WEANING – CAN WE MAKE IT LESS STRESSFUL?

Sport and pleasure horses are typically artificially weaned at around six months of age. Whether weaning is done abruptly or more gradually, in all cases, this ‘artificial’ weaning occurs when the foal is still closely bonded to his mother.

During this period, weanlings commonly experience increased distress behaviours, including decreased eating and sleeping, reduced play, weight loss, the elevation of stress hormones, increased heart rate, a decline in growth, a decrease in bone density, compromised immune function and a concomitant, increased risk in the incidence of respiratory and gastrointestinal infections. Weaning also leaves foals highly vulnerable to developing stereotypies, like windsucking, weaving and self-mutilation. For this reason, weaning has been described as the most stressful event in a young horse’s life.

The natural condition

In natural conditions, foals gradually transition over to solid food as the mare’s milk composition decreases in fat, protein and calories. This generally occurs somewhere after nine months of age, and by ten months, most foals are spending approximately 60% of their time grazing and suckling minimally. Interestingly, this process is led by the foal, not the mare.

Similarly, in these natural conditions, the close bond between mare and foal is not severed with the cessation of suckling, or in some cases, ever. Research following foals over time has found that foals gradually spend more time away from their mothers but only become fully independent if they leave the herd at sexual maturity (at two to three years of age). Significantly, a study conducted in Icelandic horses living in the natural setting found that even when foals were no long suckling and the next year’s foals were on the ground, weanlings still spent most of their time within one horse length of their mothers. In fact, they showed an equally strong preference for their mothers over other herd members after weaning as they had previously, and although they did find new ‘friends’ as they grew older, their mother was always the preferred partner (Henry et al., 2020).

What makes weaning so stressful?

Experiments looking at whether the withdrawal of the milk or the removal of the mother is more stressful in the weaning process (using udder covers to prevent milk ingestion vs removing the mother altogether as is artificial weaning), clearly demonstrate that the loss of the milk is of little to no significance compared to the loss of contact with the mother. With these clear findings that the nutritional separation is of little relevance compared to the physical separation in terms of stress caused, the reason for removing the foal from the mare ‘because the mare’s milk is no longer nutritionally adequate’ becomes irrelevant. Rather than nutrition dictating the time of weaning, it seems then that to avoid creating stress, we should instead be leaving mother and foal together even after the milk has ‘dried up’.

How can we improve the situation?

There have been a number of graduated approaches to weaning that could make the procedure somewhat less stressful for foals. The most evidence-based of these strategies involves leaving the weanling with an unrelated but familiar adult mare or mares. Interestingly, foals weaned with other foals do not fair well, demonstrating more aggression, abnormal behaviours and higher cortisol levels.

So, what about natural weaning?

Some graduated weaning processes may be better than others, but there is little research following these horses over time, leaving us with a severe lack of knowledge about the long-term effects of artificial weaning.

Today there are various economic and practical reasons for early artificial weaning, including the marketing of foals for sale, optimising the mare’s reproductive efficiency and controlling the foal’s nutritional intake. However, many of these reasons are based more on habits and tradition than science.

Although natural weaning may not be feasible in all settings, we should all consider whether natural weaning is possible in our particular environment. The benefits of natural weaning may well outweigh any potential costs. Firstly, foals learn from their dams, and much of the foal’s early education (handling, boxing, desensitising to novel objects etc.) can be addressed with a calm mother on hand. Natural weaning also puts foals at a greatly reduced risk of developing stereotypies, and we must acknowledge the possibility that happier foals will perform better as adults than foals that have undergone the trauma of artificial weaning.

Final thoughts

Given the compelling evidence of the negative effects of artificial weaning and the clear benefits of natural weaning, it may be time for us to make the shift to make natural weaning the default and artificial weaning an anomaly reserved for certain unique cases. At the very least, we should all be asking ourselves the question, ‘Do I really need to wean this foal?’