ETIOLOGY OF HYPOTHYROIDISM IN CATTLE FROM ROSTOV REGION
Thyroid pathology is quite widespread in the territory of the Russian Federation and has a direct relationship with the imbalance of chemical elements in the environment. In particular, disorders are associated with a lack of iodine, which contributes to the development of hypothyroidism in cattle. In order to find out the cause of thyroid pathology, biogeochemical features of iodine and other micro- and macroelements, anthropogenic and technogenic contamination of the atmosphere and environment of the Rostov region were studied based on the analysis of the ecological and sanitary conditions in 43 districts. According to the conducted analytical studies, the iodine content in the soil of the Rostov region was found in the range of 0,0124-0,0934 mg/kg. The iodine content in the water ranged within 0,01 mg/dm3. The study of forage crops showed that the iodine content is 4-12 times lower in relation to the normative data. It is also found that fodder crops of the analyzed region in insufficient quantity contain such elements as copper, cobalt, manganese, zinc. Accordingly, when standard indicators of copper is 1-3 mg/kg, its amount is 0,6 mg/kg, cobalt standard indicators - 2,6 mg/kg, its amount is 3,0 mg/kg, manganese standard indicators - 12 mg/kg, its amount is 10 mg/kg, zinc standard indicators - 20-60 mg/kg, its amount is 15 mg/kg. Thus, these indicators define Rostov region as an area of secondary relative iodine deficiency. There is an increased heavy metal content in feed: nickel (1,25 mg/kg; at a rate of 1 mg/kg), lead (1,1 mg/kg; at a rate of 1 mg/kg), chromium (1,1 mg/kg; at a rate of 12 mg/kg) and cadmium (1 mg/kg; at a rate of 0,1 mg/kg). Cause of hypothyroidism in cattle from the Rostov region is iodine deficiency, imbalance of trace elements and anthropogenic contamination of the environment, thus, thyroid pathology as hypothyroidism is mainly of pluricausal nature that leads to the birth of calves with endemic goiter.