Phenotypic and genetic analysis of reproductive traits in horse populations with different breeding purposes.

The research article presents an investigation into the role of reproductive traits on the economic efficiency of horse breeding. It suggests including age at first and last foaling, and interval between foalings, in breeding programs to maximize economic success.

Research Context

• The research was performed in response to a lack of detailed understanding of how horse populations’ reproductive traits could be utilised to optimise breeding programs.
• The researchers conducted a comprehensive analysis of data from eight different Spanish horse populations bred for various purposes.

Study Methodology

• A total of 696,690 records were evaluated, comparing reproductive parameters of both male and female horses such as age at first foaling (AFF), age at last foaling, average reproductive life and generational interval.
• For females, additional traits such as the average interval between foaling (AIF) and interval between the first and second foaling were studied.

Findings

• The researchers noted clear differences in reproductive traits across sexes and breeds. These discrepancies were attributed to the variations in management practices, breeding goals, and population status rather than physiological differences.
• Riding mares were found to have the earliest age at first foaling and more intensive reproductive use.
• The earliest male age at first foaling was observed in the males intended for meat production, though these males had a shorter reproductive life compared to others.

Genetic Factors

• Heritability estimates, which range between 0.02 to 0.42 in females and 0.04 to 0.28 in males, were used to demonstrate the existence of a genetic component in these reproductive traits.
• Sport Horses were found to have higher average heritability values.

Recommendations for Breeding Programs

• The study recommends selection based on AFF due to its medium to high heritability and the positive correlation with other significant reproductive aspects.
• The research further suggests including the AIF in breeding programs specifically for sport horses as it impacts the duration of gaps between foalings and affects the dam’s reproductive performance, selective intensity, genetic gain and overall genetic improvement.
• Crafting breeding programs with these factors in mind can potentially enhance the economic efficiency of horse breeding operations.