# Morphological, Morphometric and Phaneroptic Variations of the Mediterranean Donkey and Tunisian Perspective on Conservation and Breeding

## TL;DR

This study examines the physical diversity of Tunisian donkeys, revealing significant differences in size and appearance, and provides a method to estimate their weight using chest measurements.

## Contribution

A new weight prediction equation based on thoracic circumference and a classification of Tunisian donkeys into three size groups.

## Key findings

- Tunisian donkeys show significant morphometric variation, grouped into small, medium, and large categories.
- Sexual dimorphism was observed in neck circumference measurements between male and female donkeys.
- Thoracic circumference is the most reliable predictor for estimating live weight (R² = 95.4%).

## Abstract

Donkeys are still essential to rural life in Tunisia, where they are used for farming, transport, and daily work. However, little information exists about their physical characteristics and differences between males and females. In this study, 556 healthy donkeys from different regions of Tunisia were measured to understand how their body shape and size vary. The results showed large differences in key body dimensions such as height, chest size, and body length. The analysis revealed three main groups of donkeys: small, medium, and large-sized animals. Female and male donkeys also showed some physical differences, particularly in neck and head measurements. The study developed a sidonemple equation to estimate the live weight of donkeys based on chest size, which can help farmers and veterinarians assess the animals’ condition without using a scale. Overall, these findings highlight the great diversity among Tunisian donkeys and provide useful information for improving their management and conservation.

The domestic donkey (Equus asinus) remains an essential component of agricultural systems worldwide, particularly in rural Tunisia. This study aims to conduct a comprehensive morphological characterization of the Tunisian donkey population, focusing on phaneroptic variation, sexual dimorphism and live weight prediction. A total of 556 clinically healthy donkeys, consisting of 207 males and 349 females, were sampled from various governorates in Tunisia. Descriptive statistics revealed significant variability in withers height (98–147 cm), thoracic circumference (100–165 cm) and body length (86–144 cm). Principal Component Analysis identified coat color and belly pigmentation as major contributors to phaneroptic variation, explaining 69.556% of the total variance. Hierarchical Ascendant Classification further classified the population into three distinct groups, with Group I exhibiting smaller body dimensions, Group II having medium sizes, and Group III consisting of larger donkeys. Sexual dimorphism was detected in neck circumference (females: 64.30 cm vs. males: 61.97 cm; FDR-adjusted p = 0.0468). Regression models for predicting live weight indicated that thoracic circumference was the most reliable single predictor (R2 = 95.4%). Overall, the study documents a wide range of morpho-biometric variation within the Tunisian donkey population and provides practical tools for field-based weight estimation, offering valuable insights for future conservation strategies and management programs.