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).
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
|
|
| Frequency | 60 Hz |
|---|---|
| Type | |
| Waveform |
|
| 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 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 | - | - |
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.
This website uses cookies to provide you the best browsing experience. By continuing to use this website you accept our use of cookies.
