Reducing Weaning Stress

Weaning, whether occurring in nature or in a managed system, is evolutionarily designed to be stressful, as it is in the youngster’s best interest to maintain proximity to his mother for protection, comfort, and nourishment. It is also in the mother’s best interest to provide this safe haven to ensure the survival of her offspring, at least until she makes way for the next youngster. Our managed systems have done much to exacerbate this stressful event, putting foals at increased risk for numerous, chronic, and mostly unnecessary physiological and psychological lifelong problems.

Under natural conditions, foals are weaned at anywhere from eight months to a year, usually coinciding with the arrival of the next year’s foal. If the mare did not conceive, the yearling may continue to nurse up until two years old. The integral social bond between the mare and foal does not end abruptly with the cessation of nursing, but persists after the birth of the next offspring until the youngster leaves the herd at three or four years (Waring, 2003).

In managed systems, weaning is abrupt and permanent, contrived by a human handler, and occurs between four and six months of age. It involves a nutritional and social change often accompanied by social isolation, confinement, environmental and social upheaval, increased human intervention, fewer foraging opportunities, and additional changes in feeding and management.

Artificial weaning has been associated with distress behaviours (decreased eating and sleeping, reduced play, increased aggression), elevated stress hormone levels, increased heart rate, decline in growth, decreased bone density, weight loss, and compromised immune function, which in turn make foals more vulnerable to respiratory and GI infections (Erber 2012).

WEANING AND STEREOTYPIES

Weaning also poses a substantial risk for the development of stereotypies – chronic, invariant, ritualistic behaviours that appear to serve no useful purpose (cribbing, weaving, self-mutilation, etc.) Weanlings are at higher risk for the development of stereotypies than any other age group, with the majority of all equine stereotypies developing within one month of weaning. (Nicol 1999).

Stereotypies may well be more purposeful than they appear, as they link in to the body’s natural endorphin system and thus provide a coping mechanism and a modicum of relief in an inescapably stressful environment. Stereotypies are typically lifelong, extraordinarily resistant to modification (even when the weaning stress has subsided), nearly always have negative welfare consequences for the horse, detract from the animal’s value, and often result in such profound behavioural disturbances that the horse is said to be “wasted” (i.e. considered to be of no use and destroyed).

REDUCING WEANING STRESS

Unquestionably, it is in the industry’s best interest to reduce weaning stress where possible in order to avert these negative consequences and potential wastage.

Give Them Space
There is wide consensus from equine practitioners and scientists that 24/7 pasture turnout in a large field with other horses is the “gold standard” for weanlings. René van Weeren, DVM, equine sciences professor at Utrecht University in the Netherlands, notes that many pasture situations are too nutrient-rich and too boring for youngsters. Optimally, pastures should have varied terrain (e.g. woods, hills, bushes, creeks or ponds, and a variety of forage). This environment promotes a healthy musculoskeletal system, with denser bones and stronger, more resistant tendons and ligaments, making youngsters less prone to injury as adults.

Pasture is equally critical for healthy psychological development. Waters and colleagues found that foals housed in stables (whether singly or in groups) were at higher risk of developing stereotypies compared to those kept in groups at grass (Waters et al., 2002; Parker et al., 2008).

Further, pasture turnout allows weaning to occur gradually, where both mare and foal naturally increase the distance and duration of separation as the foal ages. When kept together in stalls, even for only a portion of the day, this gradual increase in distance cannot occur and the abrupt separation at weaning becomes more acute.

Introduce them To Handling
Handling foals early may reduce weaning stress by augmenting the foal’s ability to adapt to new circumstances. Lansade’s research group found that foals handled immediately after weaning were easier to handle and less reactive than foals whose handling had begun only three weeks later (2004). It appears that handling around weaning may be advantageous in strengthening the bond between horse and human at a time when the horse is sadly in need of a friend and short on alternatives.

Hire a Nanny
Weanlings are typically housed with same age and same sex peers after separation, but research indicates that this practice may not be ideal. Although paired or group foals seem to exhibit less separation distress than singly weaned foals, they engage in more aggressive behaviour, introducing yet another stressor to an already stressful situation. Under natural conditions, weanlings would socialize with horses of varied sex, age, and rank.

