RADIATING PATHOLOGY IN AGRICULTURAL ANIMALS WITH A DISEASED THYROID GLAND

. Radioactive iodine is present in atmospheric fallout during the first hours of accidental emissions at nuclear power plants. It causes damage to the thyroid gland of varying severity. As a result of lesions with radioactive iodine, pathological changes develop in the thyroid gland, which can affect the productive indicators and reproduction of farm animals. Physiological changes are also diagnosed in animals that do not receive a sufficient amount of iodine compound with food or water. This can lead to pathology of the thyroid gland. Studies of the pathology of the thyroid gland should be carried out on the basis of structural modeling methods and data obtained experimentally. Analysis of the comparison of pathological effects allows to systematize information and use it in scientific and practical purposes. Depending on the intensity and duration of external and internal radiation exposure in farm animals acute or chronic radiation diseases can be diagnosed. Farm animals with or without signs of radiation disease of mild severity are left in farms and used for its intended purpose. Long-term effects of radiation can be manifested as temporary or permanent sterility, metabolic and endocrine status disorders, immuno-deficiency, increased sensitivity to infectious diseases, the emergence of tumors. Monitoring of the radio-logical situation on the territory of the livestock complex is of particular importance, as its products are transported to different regions. Livestock products must meet regulatory requirements. Timely and full implementation of general and specific rules in the field of radiation safety is aimed at ensuring the safety of animals and preserving the quality of animal products.


INTRODUCTION
In 1986, as a result of the Chernobyl accident, a significant part of Belarus, Ukraine and part of the Russian Federation were affected by radionuclide contamination. The problem of radiation exposure to farm animals was studied before the Chernobyl accident, thus a large experimental material was already collected, which allowed to diagnose radiation pathology of the thyroid gland of different severity [1][2][3][4]. Scientific fundamentals of diagnosis, methods of maintenance and therapy were in demand after the Chernobyl accident [3,[5][6][7][8][9].

MATERIALS AND METHODS
The aim of the study was to systematize the data of radiobiological studies obtained as a result of irradiation of sheep and physiological parameters in cattle, which were in the area of radioactive contamination and evaluate the productivity of irradiated animals.

Methods of logic and information modeling.
Using the methods of system analysis and modeling, the radiobiological parameters of cattle located on the territory of livestock complexes in the Gomel region were studied.

RESULTS AND DISCUSSION
Radioactive Iodine is present in atmospheric deposition in the first hours of accidental emissions at nuclear power plants. It causes thyroid lesions of varying severity. The thyroid gland is a part of the neuro-hormonal regulation system. As a result of radioactive iodine damage, pathological changes develop in the thyroid gland, which can be manifested as a result of direct irradiation of the exocrineepithelium and mediated -through the hypothalamic-pituitary system. The damage of the thyroid gland causes a violation in the functional activity in other parts of the neuro-endocrine system. The changes have a phase character and are manifested as a compensatory-adaptive response to hormonal disorders because of radiation exposure. Changes in the metabolic activity of the thyroid gland are also diagnosed in farm animals kept in areas with low concentrations of stable iodine in soil and feed. Iodine pathology is diagnosed on the physiological level in affected animals ( Fig. 1, Fig. 2). Endemic diseases of the thyroid gland are typical for Belarus. After the Chernobyl accident, it was necessary to determine what pathology of the thyroid gland and what methods of therapy should be used. On the basis of the designed structural and model schemes, information can be not only systematized, but also the cause of pathology can be modeled and identified ( Fig. 1, Fig. 2).

