In both sport and alternative agriculture, horses are once again being used as draught animals. Efficient power transmission plays an important role in the wellbeing of draught horses.
According to the Food and Agriculture Organisation of the United Nations (FAO), animal traction power is used on 26% of agricultural land in industrialised countries and on 52% in developing countries. With the use of horses on farms, questions arise about the health and welfare of the animals. Evaluation systems have been developed for these issues. It is known that healthy working animals with good welfare contribute more sustainably to their owners’ livelihoods than working animals with low health and welfare status. For draught animals, efficient power transmission leads to better welfare because the animals tire less quickly.
The aim of this study was to classify the performance of working horses with regard to their physical and mental stress. Two defined tractive forces (1300 N and 2600 N = reference values) were continuously recorded as two two-horse teams of Freibergers drew a loaded brake wagon (title photo) for thirty continuous minutes of exertion and the work performed by the horses was assessed.
Performance check on two Freiberger teams
Four Freiberger horses regularly used for agricultural work were used for the work assignment. The first team (team 1/2) consisted of the two mares Hamira (8 years, 560 kg bw) and Laiana (6 years, 600 kg bw), the second team (team 3/4) of the gelding Quinto (11 years, 550 kg bw) and the mare Gana (16 years, 600 kg bw). The tractive force (N) was measured continuously via a tractive force sensor on the wagon (Fig. 1) and the speed (m/s) via GPS and recorded with a computer. The heart rates of the horses were continuously measured with pulse monitors and subsequently evaluated (Polar, V800, Fig. 2). After the end of the respective draught performances, the recovery heart rates were also determined. Blood samples were taken before, during and after work (0, 15, 30 and 60 minutes) and cortisol, glucose and free fatty acids (FFS) were analysed to assess the stress including a possible psychological component.
- The average tractive forces recorded corresponded satisfactorily to the reference values (1300 N and 2600 N), with the actual average value at the first load stage for team 1/2 being 1148 N (reference 1300 N) and 2543 N (reference 2600 N). For team 3/4, the actual average value was 1246 N (1300 N reference) and 2538 N (2600 N reference).
- For both tractive forces and for both teams, the average rounded speed was between 5 and 6 km/h.
- The tractive forces and speeds resulted in tractive powers per horse of 813 and 2095 watts (1.11 and 2.85 hp) for team 1/2 and 919 and 1934 watts (1.25 and 2.63 hp) per horse for team 3/4.
- The heart rates recorded indicated medium to high work intensities.
- Significant correlations were found between heart rate and blood cortisol concentration (mmol/l) (r = 0.64, p < 0.05) and between heart rate and blood FFS concentration (mmol/l) (r = 0.53, p < 0.05).
- The continuous recording of the tractive force of 1300 N and 2600 N with the dynamometer in two Freiberger teams, in combination with heart rate measurement and the collection of cortisol, FFS and glucose values in the blood, allowed the performance to be classified in terms of its physical and mental stress.
- Since heart rates and cortisol or FFS values were positively correlated, a balanced activation of the adrenergic system* and the HPA (hypothalamic-pituitary-adrenal) axis is assumed and therefore a psychological stress component deemed unlikely.
- Lower cortisol increases during exertion in the older team indicate that experience and training reduce possible psychological stress situations.
*Adrenergic system: All nerve cells whose messengers are noradrenaline or adrenaline.