OLEG KAZBEKOVICH GOGAEV, KHETAG ESTAEVICH KESSAEV, BORIS SERGEEVICH KALOEV, MURAT EKHYAEVICH KEBEKOV AND TIMUR TAZRETOVICH TARCHOKOV
Abstract
The study of the formation of the skin structure and hair coat that has not only a general biological but also a big practical value, especially for sheep of the Romanov breed, is a part of the cognition problem of the regularity of the individual development of animals. Method: The sampling of skin was carried out by means of a special tool (selecting knife) with a diameter of 2 cm, section area 3.14 cm2. The selecting knife allows selecting the skin samples with minimal harm for the animal and less labour input. The preparation of the skin drugs and their research was performed according to the method of Diomidova et al. (1957). It was revealed that in postembryonal period there is a further growth and differentiation of the skin structure, regularity and rate of which depends upon the age. The highest rate of the skin growth and formation of hair fibers from the embryo hair follicles of the Romanov sheep is during the first months of life and they stop by the age of 9 months. The other insignificant changes are related to the conditions of the season, feeding and growing. The formation of the hair fibers from the embryo hair follicles stops by the age of 9 months. The hair of the Romanov sheep consists of beard hair and fur hair. At birth, the beard hair exceeds the length of the fur hair 2.7-3.0 times and at the age of 6 months, on the contrary, the fur hair exceeds the beard hair 1.7-1.8 times. The average thickness of the main types of fibers increased with time and at the same time the fur hairs had the biggest thickening (growth factor 2.53), the average thickness of the beard hairs increased 1.7 times. As a result of the more intensive growth of length and thickness of the fur hairs, the sharp change of their percentage with age occurred. If the specific weight of the fur hairs of newborn lambs was 11.1%, at the age of 6 months it grew up to 73.2%. The conducted research allows to have a scientific grounding for the correct development of the measures directed to the improvement of the sheep breeding production of outputs.