed animals was higher by 8.5 % compared to the rate of animals of the English population.At the same time, hemoglobin content (by 5.3 %) and saturation of erythrocytes with hemoglobin (by 12.9 %) were lower.
5. Against a relatively stable blood composition in young deer of the English population, a tendency to a more significant number of erythrocytes (by 12.8 %) and leukocytes (by 21.9 %) was noted in the blood of females.

Table 1
Body weight of red deer (Cervus elaphus) depending by population, age and sex, kg

Table 2
Blood morphological profile of deer in the English population by different methods of immobilization (M ± m, n = 10)

Table 3
Blood leukogram of deer in the English population depending on the method of animal immobilization (M ± m, n = 5)

Table 4
Morphological blood profile of red deer of English population and Latvian crossbreed (M ± m, n = 5)

Table 5
Blood leukogram of red deer depending on the population (M ± m, n = 5)

Table 6
Hematological indicators in young deer of the English population (M ± m, n = 5)