Meta-analysis of stray voltage on dairy cattle

Area of Science:

• Veterinary Medicine
• Animal Science
• Electrical Engineering

Background:

• Dairy cows can be exposed to low-level electrical currents (stray voltage) through contact with grounded equipment.
• Understanding the threshold for cow response is crucial for animal welfare and productivity.

Purpose of the Study:

• To quantitatively assess dairy cow responses to contact current (stray voltage) at 50/60 Hz.
• To determine the minimum exposure level (threshold) at which cows respond behaviorally.
• To identify factors contributing to variability in study results.

Main Methods:

• Systematic literature review of 22 published studies on stray voltage and cow responses.
• Meta-analysis to determine the percentage of cows responding at different current levels.
• Pooled analysis of experimental studies to establish a mean behavioral response threshold.
• Qualitative review of milk production data.

Main Results:

• Statistically significant behavioral responses were observed in cows at 3.0 mA.
• Response probability increased with higher exposure levels.
• The overall weighted mean threshold for the first behavioral response to contact current was 4.0 mA.
• Milk production was not affected by exposure to 3 mA or lower for up to 4 weeks.

Conclusions:

• Dairy cows exhibit measurable behavioral responses to stray voltage at specific current thresholds.
• Exposure pathways and patterns contribute to heterogeneity in study findings.
• Current levels at or below 3 mA do not appear to impact milk production within typical exposure durations.