The effects of environment change at weaning time

19 Apr 2015

Weaning is a stressful time for both mare and foal. Particularly for the foal, many changes often occur at once; they lose their mother, they have a new diet, they often have a new environment and/or  an introduction with unfamiliar horses leading to a new social hierachy.

Scientists in the Czech Republic hypothesised that if some of these changes could be staggered out over different times, rather than all happening at once, weanlings would be less stressed.

To test this, the researcher followed the weaning of  56 warmblood foals at a stud over two seasons. Each season, half of the foals were weaned from their mothers by immediately relocating them to the stud’s youngstock raising facility, 4km away.

The other half of the foals remained in the same environment – the field and barn where they had lived since they were born, while their mothers were removed to a location out of sound and sight, 2km away. Following this method, the foals did not have a change of environment at the same time that they lost their mother. One week later, the foals were then moved to the new environment, the same youngstock raising facility where the other half of the foals had gone before them. The researchers thought that this staggering of changes would result in these foals showing less signs of stress than their counterparts who were relocated immediately.

However, this was not the case. Stress was measured by rate of weight gain and cortisol levels. Once at the new facility, the foals who had waited a week to be moved showed significant slowing of weight gain compared to the foals who were relocated immediately. Even after the study concluded at 5 months, the slowly relocated weanlings were still significantly behind the quickly relocated weanlings in terms of growth.

The researchers have no idea why this is and recommend further study. In the wild, it is the offspring that move away from the environment they are born in. The parent herd remains in the same territory. Perhaps abrupt relocation mimics natural weaning better, and that is why the abruptly removed animals showed better weight gain.

Interestingly, the slowly relocated foals showed lower cortisol levels both after weaning and after relocation than the abruptly relocated foals, indicating, that at this moment in time, these animals were less stressed. This does not correlate with the longer term stress observation of weight gain patterns and the scientists do not know why this is.

Conclusion – it seems preferable to relocate foals as part of the weaning process, but further study is required in this area.

What are your experiences with weaning? Do you relocate mothers, foals or both? How do you minimise stress?

Reference

Note this article is open access and free for anyone to read.

Dubcová, J., Bartošová, J., & Komárková, M. (2015). Effects of prompt vs. stepwise relocation to a novel environment on foals’ responses to weaning in domestic horses (Equus caballus). Journal of Veterinary Behavior: Clinical Applications and Research.