# Physiological Auricular and Cornual Asymmetries of the Sanmartinero Creole Bovine

## TL;DR

This study examines ear and horn asymmetries in Sanmartinero cattle to understand how their environment affects development.

## Contribution

The paper reports novel findings on fluctuating asymmetry in ear and horn measurements of Sanmartinero cattle.

## Key findings

- Fluctuating asymmetry was biased to the left for ear and horn length.
- Fluctuating asymmetry was biased to the right for ear width and horn perimeter.
- The asymmetry may reflect developmental instability due to environmental stress.

## Abstract

The Sanmartinero creole bovine (SM) is found in the department of Meta (Colombian Orinoquia) and derives from the bullfighting cattle introduced by the Spanish in the 15th century. Its adaptation process has allowed it to develop adaptive characteristics to live in extreme climatic environments. Although there are studies on its reproductive and productive characteristics, little is known about possible asymmetries in some biological structures. Fluctuating asymmetry allows us to detect a possible developmental instability that may be caused by stressful conditions. The aim of our study was to present the current state of developmental instability in two bilateral cephalic characters of the SM creole bovine. The results showed a fluctuating asymmetry biased to the left for ear and horn length, and to the right for ear width and horn perimeter. We consider that the environment in which it lives may have an impact on the development of cephalic structures, creating stress in the animal, which causes the detected asymmetry. However, the authors are not aware of any studies on this topic.

Asymmetric studies can indicate disturbances in the developmental process. Fluctuating asymmetry (FA) is considered an indicator of stress. The Sanmartinero (SM) creole bovine is native to the department of Meta (Colombian Orinoquia) and its adaptation process has allowed it to live in extreme tropical environments. The aim of this cross-sectional and descriptive study was to present the current state of the knowledge of asymmetries in some cephalic characters of the SM creole bovine. A total of 94 animals were studied (18 uncastrated males and 76 females) from three different farms, with an age range of 0.5–10 years. For each animal, two measurements of the ear (width and length) and two measurements of the horn (perimeter and length) were obtained in vivo. The degree of asymmetry was calculated as (R − L)/(R + L). Bilateral differences pointed towards a fluctuating asymmetry (e.g., a random variation in the trait that is expected to be perfectly symmetrical) biased towards right for ear width and horn perimeter, and towards left for ear and horn length. Since the development of these structures—ears and horns—is under the control of the same set of genes, the fluctuating asymmetry could constitute a reflection of a normal condition.