Phenotypic and Genetic Evaluation of Morphometric and Dynamic Traits in Mangalarga Horses

Genetic evaluation of morphometric and locomotor traits supports objective selection, avoiding exclusive reliance on subjective methods that may fixate breed traits over functionality or cause undesirable indirect selection.

To evaluate genetic and phenotypic parameters for morphometric and dynamic traits in horses of the Mangalarga breed.

The pedigree included 212,361 animals born between 1919 and 2019. Phenotypic subsets for morphometric and dynamic traits comprised 54,617 and 45,010 horses, respectively, born between 1977 and 2019. Variance components were estimated using an Animal Model via the BLUPF90+ software family.

Phenotypic means±SD and heritabilities±SD for morphometric traits were withers height (153.86±4.43 cm; 0.58±0.01), thoracic perimeter (178.67±7.97 cm; 0.40±0.01), and cannon bone perimeter (19.03±0.96 cm; 0.21±0.01). Dynamic traits were movement (12.63±1.45 points; 0.34±0.01), dynamic limbs (9.03±1.32 points; 0.26±0.01), canter (4.23±0.69 points; 0.22±0.01), comfort (11.49±1.14 points; 0.29±0.02), and total dynamics (38.37±3.03 points; 0.32±0.02). Phenotypic correlations ranged from 0.06±0.01 (cannon bone perimeter and comfort) to 0.87±0.00 (movement and total dynamics). The weakest genetic correlation was between dynamic limbs and cannon bone perimeter (-0.01±0.04), and the highest between movement and total dynamics (0.92±0.01). The strongest negative genetic correlation was between movement and cannon bone perimeter (-0.21±0.04).

Moderate to high heritability estimates demonstrate the selection potential of these traits. However, the genetic antagonism between movement and cannon bone perimeter requires a nuanced approach. These findings provide the breed's first comprehensive breeding values, offering effective tools for the development of selection indexes that weight gait improvement while setting minimum constraints for bone structure.