Genetic variability in Hanoverian warmblood horses using pedigree analysis.

The research study examined the genetic diversity and sources of genetic contributions in a population of 310,109 Hanoverian warmblood horses, specifically focusing on horses born between 1980 and 2000.

Research Context and Methodology

• The researchers used data from over 310,000 Hanoverian warmblood horses in their analysis.
• The primary focus of the study was on gene contributions and genetic variability of the Hanoverian horses born in the period of 1980 to 2000.
• The study also delved into problematic issues such as the coefficients of inbreeding, an issue in many selectively bred animal populations.
• Two more specific populations within the main sample were evaluated: Hanoverian stallions born between 1980 and 1995 and Hanoverian breeding mares born in the same period that produced registered foals.

Key Findings

• The researchers noted an average complete generation equivalent of 8.43 for the overall reference population.
• The mean coefficient of inbreeding — how related the individuals in the population are — was found to be 1.33% for the reference population, 1.19% for the stallions, and 1.29% for the breeding mares.
• The effective number of founders — individuals who contribute genes to the current population — was lowest in the overall population (244.9) and highest in stallions (364.3).
• A similar measure, the ratio between the effective number of founders and the effective number of ancestors, was between 3.06 and 3.25 across the populations.
• The effective population size, which considers both the number and distribution of reproduction individuals, was 372.34 in the overall reference population.

Contributions from Foreign Populations

• The study identified that English Thoroughbreds contributed around 35% of the genes to the Hanoverian population, increasing to 39% in the stallion population.
• Contributions from Trakehner and Arab horses were substantially smaller, at about 8% and 2.7%, respectively.

Genetic Impact of Specific Ancestors

• Researchers noted several male ancestors with substantial contributions to the current gene pool, including Aldermann I from the A/E line, Fling from the F/W line, and Absatz from the Trakehner line.
• The breeding mare Costane made significant genetic contributions across all three studied populations (reference, stallions, and breeding mares).
• From 1996, the stallions Weltmeyer and Donnerhall had the most profound genetic impact on the Hanoverian horse population.