Advancing equine genomics: the development of a high density Axiom_Ashwa SNP chip for Indian horses and ponies

Abstract

The unique horse and pony breeds of India are declining at an alarming rate. These horses have been integral to the Indian culture and customs for centuries and represent a valuable genetic resource. It is imperative to harness the potential of this equine genetic resource that urgently needs conservation. The study highlights the design and development of a high density SNP array, the Axiom_Ashwa to aid in the genetic analysis and conservation efforts for Indian horse and pony breeds. With 613,950 SNPs, this chip offers extensive genome coverage having an average inter-marker distance of 4 kb. The Axiom_Ashwa has been validated on a larger set of diverse indigenous samples as well as Thoroughbreds, demonstrating a high call rate of 99.4% and robustness for genotyping indigenous breeds. Linkage disequilibrium (LD) analysis showed higher average LD in Indian breeds compared to exotic breeds, suggesting a limited effective population size and recent bottlenecks. Phylogenetic and population stratification analyses using PCA and DAPC clearly distinguished horses, ponies and Thoroughbreds, confirming the efficacy of the Axiom_Ashwa chip. These findings underscore the urgent need for conservation efforts for Indian horse breeds, which have experienced significant drop in population size. The Axiom_Ashwa SNP chip offers advantages such as cost-effectiveness and high throughput, providing a more accurate genetic representation of Indian horses.

Keywords: DAPC; Equine; Genetic diversity; Phylogeny; SNP array.