Activity level and performance of weaner pigs exposed to 915 MHz microwave radiation

Abstract

Microwave radiation (MWR) (915 MHz) is considered a possible source of supplementary heat for early-weaned pigs. To determine the behavioural effect of this form of heat on weaner pigs, four trials were carried out in which 64 pigs were exposed to microwave (MW) treatment at 11.4 (MW1) or 6.1 (MW2) mW cm-2 or infrared (IR) radiation at 500 W (IRR), each following a 4-d adaptation period. Pigs exposed to both MW treatments displayed greater (P < 0.05) daily percent resting time compared with IR exposed pigs [86.0 ± 1.6 vs. 82.3 ± 2.5 vs. 79.4 ± 3.7% (mean ± SD) for MW1, MW2 and IRR, respectively]. The increase in resting time was greatest after the first day of treatment and gradually returned to pretreatment levels over the course of the 3-wk experiment. The treatment effect over time was also significant (P < 0.05) between IR and both MW treatments and indicated similar patterns of resting time for the MW treatments. The pattern of resting behaviour for the IR group remained relatively unchanged throughout the experiment. Microwave exposure did not have an effect (P > 0.05) on average daily gain [0.32 ± 0.12 vs. 0.28 ± 0.07 vs. 0.30 ± 0.13 kg day-1 (mean ± SD) for IRR, MW1 and MW2, respectively]. The results indicate that 915 MHz MWR causes a power-level-dependent decrease in activity in weaner pigs. However, MW exposure does not significantly affect performance in weaner pigs.