Genetic characterization of phenotypic traits in endangered Taishu horse breed and their breeding strategy.

This research provides a genetic characterization of the endangered Taishu horse and proposes a breeding strategy to conserve this breed. Key findings include identifying specific genes related to the horse’s coat color, body composition, and gait, and the essential role of genotyping for the conservation of this breed.

Genetic Profiling of the Taishu Horse

• The study analyzed the genetic make-up of 56 Taishu horses. Specifically, it investigated nine single-nucleotide variants and three indels (insertions or deletions) of nine genes that influence phenotypic traits such as coat color, body composition, and gait.
• Of the nine genes investigated, only three were polymorphic, meaning they displayed variation in the population studied.
• Associations were made between observed coat color phenotypes and respective genotypes. Interestingly, black Taishu horses showed unique seasonal color change – black in winter but turning light brown in summer.

Body Composition and Gait

• There were no observed DNA polymorphisms in the ligand-dependent nuclear receptor corepressor-like gene and very few polymorphisms in the myostatin gene — both of these genes are related to body composition.
• They also studied the body measurements of the horses, including withers height, chest circumference, cannon circumference, and body length, yet found no relationship between these physique characteristics and the genetic variants explored.
• In relation to gait, the gaited allele of the doublesex and mab-3 related transcription factor 3 gene was not detected. Instead, most Taishu horses exhibited a ‘trot’ phenotype, which was consistent with estimations.

Conservation of Rare Phenotypic Traits

• The paper emphasizes the importance of genotyping for conservation strategies, specifically for preserving the black and chestnut Taishu horses that are less common compared to bay horses.
• The insight yielded by this research will benefit breeders in their efforts to conserve not only the Taishu horse but also other declining native Japanese breeds, like the Noma and Miyako horses.