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Breeding Value Estimation Based on Morphological Evaluation of the Maremmano Horse Population through Factor Analysis
by
, and
Andrea Giontella
1,*,
Maurizio Silvestrelli
1,
Alessandro Cocciolone
2,
Camillo Pieramati
1 and
Francesca Maria Sarti
2 1
Department of Veterinary Medicine—Sportive Horse Research Center, University of Perugia, Via S. Costanzo 4, 06126 Perugia, Italy
2
Department of Agricultural, Food and Environmental Sciences, University of Perugia, Borgo XX Giugno, 74, 06121 Perugia, Italy
*
Author to whom correspondence should be addressed.
Animals 2024, 14(15), 2232; https://doi.org/10.3390/ani14152232 (registering DOI)
Submission received: 30 April 2024
/
Revised: 22 July 2024
/
Accepted: 28 July 2024
/
Published: 31 July 2024
(This article belongs to the Special Issue Advances in Equine Genetics and Breeding)
Simple Summary
Horse body conformation is an important aspect to evaluate in sport horse selection since the overall body shape determines the limits of the range of movement and function of the horse and, ultimately, its future performance. The genetic improvement of this breed is under the control of the National Association of Maremmano Breeders (ANAM), the first Italian association to use a continuous evaluation scale to evaluate the horses enrolled in the Studbook in the early 1990s. Morphological scoring is a common evaluation method for domestic animals. People employed in this type of role must be able to translate their judgements regarding certain features of the animal’s body into numbers or letters, thus avoiding the need to measure the animal. Only a few aspects of the horse’s body conformation are actually measured since this activity is difficult and expensive. This study proposes an easier approach to horse scoring in order to obtain genetic proof of morphological traits and, consequently, to support breeders in making targeted selection decisions. Three new factors were computed and summed through an unique New Estimated Breeding Value (NEBV1), with the purpose of supporting breeders in adopting an easier and more accurate selection approach.
Abstract
Morphological scoring is a common evaluation method for domestic animals. The National Association of Maremmano Breeders (ANAM) has provided a dataset containing the records of 600 horses, four metric measurements (cm) and 24 traits with a continuous evaluation scale, each one with 15 classes. Moreover, a body condition score (BCS) with five classes is included. In this study, factor analysis was conducted to create a small number of informative factors (3) obtained from these traits, and a new BLUP-AM-MT index was established. The New Estimated Breeding Value (NEBV1) of each horse was computed by adding the genetic indexes of the three factors, with each one multiplied using a coefficient indicated by ANAM. The practical feasibility of the NEBV1 was evaluated through Spearman correlations between the rankings of the NEBV1 and the rankings of the BLUP-AM-MT, estimated through the four biometric measures and the morphological score (MS) assigned to each horse by the ANAM judges. The factorial analysis was used to estimate three factors: the “Trunk Dimension”, “Legs” and “Length”. As the explained variance was only 32%, the model was rotated, and the heritability of the three factors were 0.51, 0.05 and 0.41, respectively. After rotation, the estimated correlations between the new NEBV1 and the biometric measures were improved. These results should encourage breeders to adopt a breeding value index that takes into consideration the factors derived from all the variables observed in the morphological evaluation of the Maremmano. In this way, breeders can use it to select the best animals for breeding.
