Minimising the stress of weaning

What is the least stressful way to wean foals? A small scale pilot study compared three different procedures.

The research was carried out at the Graf Lehndorff Institute for Equine Science, Neustadt (Dosse), Germany, under the direction of Professor Christine Aurich. A full report of the study has been published in the journal Stress.

Different weaning procedures were used for each of three groups of mares and foals. Each group comprised 6 (or 5) mares and foals.

Methods of weaning used were:

• Group A (6 foals): all foals in the group were weaned at the same time

• Group B (5 foals): all foals were weaned at the same time, but were left with two mares with which they were familiar, but not related.

• Group C (6 foals): these foals were weaned by removing two mares from the group on each of three consecutive days

During the weaning process, the researchers monitored the foals' behaviour and movement. They also measured the concentration of cortisol in the foals' saliva, recorded their heart rate and variability, and their weight.

The results confirmed that weaning was associated with stress. All groups showed an increase in salivary cortisol on the day of weaning. In Group C the cortisol concentration remained elvated for two days.

Abrupt weaning with no further contact with adult animals seemed to be the most stressful. Foals in Group A lost weight for two days. They seemed more unsettled - spending more time moving about on the day of weaning. They also showed the most pronounced increase in heart rate.

Foals that were weaned in the presence of two familiar but unrelated mares, (Group B) seemed least affected by the weaning procedure. Of the three groups, they showed the least locomotion and vocalisation after weaning.

The researchers conclude: “Based on cortisol release and behavior, weaning is associated with stress but this was least pronounced in foals weaned in the presence of two familiar but unrelated adult female horses.”