Hair macro- and microelement levels as estimates of mineral status in horses of stud and local breeds from different Russian regions

The optimal balance of chemical elements plays a vital role in the functioning of animal body. In horses, such balance is especially important because of specific hard work, in some cases on the verge of physiological limits. Besides, sometimes under the traditional technology of horse herd the rearing conditions may be extremal, for example, when horses are outdoors around the clock in severe winters of the northern Yakutia at extreme subzero Arctic temperatures. Estimate of mineral profile of a horse is the most important marker of physiological well-being, viability, productivity and adaptability to stresses. The purpose of this study was to identify levels of micro- and macroelements in hair of horses (Equus ferus caballus) of various genetic groups that are bred and used in various technological conditions in different regions of the Russian Federation. Totally, we used 198 hair samples of horses of stud breeds (Russian Trotter, Thoughbred, Purebred Arabian, Purebred Akhal- Teke) and local (indigenous) Bashkir, Kabardin, Mezenskaya, Vyatskaya breeds, Tuva and Yakut horses. The stud horses were kept at stables and the other in herds on pastures in 11 regions of the Russian Federation. In hair samples, 5 macroelements (Ca, K, Mg, Na, P) and 8 essential microelements (Co, Cr, Cu, Fe, I, Mn, Se, Z) were determined. Genetic determination of the content of macro- and microelements in the hair were evaluated in the Thoroughbred horse, Purebred Arabian and Purebred Akhal-Teke breeds (Stavropol Krai) kept under identical climatic conditions and common technology. Genetic profile was assessed for 16 autosomal DNA microsatellite loci, and the relationship between the level of homozygosity and distribution of chemical elements was evaluated in each of these breeds. All the studied groups significantly differed in hair chemical elements depending on genetic group (breeds), areal and rearing. Animals from the Republic of Sakha (Yakutia) had a deficit for 11 out of 13 chemical elements analyzed when compared to the average indices for all surveyed regions The Republic of Bashkortostan and the Republic of Kabardino-Balkaria shared 1242 the second place for the deficit of macro- and microelements, the Republic of Kalmykia and Stavropol Krai were the third and followed by Arhangelsk, Briansk and Lipetsk regions. The most favorable situation was in the Republic of Tyva and Krasnodar Krai where the surplus was registered for 12 and 11 elements respectively and some of them amounted up to 220 % compared to the average for the country. The advantage of stables keeping of horses, which provides the best balance of chemical elements in the body by regulation of nutrients in the diet, was observed. Hair mineral levels in horses of different origin correlated to their genetically homogeneous groups. Raising the level of hair macro- and microelements and an increase in heterozygosity of the three purebred breeds, as detected by 16 DNA microsatellite loci polymorphism, was found out to correspond. The Akhal-Teke breed that is distinguished by a greater heterozygosity was the most well-balanced for macro- and microelements. The micronutrient level database for horses of various breeds and breed groups form different Russian regions is of interest for the studying factors determining mineral metabolism in animals that should facilitate the innovative development of horse breeding.