Results of studies of animals with affected thyroid gland
Chronic radiation disease, which is diagnosed in sheep with Iodine-131, develops slowly, early diagnosis of severity is difficult. When feeding with contaminated feed radiation pathologycan is diagnosed in sheep, for example: -if there is Iodine-131 microcurie 2.0 and above in a feed of the daily diet of adult sheep; -in the first 10 days of feeding bymore than 500 microcurie contaminated feed. In farm animals diagnosed symptoms of general lethargy, increased intestinal motility, severe diarrhea. The decrease in appetite is observed in the first 5-15 days from the beginning of feeding with contaminated feed, and there is a significant decrease in body weight after 15-30 days. Subsequently, leuko-, lympho-and erythropenia is diagnosed.
Experimental studies on the kinetics of Iodine-131 in the thyroid gland were carried out in ARRVI, Kazan (Fig. 3) [1]. The kinetics of Iodine-131 in sheep in the critical organ depended on the dose and multiplicity of seeding. As a result of the conducted experiments, the dependence of the thyroid activity index on the effective dose was found and the peculiarities of their dynamics were determined (Table. 1, Table 2, Fig. 3). As a result, on the basis of experimental studies, changes in the functional activity of the thyroid gland in time for all acting doses were established. The optimal absorbed dose, causing thyroid tumor in experimental animals is 2.3…16.0 krad; minimum -0.2 krad. During starvation in experimental animals there is a decrease in the activity of the thyroid gland. The dynamics of combined effect is similar to the dynamics during starvation. In calf-bearing cows, there is an increase in thyroid activity at the current dose of 45 microcurie\kg\days' 30 for the entire duration of the study, which corresponds to chronic radiation disease of II severity. Reduced activity is diagnosed at a dose of 600 rad + 1 microcurie\kg\once a day for adults + 7 days of srarvation, while developing an extremely severe degree of acute radiation disease for the period from 2 days to 15 days. Increases in activity of 15 days is noted with I degree of chronic radiation illness in influencing the dose of 4.5 microcurie\kg\day' 30. For the rest of the treatment doses that cause radiation disease is characterized by reduction in activity.  Conclusion: there are temporal dynamics of the activity changes at all dose levels; fasting -lowering activity (decrease in metabolism).

Experimental method in vitro
Designations: 1/F index reflecting the activity of the thyroid gland, the more 1/F, the higher the activity. ←decreasing trend from normal (control) N; → -increase Table 2 The absorbed thyroid dose β , γ radiation of Iodine 131 at 30 day introduction of isotopes of the sheep in the experiment

Metabolic features
The decrease in thyroid activity is recorded for high doses and in chronic radiation disease of II and III severity [6,7,9,10]. Features of the functional activity of the thyroid gland depend on severity of radiation disease.
1. Chronic radiation disease of I degree of severity is characterized by increased activity of the gland in lambs and sheep. After 1.5-2 months young indicators of thyroid activity in the contaminated farms are above the control. After 2 years, there was a decrease, and then again an increase in activity.
2. Chronic radiation disease of the II degree of severity: there was instability of activity in the first 2 months, depression with increased activity in the next 7 months and a sharp decline after 1.5 years.
3. Chronic radiation disease of the II degree of severity: a decrease in activity below control until the end of life.
It was determined that small doses cause increased activity, and large -inhibition of activity and destruction of organ parenchyma. On the basis of experimental data, it was found that at high acting doses, a decrease in the sensitivity of the nervous system is characteristic, which is diagnosed as an extension of the latent reflex time. At the same time, there is a decrease in productive indicators (Table 3). Table 3 Indicators of biological effectiveness of Iodine 131 in a dose dependent manner The dose of iodine 131 The radiation disease Absorbed thyroid gland dose (rad) Radiation has a direct and indirect effect on the activity of the nervous system and the processes of regulation. The experiments on sheep determined [1]: 1) chronic radiation disease of I degree of severity: 1.5 months after seeding, there is a significant acceleration of defensive unconditional reflex reaction; 2) acute radiation disease of moderate severity: unreliable acceleration of defensive unconditional reflex reaction; 3) with all other degrees of severity of acute and chronic radiation disease, there is a slowdown in the unconditional reflex reaction. The depth and severity of violations directly depends on the dose. With relatively small doses, an increase in the sensitivity of the nervous system is recorded. In the studied animals there are no changes in the productive indicators.
The diagnosed features of hormonal dynamics in cows with radiation damage of thyroid Iodine-131 may be associated with changes in other physiological systems [9]: 1) hematological parameters: no profound changes. In the radiosensitive system of erythroid hematopoiesis, a decrease in the number of erythrocytes is diagnosed and their dose dependence in individual individuals is weakly expressed; 2) the system of hemostasis: activation of coagulation secondary link and the primary inhibition of vascular-platelet link; 3) changes in the level of cyclic nucleotides in blood plasma: more pronounced in the spring and less pronounced in healthy cows in the "clean" area, systematically receiving alcohol-containing feed; 4) hormonal parameters: decrease in the level of T4 and T3 and disturbances in interhormonal relationships, as well as seasonal variability and a significant increase in the content of biologically active free fraction of cortisol due to a decrease in the binding capacity of blood proteins. The dose direct dependence of changes in the level of T4, T3, insulin and cortisol is determined, the dependence is direct -the higher the dose, the greater the change; 5) Changes in the hormonal status of cows with radiation damage to the thyroid gland cause disorders in the reproductive system (Table 5). In the first group of cows that received a large dose to the thyroid gland in the polluted farms of the Gomel region there is a decrease in reproductive capacity: a) reduced the index of impregnation capacity (in 1987), b) reduction of service period duration. For example, the duration of the service period by day in 1987 increases, and by 1989 in the studied farms decreases, i.e. shortens.

