Genetic structure and genome-wide association study of the traditional Kazakh horses.

This research was focused on studying the genetic structure of traditional Kazakh horses and to identify single nucleotide polymorphisms (SNPs) — variations in a single genetic sequence — that are related to the animals’ size and weight. The study concluded that the various traditionally defined types of Kazakh horses should be considered as one breed. They also found that Kazakh horses have more genetic diversity than other well-known breeds, and they discovered a set of 60 genes that may influence horse size and weight.

Genetic Structure of Kazakh Horses

• The researchers conducted SNP genotyping on six distinct types of traditional Kazakh horses, using a microarray-based method. This led to a comprehensive analysis of the genetic structure of these horses.
• The traditional breed distinctions were not supported by the genetic data. Despite expected variations, the study showed a lack of substantial genetic diversity between the horse breeds and populations, indicating that all studied types should be considered a single breed, the ‘Kazakh horse’.
• Principal component analysis, ADMIXTURE, distance-based analyses, and evaluation of population parameters provided evidence of the lack of genetic variation across Kazakh horse breeds. This led the researchers to redefine the Kazakh horse breed to include all studied types and subtypes.

Genetic Diversity Comparison

• Comparing the genetic diversity of Kazakh horses with previously published data on global horse breed diversity showed that Kazakh horses possess relatively high individual diversity compared to internationally recognized breeds.
• The Mongolian and Tuva horse breeds were identified as the closest relatives, demonstrating similar patterns of internal variability.

Genome-Wide Association Analysis

• The genome-wide association analysis was conducted to detect SNPs related to horse size and weight as these traits directly influence meat productivity in horses.
• They identified a set of 60 SNPs that are associated with horse size and weight. These SNPs are linked with genes involved in the development of various systems such as connective tissues, the bone system, nervous system, immune system regulation, among others.

Implications

• This study is novel in introducing Kazakh horses as a potential genetic source for horse breeding and selection on the domestic and international levels, given their unique genetic structure and high diversity.
• The identified SNPs may help breeders select for size and weight traits, which could influence the productivity of meat from these horses.