Management of dairy heifers: Can operant conditioning be an effective and feasible tool to decrease stress and ease...

Area of Science:

• Animal Science
• Behavioral Science
• Veterinary Medicine

Background:

• Regular growth monitoring in dairy heifers is crucial but challenging due to handling-induced stress.
• Heifers, particularly those responsive to humans, may experience significant stress during restraint and handling procedures.

Purpose of the Study:

• To investigate if operant conditioning training can reduce stress in dairy heifers.
• To assess if training improves ease of handling and reduces farmer effort.
• To evaluate the impact of training on heifers of different ages and responsiveness to humans (RTH).

Main Methods:

• Sixty Holstein heifers (young/old, confident/neutral/nonconfident RTH) were divided into trained and untrained groups.
• Trained heifers underwent 8 sessions of target training with positive reinforcement (feed) for tactile contact.
• Physiological (heart rate, RMSSD, fecal cortisol metabolites) and behavioral stress indicators were measured before and after training.

Main Results:

• All trained heifers successfully completed target training, allowing touch on sensitive areas by the fourth session.
• Trained heifers exhibited higher RMSSD (indicating lower stress) than untrained heifers.
• While training did not affect heart rate, cortisol, or distress behaviors, it reduced avoidance distances in all heifers, suggesting habituation.

Conclusions:

• Operant conditioning effectively reduces physiological stress indicators (vagal tone) in heifers.
• Training enhances handling by reducing heifers' responsiveness to humans, benefiting both animals and farmers.
• Non-associative learning, like habituation, also contributes to reduced human responsiveness in untrained heifers exposed to the training environment.