Modern breeding and management practices generally impose constraints and timelines on weaning foals that don’t exist in a horse’s natural environment. One major aspect is the practice of early artificial weaning. Weaning is not just a stage of diet transition for a foal but also a stage of social separation from the dam. Under domestic conditions, most foals are artificially weaned early, between 4 to 7 months of age. The practice of early artificial weaning leads to short (and in some cases long-term) negative behavioral outcomes for foals. A recent research study observed the natural weaning practices of mares and foals and determined that most foals were weaned spontaneously between 9 and 11 months of age, and overall, natural weaning induced no stress response in either the mare or foal. The study produced several important conclusions for breeders to consider – namely that the practice of early artificial weaning be reconsidered.
During the study, it was observed that natural weaning induces no frustration in the mare (such as dam-directed suckling attempts or non-nutritional sucking of other foals) or distress behaviors in the mare or foal. These results suggest that the main source of stress in early artificial weaning is not the cessation of suckling but rather the abrupt rupture of the dam–foal bond.
This observation explains why gradual artificial weaning (allowing foals to see, hear, smell, and touch their dams through a fence or over a stall wall but not allowing the foal to suckle) results in fewer negative behavioral responses from mares and foals than abrupt artificial weaning. Many studies have previously demonstrated that abrupt early artificial weaning (where mares and foals are completely physically separated from sight, smell, and touch) induces classical behavioral and physiological signs of distress such as vocalizations, running, aggression, higher cortisol concentrations, gastric ulcers, and even injury.
THE MARE AND FOAL BOND
When taken all together, these findings call into question the initial assumption that the primary importance of the mother-foal bond is food-based. In reality, the mare’s role is much more important than providing a source of nutrition. Many breeders list the insufficiency of the mare’s milk supply to meet a growing foal’s energy requirements as one of the primary reasons for early artificial weaning. On the contrary, research has found that early artificial weaning induces a similar reduction in average daily weight gain no matter what age it is carried out.
To date, there is increasing evidence that other aspects relative to the mare-foal bond, such as emotional security or social preferences, are much more important to the development of the foal. This is probably one of the reasons why, outside of rare exceptions, weaning (cessation of suckling) prior to the age of seven months almost never happens in natural environments. In other mammal species, it has been well-documented that once the attachment bond with the mother has been established, young animals exhibit a strong preference to stay near their mothers, even in the absence of a food supply.
Therefore, when deciding when to artificially wean the foal, it seems important not to focus only on the age of the foal and the preparation of the feeding transition but rather to pay more attention to individual variations in the strength of the social bond between the dam and foal. Some foals, even older ones, may be less socially independent and closer to their dams, which may lead to a more intense negative reaction to early artificial weaning. Natural weaning occurs over several months through a gradual increase in the mare–foal distance, a progressive decrease in suckling frequency, an evolution to a more varied diet for the foal, and the development of a larger social network. Interestingly, several studies show that reduced suckling and increased distance behaviors are almost exclusively initiated by the foal, and therefore, the timeline for these behaviors varies based on the foal’s natural disposition and confidence. Some foals stay very close to their mothers, suckle more frequently and interact less with peers than their same-aged counterparts. Research has demonstrated that these individual variations can be related to genetic influences of the dam or sire and even early adverse experiences. Although foals may initiate the weaning process in natural conditions, spontaneous weaning of foals is observed to be primarily initiated by the dams when their foals are about 9 to 11 months old. The close relationship between the mare and her foal continues until the youngster becomes sexually mature and leaves its natal group around the age of 2 – 3 years old.
IMPLEMENTING NATURAL WEANING
In large breeding farms, natural weaning may be more difficult to implement. The mare has often been put in foal for the following season, and breeders are often eager to sell this season’s foals before winter. Early artificial weaning, and often abrupt early artificial weaning, is easy to accomplish and usually does not require additional cost to feed and house nursing mares and their foals for several additional months. However, research indicates that more than 80% of breeders only have 1 – 2 breeding mares. For smaller breeding farms, it’s likely that natural weaning is more feasible from both a cost and management perspective. Maintaining foals with their dams over a longer period offers many benefits to the development of the foal, primarily the use of maternal influences to facilitate the behavioral and social education of the foal.
Reference: Henry S, Sigurjónsdóttir H, Klapper A, Joubert J, Montier G, Hausberger M.
Domestic Foal Weaning: Need for Re-Thinking Breeding Practices?. Animals (Basel).
2020;10(2):361. Published 2020 Feb 23. doi:10.3390/ani10020361