Henry and colleagues, in a 2012 study of 33 mare and foal pairs, found that foals weaned with their peers along with unrelated and unfamiliar adults exhibited fewer stress-related behaviours at weaning, less aggression, and better social cohesion, as well as lower levels of abnormal behaviours compared to foals weaned with similarly aged peers only. Erber and her research group (2012) found similar benefits for a “nanny group” – where mares were removed at weaning and foals remained with peers and unrelated mares who had been with the foals since birth. The nanny group foals whinnied and paced less, lost less weight, ate and slept more, and had lower physiological measures of stress than groups that were gradually weaned (mares were removed two at a time over several days) or abruptly weaned (mares were removed simultaneously). These researchers suggest that the presence of a calm adult may serve as a role model for lowering arousal and teaching youngsters to spend more time eating and resting, and less time fretting and whinnying.

Graduated Separation
Research is mixed about the benefits of graduated separation for reducing weaning stress. Some researchers have found that mares tend to intensify reunion-related behaviour with each separation and frequent separations seem to sensitize the stress response in the foal and increase cortisol levels, rather than reduce them (Warren, 2008). However, researcher Lea Lansade, PhD, in a study of 34 Welsh pony mare/foal dyads, (2016) found that gradual separation (where mares were placed in an adjacent paddock and able to maintain visual contact – so-called ‘fenceline weaning’) resulted in less whinnying, running, and other stress-related behaviours for foals, compared to abruptly weaned foals. Fenceline weaned mares, although tolerating the short-term separations well, exhibited just as much whinnying and anxiety as the abruptly weaned mares when their offspring were fully weaned and no longer in sight. Providing mares with the option of moving away from the foals into a larger and more inviting enclosure, rather than taking them away, seems to mimic natural weaning, and may reduce stress for both mare and foal.

BUT DO THEY GRIEVE?

Horses whose survival depended upon creating and maintaining cohesive social networks form intimate, and often lifelong, pair bonds. Given their complex social nature and their sophisticated social cognition (the ability to recognize and remember the rank and relationship of each herd member) it is reasonable to presume that horses form attachment relationships with family and specific herd-mates just as we do.

Although their grief upon separation from a loved one may not be as complex or as enduring as ours (it is simply too evolutionarily costly to be consumed with debilitating grief when one has to address the business of surviving), it is likely every bit as poignant, real, and painful. Given horses’ memory for unpleasant events is strikingly (and frustratingly) enduring, it is possible that they feel the pain of loss much longer than we might presume.

Where we must sever these relationships in order to satisfy our equine pursuits, there are certainly ways that we can make this rupture more bearable. Good weanling management boils down to less management – less human intervention, less confinement, less grain, less separation anxiety, and less weaning stress.

MINIMIZING STRESSORS

Weaning stress is often exacerbated because the foal not only loses his mother, but is subject to a myriad of other social and environmental changes (new location, new social group, change in diet, etc.), each of which exponentially compound the distress of separation. By minimizing or eliminating these additional stressors, the weaning transition can become more tolerable.

1. Introduce dry feed prior to weaning

Known as creep feeding, introducing the foal to the diet he will have after weaning minimizes weight loss and eliminates one additional weaning stress. There is debate about the wisdom of feeding grain to weanlings because of its known association with the development of stereotypies. Highly palatable feeds appear to be involved in the relationship between stereotypies and the horse’s production of endogenous opiates, both of which trigger the production of dopamine and seem to exacerbate cribbing. Grain may not be necessary for foals on good-quality pasture or free-choice hay and may be best eliminated. Foals fed grain after weaning have been reported to be four times more likely to become cribbers than those who are not (Waters, 2002).

2. Move the mare, not the foal

In interval weaning, one mare is removed at a time from a herd of mares and foals until the foals are eventually left on their own. Foals thus maintain the security of their familiar peers and their home environment. Removing the mares in pairs (preferably with their preferred social partner) will also reduce the mare’s weaning stress (Nicol, 2005).

3. Wean later

Weaning may be particularly stressful for younger foals. Research suggests that 4.5-month-old foals spend considerably more time with their mothers (approx. 90%) than six-month-old foals (50-75%), and that proximity continues to decrease as the foal ages. Early weaning is often recommended to prevent foals from growing too rapidly (that this is due to the mare’s milk is a dubious claim), or to help a mare who is losing condition. Rather than weaning, mares and foals can easily be separated during a supplemental grain feeding for the mare while the foal receives a daily handling session.

4. Leave the weaning to Mom

Unless the mare is going back into performance, and as long as there are suitable companions for the weanling (essential whether the foal is weaned naturally or artificially), there may be no need for human intervention. The mare will wean her foal before or when the next foal arrives. In a study of breeding farms in North America, Europe, and Australia, natural weaning was associated with a decreased incidence of stereotypies in the foals (Parker et al., 2008). Some have hypothesized that early artificial weaning may disrupt the mare-foal bond during a critical period that adversely affects neurological pathways regulating physiological responses to prolonged stress.