Effect of electromagnetic field during intramaternal development on habituation of young cattle

We used 22 animals in our experiments, 10 of them created an experimental group and 12 a control one. Mothers of animals in the experimental group were influenced by an electromagnetic field of low intensity from 196th to 258th day of pregnancy. The magnetic induction represented values from 15.0 micro T to 42.1 micro T in the area of cows. Mothers of animals in the control group were in region with zero magnetic field. At the age 12 months were all animals subjected to six 10 minutes open-field tests in three successive days, two tests in one day. The animals were subjected to isolation and silence during the two first tests, a man sitting at the wall was present in the third and fourth test. We applied noise as stress, it was a clear tune produced by tunegenerator with the level of accustic pressure 110 dB and frequency 1000 Hz during the last two tests. We noticed crossing the grids, frequency of motion, vocal and elimination behaviour during the tests. The differences between the groups in number of grid crossings were nonsignificant with the exception of first two minutes of the first test in which was higher activity noticed in the control group. We noticed also higher mean values of vocal expressions in the control group during first two minutes in the course of three days of tests. From the above mentioned facts the conclusion can be drawn that the animals in the control group reacted more quickly to the stress factors. It can be assumed that the effect of the electromagnetic field during the intramaternal development made itself felt in the decreased excitableness of animals in the experimental group. The presence of man in the arena did not make itself felt as a stress factor during the second day of tests. During the fifth and sixth day of tests noise of the intensiveness 100 dB was applied. We noticed increased number of grid crossings in the control group whereas the number of grid crossings rose only little in the experimental group. We noticed higher number of defecation manifestations in the experimental group during the third day of tests. The conclusion can be drawn that the animals in the control group try to compensate the stress situation caused by noise by means of greater motoric activity. The animals which were influenced by the electromagnetic field during the intramaternal development can perhaps engage metabolic mechanisms to eliminate the stress. The effect of noise did not manifest itself in the average number of vocal expressions in either of the groups, the mean values were lower than during the two proceeding days of tests