Estimation of genetic and non-genetic effects influencing coat colour in black horses

Abstract

The aims of this study are the quantitative characterisation of the coat colour in the black variety of the Old Kladruber Horse breed, the estimation of the coat colour genetic parameters, and the determination of the factors that influence coat colour intensity. A total of 252 horses aged 1–24 years were included in the study. The colour parameters were taken using a Konica Minolta spectrophotometer CM-2500d at four different body parts during the summer and winter seasons, resulting in 1748 phenotypic records. The possible effects of sex, season, housing system, age and body part on the spectrophotometric parameters were analysed. The results confirmed that the intensity of the black coat colour can be influenced by a number of factors (sex, season, housing system, and age). The mares showed more red and yellow colour compared to the stallions. In the winter season, the horses had a lighter colour with a lower proportion of reddish-brown hairs. Horses kept outdoors, especially in the summer months, had a lighter colour with a higher proportion of red and yellow. Although the age was statistically significant, no specific trend was observed. The differences in colour found between body parts (neck, shoulder, belly, and croup) are in line with current knowledge – reddish fading in the blacks primarily occurs in the belly region. The estimated heritability values suggest possible multifactorial inheritance, especially with regards to the reddish tinge in hairs (h<sup>2</sup> = 0.20 to 0.29 according to body part).