# Analysis of Population Structure in Hungarian Coldblood Horses Based on Pedigree Information

## TL;DR

This study analyzes the genetic structure of the Hungarian Coldblood horse breed using pedigree data to support conservation efforts and reduce inbreeding.

## Contribution

The study provides a detailed analysis of inbreeding and genetic bottlenecks in the Hungarian Coldblood horse using multiple inbreeding coefficients.

## Key findings

- The Hungarian Coldblood horse experienced a significant bottleneck in its breeding history.
- Inbreeding is more pronounced in recent generations, as shown by Kalinowski’s decomposition.
- The actual breeding stock has a higher inbreeding coefficient compared to the total population.

## Abstract

Maintaining genetic variability is the most important purpose of animal conservation programs. The Hungarian Coldblood horse is an indigenous breed which is descended from horses traditionally used by peasants. In the last century, the role of horses has changed, and they have been replaced by technical innovations and motorization, thus reducing the population size and genetic diversity. The aim of this study was to provide information on the current breeding stock and to support breeders’ associations in their gene conservation work for this endangered local breed. The pedigree quality, generation intervals, probability of gene origin, and inbreeding were assessed. We found that the breed had a large bottleneck effect during its breeding history. The level of inbreeding was measured using different methods, such as Ballou’s, Wright’s, and Kalinowski’s coefficients.

The Hungarian Coldblood horse was developed in the 1920s by crossing local mares with draft horses imported from Belgium and France, and was approved as an official horse breed in 1954. The aim of the study was to analyze the quality of the pedigree, generation interval, gene origin, and inbreeding. The pedigree information was received from the Hungarian Coldblood Horse Breeding Association. The studbook data of the registered animals up to 2023 were evaluated. Two reference populations were chosen: horses having offspring in 1989 and 2023. The final database contained 21,699 horses. Pedigree data of the total population and the actual breeding stock were analyzed using Endog 4.8. and Grain 2.2. software. The complete generation equivalent was 4.64 and 7.72, whereas the average maximum generations was 7.90 and 13.06 for the total and reference population, respectively. There were significant differences between the parent–offspring pathways of generation intervals. In the total stock, the first 10 individuals are present in 26.71%, while in the actual breeding stock, they are present in 37.84%. The average Wright’s inbreeding coefficient was 1.13% and 2.35% in the total population and the actual breeding stock. Kalinowski’s new decomposition of inbreeding showed that inbreeding does not originate from the past; inbreeding is stronger in more recent generations. There was a reasonable bottleneck effect. A more careful mating design might be needed to avoid inbreeding in the future.