Retrospective and statistical analysis of breeding management on the Italian Heavy Draught Horse breed.

The research study examines breeding management approaches for the Italian Heavy Draught Horse breed with a focus on mare reproduction efficiency and stallion ‘genetic lifespan’. Different stud rearing systems and various mare and stallion ages are analyzed to determine the optimal conditions for successful breeding and genetic superiority.

Objective

The research is aimed at improving breeding management efficiency of Italian Heavy Draught Horse breed at stud farm level.

• The first purpose of the study was to assess the risk of unsuccessful mares reproductivity that had their first foal at early (3 years) or normal age (4 years) in conjunction with various stud rearing systems.
• The second objective revolved around the evaluation of the duration young 2-year-old stallions maintain a genetic superiority over older stallions. This helped to determine a ‘genetic lifespan’ that assures young stallions can be used effectively for reducing the cost of services.

Methods

• A retrospective analysis of reproductive performance of 1513 mares at their first and second foaling was conducted. Mares had their first foal either at 3 or 4 years of age at stud farms with different rearing systems (stable, feral, or semi-feral).
• The risk of unsuccessful reproduction in the next season was modeled using logistic regression analysis. The variables involved were the interaction of the mare’s age at first foaling and the rearing system used.
• The ‘genetic lifespan’ of young stallions was estimated by comparing estimated breeding values (EBVs) of young stallions and the mean EBV of all proven stallions in a particular year. This analysis involved looking into individual differences and annual EBV decrease rate.

Findings

• In comparison with the second foal birth at 4 years in a stable system, the greatest risk of unsuccessful reproduction was at age 3 years in both feral (+167%) and semi-feral conditions (+91%).
• Young stallions demonstrated a 0.50 s.d. higher EBV at the first evaluation than proven stallions. They had a mean annual decrease in EBV of 0.07 s.d./year on proven stallions.
• Optimal breeding management in stud farms could be achieved by limiting foaling at age 3 years, especially in feral and semi-feral rearing systems, and by using young stallions for 3 to 4 years to maintain a solid selection differential with older proven stallions while also reducing the cost of services.

Implications

The research indicates that successful breeding management in Italian Heavy Draught Horse breed is dependent on both the mare’s age at first foaling and stallion ‘genetic lifespan’. By combining age and rearing system considerations with a stallion’s ‘genetic lifespan’, farms can continue to advance genetically while also reducing costs. However, a reduced selection differential with older stallions over time may slow genetic improvement. The findings offer important insights into how to optimize breeding management in stud farms.