Reproductive performance
The account of reproductive indicators for farm animals is very important for any animal husbandry, and for those who are in the pollution zone they are of particular importance. To calculate the index of reproduction (Iv) for one individual, the calculation of the average value for the lifetime of the individual can be used: where Fi -the offspring (lambs); Pj -the sheep that produces it's offspring.

Time component accounting
The time component is taken into account when studying the time dynamics of both individuals and individuals in the group. At the same time the season, exposure factors, physiological time, etc. can be seen. In the system information analysis time allows to systematize the information considering the time of the study or the time period of the diagnosed changes.

Time dynamics
The change of indicators in time reflects the time dependence of changes in the studied parameters on the physiological norm and characterizes the stage of development of pathology (Table 4).

Physiological indices in the exposed cows from contaminated farms
At the farm "Strelichevo" Hoyniksky district study of cows affected with thyroid revealed some peculiarities [9,10].
Indicators of immune status: -No significant differences in the level of infection were found.
-The concentration of lysozyme in the blood serum in the summer was below the control values.
In cows that received a dose of 27-29 krad, the concentration of lysozyme in serum decreased by 24%, and in those who received a lower dose (16-18 krad) by 35%an inverse dependence on the dose.
-Bactericidal activity of blood serum: in group I cows it was at a sufficiently low level (26.4 ± 5.6%) (< N), and in group II it was higher (> N).

ВЕТЕРИНАРНО-САНИТАРНАЯ ЭКСПЕРТИЗА
Studies of reproductive and productive indicators of irradiated animals have shown that the most pronounced changes in them are diagnosed in farm animals: -with a higher absorbed dose in the thyroid gland; -consuming contaminated feed; -located in an area with a higher density of pollution. Comparative analysis of productivity in the polluted farm "Vysokoborsky" in Vetkovsky district (the maximum degree of pollution) and the Collective Farm of First of May, Chechersky district, where the animals were fed for 3 years after the accidental release of contaminated feed above 1.0⋅10 -6 Curie\kg, showed that in the long term, 4 years after the accident, there is a restoration of reproductive function and reproductive performance in cows, including cows with signs of thyroid damage ( Table 5).

The calculation of the coefficients relative to the physiological norm
The conducted researches were based on comparison of the diagnosed sizes with sizes of physiological norm. The comparison analysis revealed a number of differences, which are reflected in Table 5. Table 5 The

