DYNAMICS OF TESTOSTERONE AND CHOLESTEROL CONCENTRATION IN FOXES (Vulpes vulpes) OF DIFFERENT COLOR TYPES IN POSTNATAL ONTOGENESIS
Authors: Berezina Yuliya A. , Bespyatykh Oleg Yu. , Perevozchikova Maria А. , Plotnikov Igor A. , Domsky Igor A. , Syutkina Anna S. 
Published: December 2024

Background. Currently, a large amount of reference information has been accumulated in the field of physiology of fur-bearing animals. The morphology and biochemistry of blood, immunological parameters were studied in detail. At the same time, there is significantly less data on the endocrine system and its effect on reproduction, and there is no information on the dynamics of cholesterol and testosterone in male foxes of different color types. There are few publications, especially those related to ontogenesis, that would analyze the formation of steroidogenesis. Considering that in the literature data on the endocrine system and its influence on the reproduction of fur-bearing animals are found in isolated cases, and there is no information on the dynamics of cholesterol and testosterone in male foxes, it is of great scientific and practical interest to clarify the ontogenetic dynamics of testosterone concentration in foxes of different color types and its relationship with cholesterol due to the latter’s direct participation in steroidogenesis. Therefore, the purpose of the study: to study the dynamics of testosterone and cholesterol concentrations in male foxes of different color types in postnatal ontogenesis.
Materials and methods. The studies were carried out in the veterinary laboratory of the Federal State Budgetary Institution VNIIOZ named after. prof. B.M. Zhitkova (Kirov, Russia). The study used young domesticated foxes (Vulpes vulpes L., 1758), bred at Vyatka Animal Farm LLC (Kirov region, Russia). From clinically healthy male foxes of two color types: silver-black and red, 2 groups of 16 animals each were formed. Ontogenetic development was observed in animals aged from 45 days to 10 months. By the age of 9 months, animals become sexually mature and participate in the breeding process, which for foxes happens once a year - in January-February. Blood was taken from foxes at the age of 45 days, 4, 6, 9 and 10 months, which corresponded to the seasons of the year in July, September, November, February and March. The concentration of testosterone and cholesterol in the blood serum was determined. Testosterone was studied on an automatic microplate photometer Immunochem-2100 (High Technology Inc., USA) by enzyme-linked immunosorbent assay using a test system produced by Hema-Medica LLC (Russia). Cholesterol in blood serum was determined on a semi-automatic biochemical analyzer "Biochem SA" (USA) using kits from "Ecoservice" (Russia). The results were processed by statistical methods. The Mann-Whitney test was used to assess the significance of differences. The level of statistical significance of the obtained differences between the compared samples was accepted at p<0.05.
Research results. A strong direct statistical relationship (r=0.993) was established for the concentration of testosterone in the blood serum between silver-black and red foxes during postnatal ontogenesis. Moreover, the concentration of testosterone in the red fox is higher than in the silver-black one (p<0.05). A strong direct relationship (r=0.880, p<0.05) between the concentration of cholesterol in the blood of animals and the color color was established. In the blood serum of males, the content of testosterone and cholesterol is closely related in both silver-black (r=0.960, p<0.05) and red foxes (r=0.980, p<0.05).
Conclusion. This study provides new data on differences in cholesterol and testosterone levels in foxes of different color types. These results may have important implications for understanding the biological differences between different species and types of animals, as well as the impact of hormonal changes on overall health and reproductive processes.