WBFSH Puts Spotlight on Weaning

Veterinary

Health Care

-- as reported in the WBFSH State of the Industry Report 2023

Managing foal weaning has been through a trial-and-error practical approach since breeding horses became domestic. Currently, more scientific research has been undertaken to look into alleviating “weaning stress” by decreasing the potential psychological, physical and nutritional stressors associated with domestic weaning.

By observing and studying feral and semi-natural domesticated herds, scientific-based conclusions can be made to reduce the short- and long-term negative outcomes from weaning. Observed natural weaning occurred between 8-11 months old. There was no induced stress response from either the foal or the mare and there were no clear signs of rejection by dams just before or after weaning.

Artificial Weaning

The origins of early artificial weaning may have arisen from the thought of best optimising the foal's physical development as material milk production decreases sharply by the third month of lactation23 and the nutritional requirements of a 3–4-month-old foal exceeds the level of nutrients available from maternal milk. This practice was widespread in professional breeding farms and followed by nonprofessional breeders. Recently, the reasons for early weaning have followed this practice have altered, and are based around early marketing of foals, switching foals' attention from mother to humans25, management of foals' nutritional intake or optimising mares' reproductive efficiency. Early weaning is associated with many if not all of the following changes: maternal deprivation, social isolation, environmental and social changes, more intense human intervention, abrupt nutritional challenges, and changes in feeding and management practices.

Increased Stress

Although there has not been much research around the effects of weaning on the mares, it has been well documented the levels of stress that artificial weaning causes on foals. Behavioural responses such as increased long-distance whinny calls, increased locomotion which result in associated risks of injury, altered feeding and sleeping patterns, aggressiveness, suspension of play and redirected suckling towards peers. Along with these observed responses there are internal stresses to the foals, elevated stress hormone (glucocorticoid) levels, changes in heart rate and decline in growth rates. Associated risks are decrease in immune response and negative impact on maturation of the gut microbiota. Some research has indicated that early weaning leads to other stereotypic behaviours like crib-biting, wood chewing and locomotor stereotypes. Abnormal oral behaviours may occur prior to weaning but increase following weaning, indicators are that this is due to changes in diet and could be a coping mechanism for increased stomach acidity where there may be stomach discomfort. Locomotive behaviours could be the influence of housing and social environment after weaning, lower incidence has been associated with foals kept on grass. Research has even linked altered learning ability in adult stereotypic horses as compared to normal horses and some have indicated long term detrimental health effects of early weaning.

Natural Weaning

A recent study of a semi-natural herd of Icelandic mares and foals have found that natural weaning takes place gradually over several months with a gradual increase in the mare-foal distance and progressive decrease in suckling frequency with a change to a more varied diet and development of a larger social network. Foals are not weaned before the age of 9-11 months or before the birth of the next foal. The dam-offspring bond remains for a long time after nutritional separation. The ages at weaning vary considerably and can be due to the reproductive status of the mare. Pregnant mares tend to wean their foals on average 3-4 months before the birth of the next foal, non-pregnant mares tend to nurse their foals for a longer time. Previous breeding status of the mare, and the presence of yearling will initiate faster weaning. Also, the availability of food resources and weather conditions and maternal body condition are potential factors. The mare-foal distance and suckling activities are mainly due to the foal's initiatives and there are variations among foals due to more of a closeness to dams rather than peer interaction. The main factor in the age of weaning is the conception rates of the mares, but in this study most of the mares were pregnant again and were in the presence of their foals and yearlings. There was no loss of body condition despite the harsh climatic situations and the absence of good supplements other than hay.

Gradual Weaning

Gradual weaning has been proven to result in fewer behavioural responses than abrupt weaning. Gradual weaning techniques over a period of several weeks does not wholly imitate natural weaning as it does not mimic the natural dynamics of the dam-foal bond, suckling frequency does not decrease before weaning and mare-foal proximity remains stable until and even till after weaning. Gradual weaning techniques that allow the foal to retain olfactory, visual and auditory access to the mare result in less behavioural and physiological stress compared to abrupt weaning. Some research has shown that there is an increase in maternal behaviours if foals are reunited with foals with short term separation techniques.

Responses such as classic behavioural and physiologic signs of stress, foal-to-foal aggression, higher cortisol concentrations, and weight loss, can be mitigated with better weaning techniques. Group weaning is associate with a lower incidence of behavioural indicators of stress, if the animals are thoughtfully grouped together. It has been shown that the importance of artificial weaning lies not in the age of the foal or the preparation of the feeding transition, but by paying attention to the strength of the social bond between mother and foal.

Conclusion

Although more scientific research is required for what constitutes best practice in respect to animal welfare for weaning in the domestic environment, improvements to the management of domestic horses regarding weaning needs to be addressed. Current methods have been shown to lead to short and sometimes long-term severe negative outcomes of domestic horses. More research is needed to understand these long-term impacts of weaning on trainability and later maternal behaviour, and other detrimental effects on the performance horse.

Source: WBFSH State of the Industry Report 2023