degree of priority of the indicators (maximum of the diagnosed values in the group) of thyroid hormones on the physiological norms for the groups of cattle Hoyniksky district (2 nd degree of pollution)
Year Quarter Triiodothyronine (T3) (nmol\l)  I  2  3  1  2  2  1  6 + 5  IV  1  3  2  1  1  1  > N  > N  6 + 3  1989  I  1  3  2  2  3  1  N  N  6 + 6  1989  II  1  3  2 no data + 6 Conclusion: the spread of values from the norm. (3 (0) -the value was diagnosed, but it is 0) Offspring obtained from cows with radiation damage to the thyroid gland are diagnosed with abnormalities [9]: -1-2 calves monthly changes in coagulogram -hypercoagulability; -increase in the level of cyclic nucleotides by 1.9-1.5 times; -decrease in the level of red blood cells; -platelet content 2 times higher than the control; -bactericidal activity of serum in young animals obtained from cows of group Iat a high level (> N): bulls 50.0%; heifers 44.6%; calves 66.6%; -the dynamics of hormonal parameters does not indicate pathological changes; -the main causes of mortality of calves received from cows with signs of radiation damage to the thyroid gland (I, II groups): dyspepsia; bronchopneumonia. Calves of first generation (F1) 1989 year birth lagged behind in growth -bulls dwarfs, but in the future, they gained height and weight, reaching a weight of 400 kg. Cows were resulting offspring in 1990. Calves born in 1990 (F2) from cows born in 1987 did not differ in their physiological development from young control and non-polluted farms, dominated by heifer. 30% of all livestock received in 1989-1990 were bull-calves; -hormonal parameters in offspring obtained from cows with varying degrees of radiation damage to the thyroid gland, deviate from the norm. Steers were characterized by the excess rates of T3 and T4 in the first quarter of 1989.Heifers had a decrease below normal in the second quarter of 1987 and in the first quarter of 1989 because of incomplete data and the lack of a temporal chronology of diagnosis, based on their changes obtained from the cows and the dose can not be determined.
Studies of the temporal annual variability of the average indicators of triiodothyronine and thyroxine indicate deviations from the norm. In cows of I group, for example, in 1987, in the period from the II quarter to IV, an increase in triiodothyronine was diagnosed, but below the norm (<N). At the same time, the minimum values of deviation from the norm, as well as the detected elevated triiodothyronine values fall above the norm. For thyroxine in the same period, the maximum values (average for the group) are observed for the group -more than the norm (>N), and the minimum valuesnorms (N).
The results of statistical studies revealed deviations from the physiological norm of hematological parameters in heifers (born in 1987) from the I group of cows with affected thyroid farm «Strelichevo» of Hoyniksky district (2 nd degree of pollution) [7,8]. Deviations were determined in the autumn.
The results of the diagnosis of biochemical blood parameters indicate their deviations from the physiological norm in the offspring obtained from cows with irradiated thyroid gland. In General, according to the diagnosed indicators in the offspring obtained from the I group of cows, it is noted: -for bulls born in 1986 had a decrease relative to the norm; -for calves -a small prevalence above the norm, but there is a decrease relative to the norm.
For groups of cows (I and II group) in total, there is a more pronounced decrease in biochemical parameters in the group that received a large dose to the thyroid gland. Biochemical indicators can be informative at radiation pathology, therefore it is necessary to carry out their diagnostics systematically on different age groups of farm animals, in comparison of producers and their posterity.
A comparative analysis of productivity in the polluted state farm "Vysokoborsky" of Vvetkovsky district (the highest degree of pollution) and on the Collective Farm of First of May of Chechersk district, where animals were fed for 3 years after the accidental emissions by contaminated feed above 1.0⋅10 -6 curie\kg, showed that in the long term, 4 years after the accident, there is a positive trend towards the restoration of reproductive function and reproductive performance in cows with signs of thyroid damage.

CONCLUSIONS
To assess the state of the endocrine system of farm animals located in the contaminated area, it is necessary to consider seasonal and age-specific dynamics of hormonal parameters by age groups and acting doses. Changes in endocrine parameters entail changes in other physiological parameters. For livestock management in contaminated areas, it is important to know how these changes will affect the reproductive and productive features of farm animals.
The most pronounced pathological changes after the Chernobyl accident were diagnosed in farm animals left in polluted farms. They were also diagnosed in cows with an affected thyroid gland. In offspring obtained from cows with the highest dose of thyroid radiation, deviations from the physiological norm were most pronounced in the first generation, and in the second generation of pathology was not noted.
When exposed to radioactive Iodine, thyroid damage is diagnosed, which is the greater the dose absorbed by the gland. It was determined that there are more pronounced the pathology of the thyroid gland, more pronounced the changes in physiological parameters and decrease of reproduction and productivity in farm animals.
Studies of reproductive qualities and productive indicators of irradiated animals showed that the most pronounced changes were diagnosed in farm animals that were on the territory with a higher density of pollution and with a higher absorbed dose in the thyroid gland.
It is advisable to carry out studies to identify changes in hematological, biochemical and hormonal parameters systematically in groups of farm animals, taking into account the radiation background of the area and livestock premises, the degree of contamination of feed. Comparative data analysis is necessary to identify dependencies and patterns. It should be carried out on different groups of farm animals exposed to different doses of radiation on the basis of methods of system analysis and modeling. The use of methods of system analysis and modeling allows not only to systematize the material of research and diagnosis, but also to predict the situation in the livestock complex. Радиоактивный йод присутствует в атмосферных выпадениях в первые часы аварийных выбросов на АЭС. Он вызывает поражения щитовидной железы различной степени тяжести. В результате поражения радиоактивным йодом в щитовидной железе развиваются патологические изменения, которые могут влиять на продуктивные показатели и воспроизводство сельскохозяйственных животных. Физиологические изменения диагностируют и у животных, которые не получают в достаточном количестве соединения йода с кормом или водой. Это может привести к патологии щитовидной железы.