Changes of coat cover in primitive horses living on a reserve

Abstract

Changes in the coat cover are important for mammalian thermoregulation. This is especially true where variable environmental conditions exist throughout the seasons. Coat cover shedding is the replacement of old coat hair with new hair. The process differs in various equids. The aim of the study was to examine the changes in the coat of primitive Polish Konik horses living on a reserve in southeast Poland (50.6319° N). The reserve is located in a temperate climate. The mean temperature is below 0°C in winter (December 8 to March 9) and over 15°C in summer (June 8 to September 8). Five adult mares were included in the study. The study used a specific methodical approach to quantitatively assess coat cover changes. Photos were taken once every 2 wk throughout the whole year to document the state of the mares' coat. MultiScanBase software was used to analyze 260 photos. The percentage of the skin surface covered with short hair in relation to the surface of the body (without the head, neck, and limbs; short hair body [SHB]) was determined. To assess the topography of coat changes, surface parts covered with short hair within 6 regions of the body (shoulder, back, chest, loins, belly, and hindquarters; short hair part [SHP]) were considered separately. The regression coefficient was calculated for the SHB and the air temperature. Correlations in SHP and SHB between the left and right sides of the body were determined. The correlations within the right side of the body concerned particular SHP. As the results show, the coat changes take place at the same time on both sides of the horse's body. In spring, the winter hair is shed, and in the fall, the winter hair grows in longer. High regression (0.901; < 0.0001) proved that air temperature strongly affected the coat changes. The most important increase of SHB occurs in April and the first half of May, whereas the main decrease of SHB takes place in September. Changes between SHP are highly correlated (0.967-0.994; < 0.05). Spring and fall coat changes demonstrate that the shoulders, back, and loins require the winter cover for a longer time than the chest and belly, whereas the hindquarters are the least demanding in this respect. The phenomenon may be associated with, among others, the stronger effect of rain and snow on the upper parts of the body.