Study type: Medical/biological study (experimental study)

Progesterone concentrations during estrous cycle of dairy cows exposed to electric and magnetic fields. med./bio.

Published in: Bioelectromagnetics 1998; 19 (7): 438-443

Aim of study (acc. to author)

To study the effects of electromagnetic fields on blood progesterone concentrations during estrous cycles in nonpregnant lactating dairy cattle exposed to maximal, continous, and uniform 60 Hz AC electromagnetic fields similar to those generated by 735 kV power lines.

Background/further details

16 cows were divided into two groups and exposed to electromagnetic fields. The length of each exposure period (21 to 27 days) varied according to the estrous cycle length. One group was exposed for three estrous cycles: During the first estrous cycle the electric and magnetic fields were off, during the second estrous cycle they were on, and during the third one they were off.
The second group was also exposed for three estrous cycles, but the exposure was reversed (first estrous cycle "on"; second estrous cycle "off"; third estrous cycle "on").
There was a 12:12 h light:dark cycle. Estrous cycles were synchronized with dinoprost-tromethamine injections.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 60 Hz
Exposure duration: Two exposure sequences with each exposure period based on 21 to 27 days of estrous cycle; 1 and 2 sequences consisted of on/off/on and off/on/off exposure periods

Exposure 1

Main characteristics
Frequency 60 Hz
Type
Waveform
Exposure duration Two exposure sequences with each exposure period based on 21 to 27 days of estrous cycle; 1 and 2 sequences consisted of on/off/on and off/on/off exposure periods
Additional info Vertical electric field and horizontal magnetic field
Exposure setup
Exposure source
  • 14 coils for MF and plates for EF generation
Chamber Wooden metabolic cages
Setup Coils (10 m long x 4 m high) generated uniform MF in the chamber. EF was generated by two plates (9 m long x 6.5 m wide) suspended 0.4 m from the ceiling by synthetic isolators.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 30 µT unspecified unspecified - -
electric field strength 10 kV/cm unspecified unspecified - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

No differences were found in plasma progesterone concentrations and area under the progesterone curve during estrous cycles between non-exposed and exposed periods. However, estrous cycle length was shorter in non-exposed cows than when they were exposed to electromagnetic fields.

Study character:

Study funded by

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