Study type: Medical/biological study (experimental study)

Exposure of pregnant dairy heifer to magnetic fields at 60 Hz and 30 microT med./bio.

Published in: Bioelectromagnetics 2007; 28 (6): 471-476

Aim of study (acc. to editor)

This in vivo study was performed to investigate the effects of low frequency magnetic field (comparable to this encountered underneath a 735 kV high tension electrical power line) in pregnant heifers concerning hormone concentrations, feed consumption, and body weight.

Background/further details

32 pregnant Holstein heifers (about two years age) were examined in trimester of pregnancy. The heifers were divided into two groups of 16 animals. Each group was divided into two subgroups of eight animals each (one group the non-exposed and the second, the exposed group). The animals were subjected to the different treatments for four weeks. After four weeks, the animals switched treatment, the exposed group becoming the non-exposed group and vice versa.



Exposure Parameters
Exposure 1: 60 Hz
Exposure duration: 20 h/day continuous for 2 x 4 weeks; with a two months intervall without exposure between the experiments

Exposure 1

Main characteristics
Frequency 60 Hz
Exposure duration 20 h/day continuous for 2 x 4 weeks; with a two months intervall without exposure between the experiments
Exposure setup
Exposure source
Chamber chamber: 15 x 10 x 3 m, containing 8 wooden cages, each housing 1 animal
Sham exposure A sham exposure was conducted.
Measurand Value Type Method Mass Remarks
magnetic flux density 30 µT - measured - -

Reference articles

  • Burchard JF et al. (1999): Macro- and trace element concentrations in blood plasma and cerebrospinal fluid of dairy cows exposed to electric and magnetic fields

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • before exposure
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

The exposure of pregnant heifers to magnetic field produced slight physiological effects. This was evidenced by statistically significant higher body weight, higher weekly body weight gain, and decreases in the hormone concentration of prolactin and insulin-like growth factor.
The absence of abnormal clinical signs and the absolute magnitude of the significant changes detected during magnetic field exposure disprove any major animal health hazard.

Study character:

Study funded by

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