Mitotic processes in hair follicles and the morphostructure of sheep skin upon inclusion of a water-soluble fatty acid complex into their diets

The inclusion of fat supplements in sheep diets, particularly ω-3, ω-6, and ω-9 fatty acids, affects their productivity and product quality. In this regard, a study was conducted to examine the effect of feeding ewes a water-soluble complex of fatty acids (linoleic, oleic, palmitic, arachidonic, stearic, and linolenic) as part of their compound feed on the morphostructure of the skin and hair follicles. The study subjects were skin samples taken at the end of the experiment from the shoulder blade area. It was found that the fatty acid emulsion did not directly affect the diameter of secondary hair follicle bulbs but led to a statistically significant increase in the diameter of primary follicle bulbs, from 269.8 μm in the control group to 292.2 μm in the experimental group (P < 0.05). The increase in energetic nutritional value of the diet resulted in an increase in mitotic activity for both primary (P < 0.05) and secondary follicles (P < 0.01). Higher specific mitotic activity rates (P < 0.05) were positively correlated with wool growth. It was shown that the total skin thickness and epidermal thickness in ewes of both the control and experimental groups practically do not differ. However, in animals of the experimental group, although not statistically significant, the thickness of the reticular layer of the dermis increased, whereas the papillary layer decreased, leading to a lower ratio between these layers. The latter has a direct impact on dermal strength. As a result of studying individual morphometric indicators of the secretory components of the skin, it was established that the nutritional factors we used do not significantly affect the width of the sebaceous gland lobes. However, ewes in the experimental group, despite the lack of statistical significance, had a higher density of hair follicles (56.2 vs. 53.8 follicles/mm) compared to the control group. Meanwhile, the ratio of secondary follicles to primary follicles was 7.08 in the experimental group versus 6.04 in the control group.