Source of stray voltage and effect on cow health and performance.

In dairy cows, two distinct and important aspects of the interrelationship between stray voltage problems on the farm and dairy cow productivity can be identified. One is behavioral modification that increases in intensity when currents associated with neutral-to-earth voltages above .7 V find a pathway through the cow. The other is immediate endocrine response. Results of research are less clear on the current necessary for the latter to occur; it may require 8 mA or more. This implies, depending on the pathway and the cow's pathway resistance, that voltage difference between two cow contact points must exceed 3 V. Resistance of different cow pathways range from 350 to 1700 omega. Milk production is more likely to be affected adversely when cows are subjected to shock patterns both intermittent and irregular. Less than 10% of the dairy cow population are thought to perceive any electrical currents upon contact with conductive grounding equipment provided voltages on the farm electrical neutral system remain below .35 V. This paper also identifies various sources of stray voltage problems and discusses appropriate procedures for correction.