Genetic Parameters of Linear Type Traits Scored at 30 Months in Italian Heavy Draught Horse.
Authors: Folla Fabio, Sartori Cristina, Mancin Enrico, Pigozzi Giuseppe, Mantovani Roberto
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Linear Type Trait Genetics in Italian Heavy Draught Horses The Italian Heavy Draught Horse breed traditionally relies on linear type trait (LTT) evaluation of six-month-old foals to guide breeding decisions, yet all breeding candidates are re-scored at approximately 30 months before official stud book admission. Researchers analysed 19 years of assessment data across 14 LTT and an overall score in 5,835 mares and 856 stallions using an animal model to determine whether adult evaluations could replace foal scoring and thereby reduce selection programme costs. Heritability estimates at 30 months ranged considerably—from just 0.03 for upper line length to 0.40 for frame size—with traits of primary breeding interest (head size and expression, temperament and movement, fleshiness, fore and rear diameter) showing moderate heritability values between 0.21 and 0.31. Strong genetic correlations (averaging 0.73) emerged amongst traits associated with muscular development, and positive genetic trends were already evident in traits previously selected via foal data. These findings suggest that adult-stage LTT evaluation is genetically viable for selection purposes in this breed, potentially streamlining breeding programmes without compromising response to selection, though the low heritability of some structural traits warrants careful consideration when designing revised assessment protocols.
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Practical Takeaways
- •Breeders can consider using adult (30-month) conformation evaluations instead of foal assessments for selection decisions in Italian Heavy Draught Horses, potentially reducing breeding program costs while maintaining genetic progress
- •Traits showing moderate-to-good heritability (0.21-0.31) at 30 months—head size, temperament, muscular development, and bone diameter—are reliable selection targets in this breed
- •Strong genetic correlations between muscular development traits suggest selecting for one trait will improve correlated traits, improving selection efficiency
Key Findings
- •Heritability of linear type traits at 30 months ranged from 0.03 to 0.40, with traits of selection interest (head size, temperament, fleshiness, fore/rear diameter) showing heritability between 0.21-0.31
- •High genetic correlations (average 0.73) were found among traits related to muscular development
- •Positive genetic trends were observed in selection interest traits when using adult evaluations, matching trends from foal-based selection
- •Selection based on 30-month evaluations is feasible and may reduce costs compared to foal-based selection programs