Effects of Electric and Magnetic Fields on Nocturnal Melatonin Concentrations in Dairy Cows

Abstract

Sixteen multiparous, pregnant, lactating Holstein cows (weighing 600 +/- 50 kg, at 184.8 +/- 52 d of lactation, and at 101.9 +/- 43 d of gestation) were confined to wooden metabolism cages and exposed to a vertical electric field of 10 kV/m and a uniform horizontal magnetic field of 30 microT. The trial was conducted using a switchback statistical design. Cows were divided into two sequence groups of 8 cows each. One sequence group was exposed for three periods of 28 d each. The electric and magnetic fields were off during the first period, on during the second period, and off during the final period. The second sequence group was exposed for three periods also, but the activity of the fields was reversed (on during the first period, off during the second period, and on during the third period). On d 25 of each exposure period, blood samples were obtained every 0.5 h for 14 h starting at 1700 h to determine melatonin concentration. Nocturnal melatonin concentrations did not show any variation that could be attributed to exposure to electric and magnetic fields.

Exposure of pregnant dairy heifer to magnetic fields at 60 Hz and 30 µT

“…Exposure of pregnant dairy heifers to EF did not affect diurnal MLT. Simultaneous exposure to EMF resulted in increases in PRL and IGF-1 in mature cattle but not in pregnant heifers exposed only to EF [Burchard et al, 1998aRodriguez et al, 2004].…”

Effect of occupational EMF exposure from radar at two different frequency bands on plasma melatonin and serotonin levels

“…enzyme in melatonin synthesis due to magnetic field exposure has also been reported (Selmaoui and Touitou, 1995;Yaga et al, 1993;Lerchl et al, 1990) which may result in serotonin increase (Burchard et al, 1998) and melatonin diminution. In support, the melatonin forming enzyme Hydroxyindole O-methyl transferase (HIOMT) has been documented to be affected too (Henshaw & Reiter, 2005).…”

Environmental and social impacts of electricity utilization: broadening the debate

“…A similar experiment using non-pregnant lactating cows (Burchard et al 2003) also recorded increased feed intake, but was accompanied by decreased milk yield and milk fat content. No significant changes in nocturnal plasma melatonin were noted in 12-h photoperiods (Burchard et al 1998) or in 8-h daylengths (Rodriguez et al 2004), but plasma melatonin levels were slightly lower during the light periods in these exposed animals and plasma prolactin was increased in lactating pregnant cows in short day conditions. The influence of 60-Hz EMF environments on melatonin in laboratory animals could not be confirmed by studies on sheep exposed to high-voltage electricity transmissionline environments (Lee et al 1993.…”