Prevalence, risk factors and genetic parameters of cresty neck in Pura Raza Español horses.

The research paper investigates the prevalence, possible associated factors, and inheritability of a morphological defect known as “cresty neck” in the Pura Raza Español horse breed, indicating a significant proportion of these horses are affected and suggesting selective breeding to reduce the condition.

Study Design and Methods

• The research used a cross-sectional analysis of a worldwide database, consisting of 10,929 Pura Raza Español horses from 24 different countries.
• Measurements of these horses were noted, such as their cresty neck score being assigned on a 9 point scale, girth-to-height ratio, height at the withers, length of neck, the junction point between head-neck and neck-body.
• Further, a Bayesian genetic animal model was applied. It models the systematic effects like the girth-to-height ratio, the age of the horse, its sex, coat color, and the geographical area of the horse’s stud.
• In the model, individual variations (animal effect) and unexplained variations (residual effects) were included as random effects.

Main Findings

• The study revealed that 8.91% of the horses from this population had a cresty neck score of 5 or more. This score is crucial as it is the threshold for the penalty or disqualification in the breed’s studbook.
• The researchers found that the age, sex, coat color, and stud geographical area were significantly related to the cresty neck score. It means that these factors play a key role in the incidence of this morphological defect.
• The report estimated that the heritability coefficient for the cresty neck score was 0.37. It indicates that about 37% of the phenotype differences in the cresty neck trait across the population can be attributed to genetic variations.
• This finding implies that the rest of the differences are due to environmental or non-heritable factors, such as diet or training routines.
• The genetic correlation between the cresty neck score and other conformational traits varied from -0.06 (height-at-withers) to -0.21 (neck-body junction). Negative correlation suggests that as one trait increases, the other decreases and vice versa.

Conclusion

• This research concludes that cresty neck is a common defect in the Pura Raza Español breed, and its presence is associated with factors like age, sex, coat color, and other conformational traits.
• The study advocates that selective breeding could be beneficial for this breed due to the moderate level of heritability of this condition. Such a recommendation means that by choosing parents with ideal traits, breeders may be able to reduce the occurrence of cresty neck in subsequent generations.