Study type: Medical/biological study (experimental study)

Blood melatonin and prolactin concentrations in dairy cows exposed to 60 Hz electric and magnetic fields during 8 h photoperiods med./bio.

Published in: Bioelectromagnetics 2004; 25 (7): 508-515

Aim of study (acc. to author)

To investigate the effects of 60 Hz electric and magnetic fields on the melatonin and prolactin concentrations in the blood of dairy cows subjected to short photoperiod (8 h light/16 h dark).

Background/further details

Two experiments were conducted. 1st with pregnant, lactating cows; 2nd with nonlactating, nonpregnant cows.



Exposure Parameters
Exposure 1: 60 Hz
Exposure duration: repeated daily exposure, 16 h/day for 4 weeks

Exposure 1

Main characteristics
Frequency 60 Hz
  • unspecified
Exposure duration repeated daily exposure, 16 h/day for 4 weeks
Additional info Experiment 1: Each animal was randomly assigned to one of the two sequences. Each sequence consisted of three exposure periods of 4 weeks. first sequence: OFF/ON/OFF; second sequence: ON/OFF/OFF.
Exposure setup
Exposure source
Chamber Exposure chamber (15 m x 10 m x 3 m ) containing 8 wooden box stalls each holding one cow
Additional info The magnetic field was generated by 14 rectangular coils (10 m long x 4 m high) with the lower part of each coil embedded in the ground. Uniform electric field was generated by two plates (9 m long x 6 m wide) which were suspended from the ceiling by synthetic insulators.
Measurand Value Type Method Mass Remarks
electric field strength 100 V/cm unspecified measured - -
magnetic flux density 30 µT unspecified measured - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

During the light period the melatonin concentrations in experiment 1 were found to be decreased in EMF exposed animals. However, no significant differences were observed in the dark periode. A similar trend was observed in experiment 2.
EMF exposure leads to significantly increased prolactin level in experiment 1.
The results of these experiments suggest that EMF exposure may alter the endocrine response of cows to photoperiod.

Study character:

Study funded by

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