Genetic, historical and breeding aspects of the occurrence of the tobiano pattern and white markings in the Polish population of Hucul horses – a review

The studbook of Pura Raza Menorquina horses only permits the use of black-coated animals with a small quantity of white marks as breeding stock. Its breeding program uses linear mor-pho-functional traits as selection criteria. Our aim was to estimate the genetic parameters of linear morpho-functional traits, and reveal relationship of quality of black coat color (QB) and percentage of white marks (WM) with the other morphological and functional linear traits in this breed. A total of 46 linear traits were scored by four appraisers using seven classes, with a total of 772 records from 333 animals (≥4 years old). Univariate animal models using a Bayesian approach were used, with a pedigree of 757 animals. Sex (two) and appraiser-season (13) were included as fixed effects, age as a linear covariate, and permanent environmental and additive genetic as random effect. The heritabilities of the morpho-functional traits were low to medium (0.09–0.58) and matched the range in the bibliography. Heritabilities for coat color traits were 0.36 for QB and 0.23 for WM. The highest genetic correlations were obtained between QB and upper neck line (0.816) and between WM and form of the hoof (0.638). The negative signs of most of the genetic correlations between WM and the functional traits is also remarkable, contributing to the selection of functional traits against the presence of white marks in this population. A clear genetic differentiation was observed between animals with better breeding values for QB and WM, corroborated by a study on founders. In conclusion, QB and WM could show different genetic backgrounds.

Section: Resultssupporting

confidence: 70%

Section: Resultsmentioning

confidence: 99%

Morpho-Functional Traits in Pura Raza Menorquina Horses: Genetic Parameters and Relationship with Coat Color Variables

Perdomo-González

Paredes

Valera

et al. 2022

“…We identified multiple solid-colored horses with the W20/W32W35 and W35/W34W35 genotypes. The Tobiano and W35 alleles have been reported to not always produce any white markings (reviewed in [4,23]). The amount of depigmentation is highly variable for single alleles and allelic combinations of these variants, even within the same genotype, because of the stochastic nature of pigmentation (Figure 2).…”

Section: Discussionmentioning

confidence: 99%

Population Analysis Identifies 15 Multi-Variant Dominant White Haplotypes in Horses

McFadden,

Vierra,

Robilliard

et al. 2024

The influence of a horse’s appearance on health, sentimental and monetary value has driven the desire to understand the etiology of coat color. White markings on the coat define inclusion for multiple horse breeds, but they may disqualify a horse from registration in other breeds. In domesticated horses (Equus caballus), 35 KIT alleles are associated with or cause depigmentation and white spotting. It is a common misconception among the general public that a horse can possess only two KIT variants. To correct this misconception, we used BEAGLE 5.4-phased NGS data to identify 15 haplotypes possessing two or more KIT variants previously associated with depigmentation phenotypes. We sourced photos for 161 horses comprising 12 compound genotypes with three or more KIT variants and employed a standardized method to grade depigmentation, yielding average white scores for each unique compound genotype. We found that 7 of the 12 multi-variant haplotypes resulted in significantly more depigmentation relative to the single-variant haplotypes (ANOVA). It is clear horses can possess more than two KIT variants, and future work aims to document phenotypic variations for each compound genotype.

“…Moreover, they are one of the oldest primitive breeds originating from crossing with breeds such as Tarpans, Przewalski horses, Tatar and Turkish horses, as well as horses with Noric blood. As of today close to 1300 horses are maintained in the Polish genetic resources conservation program which is aimed to maintain their genetic variablity [ 23 , 25 ]. In regard to draft horses, two breeds Sokolski and Sztumski were used in this study, both of which are maintained within Polish genetic resource conservation program.…”

Section: Introductionmentioning

confidence: 99%

“…[ 23 , 26 ]. More information about the breeds used in this study can be found in: for Sokolski and Sztumski [ 21 , 23 , 26 ], for Polish Konik and Hucul [ 23 , 24 , 25 ] and for Malopolski horses [ 23 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

Assessment and Distribution of Runs of Homozygosity in Horse Breeds Representing Different Utility Types

Szmatoła

Gurgul

Jasielczuk

et al. 2022

Self Cite

The present study reports runs of homozygosity (ROH) distribution in the genomes of six horse breeds (571 horses in total) representing three horse types (primitive, light, and draft horses) based on the 65k Equine BeadChip assay. Of major interest was the length, quantity, and frequency of ROH characteristics, as well as differences between horse breeds and types. Noticeable differences in the number, length and distribution of ROH between breeds were observed, as well as in genomic inbreeding coefficients. We also identified regions of the genome characterized by high ROH coverage, known as ROH islands, which may be signals of recent selection events. Eight to fourteen ROH islands were identified per breed, which spanned multiple genes. Many were involved in important horse breed characteristics, including WFIKNN2, CACNA1G, STXBP4, NOG, FAM184B, QDPR, LCORL, and the zinc finger protein family. Regions of the genome with zero ROH occurrences were also of major interest in specific populations. Depending on the breed, we detected between 2 to 57 no-ROH regions and identified 27 genes in these regions that were common for five breeds. These genes were involved in, e.g., muscle contractility (CACNA1A) and muscle development (miR-23, miR-24, miR-27). To sum up, the obtained results can be furthered analyzed in the topic of identification of markers unique for specific horse breed characteristics.