Herd-level variables associated with delayed milk ejection in Michigan dairy herds

Area of Science:

• Animal Science
• Dairy Science
• Veterinary Medicine

Background:

• Delayed milk ejection, also known as bimodal milk let-down, can negatively impact milk production and udder health in dairy cows.
• Understanding herd-level factors influencing milk let-down is crucial for optimizing milking practices and cow welfare.

Purpose of the Study:

• To identify herd-level variables associated with delayed milk ejection in Michigan dairy herds.
• To investigate the relationship between milking management, cow stimulation, and milk flow dynamics.

Main Methods:

• Observed milking protocols and used digital vacuum recorders to estimate milk flow dynamics in 64 Michigan dairy herds.
• Administered producer surveys to assess mastitis management and attitudes.
• Utilized backward multivariable analysis to identify associations between 47 herd-level variables and delayed milk ejection.

Main Results:

• Delayed milk ejection affected an average of 25% of cows per herd.
• The proportion of cows with delayed milk ejection was negatively associated with mean total tactile stimulation time during premilking.
• Delayed milk ejection was positively associated with larger herd size.

Conclusions:

• Sufficient tactile stimulation during premilking is essential for promoting timely milk let-down.
• Larger herd sizes may present challenges in providing adequate stimulation, potentially leading to increased instances of delayed milk ejection.
• These findings suggest that adjustments to premilking routines could mitigate delayed milk ejection in commercial dairy settings.