Veterinary session

Transvaginal oocyte aspiration (also known as ovum pick-up, OPU) is a minimally invasive oocyte collection technique successfully used in cattle today. There is an increasing need in animal breeding to produce large numbers of genetically outstanding, high producing progeny. For this purpose, in vitro embryo production is a great opportunity, but its success depends on obtaining sufficient quantities and quality of oocytes from donor animals, which can be ensured by oocyte pick-up. The equipment and technique for OPU is already based on a well-established protocol in cattle, which, according to the literature, has no adverse consequences and can be repeated several times, but no data on its impact on animal welfare are available.

Our aim was to measure the effect of stress induced by the intervention. To monitor stress, we used different parameters of heart rate variability (HRV), as they reflect the function of the autonomic nervous system and allow us to separately assess the activity of the two branches, the sympathetic and parasympathetic systems. The data for the measurements were recorded using an ECG recorder called Televet 100.

In our research we worked with 4 beef cattle. In the first measurement, we recorded the resting ECG without oocyte aspiration or any manipulation of the animals. After placing the electrodes on the animals, we waited some time for adaptation and then measured the heart signals for about 8-10 minutes. These data were used as a reference. Next time, the beginning of the procedure (electrode application, adaptation time) was the same as in the previous examination, but afterwards transvaginal oocyte aspiration was performed. During the whole study, the animals' ECGs were recorded and the times at which the animals underwent any intervention were noted: epidural anaesthesia, removal faeces from the rectum, cleaning of the vulva and the perineum, insertion of the OPU device into the vagina, puncture(s) and aspiration procedure.

The R-R distances of the animals decreased during the OPU intervention, but they responded differently to the intervention. The more agitated cows were less agitated in the second session and this was associated with changes in SDNN and RMSSD. An individual response was observed, which was also reflected by changes in HRV parameters.