Genetic analysis of the Hungarian population of endangered Hucul horses

Abstract

The population genetic evaluation of the Hungarian Hucul horse population was performed based on pedigree records. Herd book data of registered Hucul horses available up to 2016 were analysed using ENDOG (Gutierrez and Goyache 2005) and POPREP (Groeneveld et al. 2009) on the whole population (WP) as well as on the reference stock (RS) (breeding stock registered in 2016). Inbreeding coefficients were 5.57% (WP) and 7.18% (RS). Average relatedness was 10.39% in WP and higher in RS (12.67%). Effective population size was 52.32. Generation interval was 13.01 years for WP and 10.99 years for RS. The values for equivalent complete generations were 6.07 and 8.75, for the maximum number of generations 14.11 and 19.16, and for the number of full generations traced 3.77 and 5.50 for WP and RS, respectively. The effective number of founders (f<sub>e</sub>) was 23 both for WP and RS. The effective number of ancestors (f<sub>a</sub>) was 20 in WP and lower in RS (16). The f<sub>a</sub>/f<sub>e</sub> ratio was 0.869 in WP and 0.696 in RS. Founder genome equivalent (f<sub>g</sub>) was 9.618 in WP and 5.790 in RS. The f<sub>g</sub>/f<sub>e</sub> ratio was 0.481 in WP and 0.361 in RS. The study revealed that both the inbreeding coefficient and the average relatedness were high. The above mentioned ratios indicated loss of genetic diversity in the Hungarian Hucul population.

Historical Changes and Description of the Current Hungarian Hucul Horse Population

“…Pedigree completeness data also suggest more deep pedigree information for the actual Hungarian breeding stock, as well as for animals born after 1980. Recently computed numbers are slightly higher than those reported by [ 4 ]. Recent equivalent complete generations are higher than was found for the Asturcón pony population [ 7 ].…”

“…Following recommendations of the Food and Agriculture Organization (FAO), the Hucul breed is classified as vanishing breed and needs a conservative breeding program [ 1 ]. The genetic structure and diversity of local present populations were evaluated for the Slovak [ 2 ], the Polish [ 3 ] and the Hungarian [ 4 ] populations, but changes across birth-year time periods were not studied yet.…”

Level of Inbreeding in Norik of Muran Horse: Pedigree vs. Genomic Data

“…1. The decrease of pedigree completeness across the generations of ancestors in horses was well documented in previous studies (Pavlík et al, 2014;Vostrý et al, 2017;Somogyvári et al, 2018;Halo et al, 2018). Compared to this study, Druml et al (2009) reported for Austrian Noriker higher pedigree completeness.…”

“…For example Pjontek et al (2012) reported for Slovak Sport Pony, Shagya Arabian and Hucul horses bred in Slovakia inbreeding at level 2.67, 3.95 and 6.26%, respectively. Similarly, Somogyvári et al (2018) indicated in small endangered population of Hucul horse average inbreeding coefficient 5.57%. The individual genomic inbreeding (F ROH ) was derived from distribution of ROH segments in the Norik of Muran horse genome.…”

“…Pjontek et al, 2012;Vostrá-Vydrová et al, 2016;Vostrý et al, 2017). By slowing down inbreeding progress and avoiding the mating of related individuals, genetic variability can be maintained or at least its decreasing can be slowed down whereby the preservation of the breed may be attained during a longer period (Somogyvári et al, 2018). Traditionally, the level of inbreeding within livestock populations including horses is estimated based on the pedigree data.…”