Transient stray voltage: is it detrimental to growth performance, health status and welfare of market pigs?

The effects of transient stray voltage associated with an alternating current were evaluated in growing-finishing pigs from 9 to 22 weeks of age. Seventy-two pigs were assigned to 9 blocks of 8 animals each. In each block, the following treatments were randomly distributed: a constant voltage differential created between the feeder or drinker and the metallic floor (woven wire), at a level of 0 volt plus 2-volt pulses (0 V-2 V), 2 volts plus 3-volt pulses (2 V-5 V), 5 volts plus 3-volt pulses (5 V-8 V), and a control treatment without any voltage differential (0 V-0 V). The constant voltage was applied 24 h per day. The pulses of 3 s duration were in the form of an increase in the amplitude of the constant 60-Hz signal. One pulse appeared every 20, 40 and 100 s during the hour following feed distribution and every 60, 120 and 300 s during the rest of the day. The animals were fed ad libitum and received fresh feed twice per day. Once during the 2-week periods at 9-10, 13-14, 17-18 and 21-22 weeks of age, the behaviour of the pigs was recorded during the hour following the two daily feed distributions. Animal weights and blood samples were taken every 2 weeks, from 9 to 21 weeks of age. No significant effect of transient stray voltage on any of the variables measured for the feeding, drinking, sitting or lying activities was found (p > 0.05). At 9-10 weeks of age, the number of rooting bouts was higher for the 5 V-8 V treatment (p = 0.03) and the number of events of butting the penmate was higher for the 2 V-5 V treatment (p = 0.05). Although the water and feed intake did not differ between treatments (p > or = 0.39), the average daily gain of the control group was lower than that of treated groups (p = 0.04) at 9 and 10 weeks of age, while the pigs submitted to a 2 V-5 V treatment had a higher daily gain than the pigs in the other treatment groups (p = 0.05) at 17 and 18 weeks of age.(ABSTRACT TRUNCATED AT 400 WORDS)