Methodology
Different harness systems were tested (collars and pack saddles), controlling variables that can influence the results, such as draft work when performing different tasks, load displaced, balance of the load, etc.
Phase one:
Seven different collars were tested using pressure pads. Contact area, median, maximum and peak pressures were obtained for the whole collar and critical points. Eight donkeys pulled 20% and 40% of their body weight, using each collar, under controlled conditions.
This phase was mainly focused on the use of pressure pads, determining the force and pressure distribution beneath different harnessing and packing systems in 8 working donkeys (both static and dynamic tests).
Preliminary trials were performed, using a load cell coupling system (dynamometer), fitted between the equipment used, and the animal. Other preliminary tests included the evaluation of workload effort based on physiological parameters (heart rate using a Holter system), with the main purpose of obtaining more reliable parameters for equids’ performance and welfare; and the use of thermal camera to monitor and evaluate all the contact areas of the harnesses used in this project.
Phase two:
Based on the very promising results obtained during the preliminary trials of the first phase of this project; the researchers moved to the second phase. Controlled, real working operations (logging and agriculture) were performed with working donkeys to a) evaluate the three different collars, b) measure the force exerted by the equids using a swingletree dynamometer and c) evaluate the workload effort based on physiological parameters.
Aims
This research will allow the development of easily transportable kit that allows to evaluate in situ any harness system used in donkeys worldwide, assessing its effectiveness and welfare of the animals, allowing to promote changes based on evidence based scientific knowledge.
Objectives
Phase one:
To test existing models and/or contribute to the development of better and more adapted harness system for working donkeys, by assessing the force and pressure distribution beneath the working harness, while monitoring the general health and welfare of the animals.
Phase two:
Objectives were to:
- Test the performance of different collars, under real working conditions (logging and agriculture): 3 collars used on phase 1 (collar 1, 5 and 6) were selected based on their performance, and tested under controlled real working conditions while performing logging and agriculture tasks.
- Measure the force exerted by the equids: A swingle tree with a dynamometer and data logger was developed, allowing continuous recording of the force exerted by the equids during the work.
- Evaluate the workload effort based on physiological parameters (heart rate using a Holter / polar system, attached to the harness used by the donkeys).
Results
Phase one:
Contact area and pressures vary between collars and effort, with design and expansion capacity of the collars playing a major role. Simple collars designed specifically for donkeys performed well, with full collars designed for horses also having good results. Due to reduced expansion capacity and contact in the critical points, the breast collars were the least effective.
Phase two:
Results from the three different donkeys, over two different trials, each consisting of 60 samples, amounts to 360 data points. Analysis of this data set showed that there is no statistical significance between the data acquired from a set of two different trials performed under the same conditions. There is a 95% confidence interval that both trials are equal and therefore validates the repeatability of the measuring process under field conditions.
Conclusions
Harness design:
Design, appropriate padding and manufacturing materials and adjustment capacity are key features for good collars, and such parameters are of paramount importance in terms of health and welfare for working donkeys.
Load measurement:
The design and development of a novel load-measuring device integrated within a swingletree provides a new solution to the problem of quantifying the load profile of a working donkey’s task. Following development and validation of the device, further trials are needed under different working conditions, which will comprise phase three of the project.
