One of the most stressful times in a horse’s life is weaning, when a foal is separated from his dam and asked to adjust to life on his own. But according to Amanda Adams, PhD, a postdoctoral scholar at the University of Kentucky’s Gluck Equine Research Center, certain types of nutritional support could reduce the stresses and health challenges that weaning places on young horses. She spoke on the topic at the 2011 Alltech International Animal Health and Nutrition Industry Symposium, held May 22-25 in Lexington, Ky.

"Weaning is probably the most stressful event in the horse’s life because they go through maternal separation, environmental changes, diet changes, and management changes," Adams explained, adding that weaning poses a number of physiological challenges on young horses, including:

• Increased heart rate;
• Decreased daily weight gain;
• Increased cortisol (the stress hormone) secretions; and
• Increased susceptibility to respiratory disease (e.g., pneumonia caused by Streptococcus zooepidemicus, Rhodococcus equi, equine herpesvirus-1) and gastrointestinal infections (e.g., diarrhea and Lawsonia intracellularis infections).

Why is this? According to Adams, this is a complex question with no simple answer.

She explained that these challenges could be caused by a decrease in the weanling’s immune system response. With a team from the Gluck Center, Adams observed that after weaning (21 days), and possibly due to the physical and mental stress of the experience, foals’ immune responses decreased, potentially leaving them at risk for health problems. The weanlings’ immune responses were eventually observed to returned to normal, but Adams stated that minimizing weaning-associated stress might help prevent decreased immunity post-weaning