Influence of electromagnetic stimulation on secreting oxytocin and milk production in dairy cows under the heat stress

The release of oxytocin (OT) and milk ejection are most important for rapid and complete milk secretion and production. Inhibition of OT release and decrease in milk production has been observed in dairy cows during heat stress. The influence of electromagnetic stimulation (EMS) of whole body on the concentration of OT in the blood and milk yield in Holstein cows during a moderate heat stress has been tested. For the purposes of experiment dairy cows (n=60) in full lactation (150 +/- 50 days) were chosen, with an equal daily production of milk, divided into two equal groups: the experimental group of cows (n=30) and the control group of cows (n=30). Experimental animals were exposed by a unique bio-informational EMS protocol of three weeks' duration. OT concentration, milk production and temperature-humidity index (THI) were measured in the week before EMS exposure, during EMS exposure in the first, second and third weeks of the experiment and in the week after EMS exposure. Cows were exposed to heat stress during experiment (average THI 75-82 in all weeks). The concentration of blood OT was significantly different in the experimental group from the control group (p<0.001). In EMS cows OT concentration was higher in the 2nd and 3rd week of the study and the week after compared to the control group. The effect of the study week was not significant for the secretion of OT in the control group of cows (P>0.05). In control group milk production decrease during experiment, while in the EMS group milk production was stable, so that in EMS group milk production was significantly higher in the 2nd and 3rd week of the study and the week after compared to the control group (p<0.05). Dynamic changes in the concentration of OT and milk produced during the experiment show positive correlation (R-2=0.31; p<0.01), and that relation striving towards zero in control group. EMS can reduce the loss in milk production in cows in conditions of heat stress by stimulation of OT production. This needs further research with rigor experimental protocol.