Variations in heart activity in rams caused by service

Abstract

The aim of this study was to determine variations in cardiac electric activity induced by the service in Churra bred rams using the electrocardiogram. Electrocardiograms (ECG) were performed in five fertile 3 to 5 year-old rams. Three electrocardiograms were obtained from each ram: a) without sexual stimulation (basal registration), b) during service and c) five minutes after service. The EKGs were performed in D I, II and III, using a 3 channel portable electrocargiograph (Hellige, mod. EK 53i), with wax-coated paper at a speed of 25 mm/seg, sensitivity level 1 cm=1 mV. Alligator clip electrodes with hypodermic needles were used for for the attachment to the skin. Classic ventral position of electrodes placement were used. An adult in oestrus ewe was introduced in the paddock in order to obtain the second recording (service). A significant increase in heart rate (p<0.05) and a decrease in the RR interval and TP segment (p<0.05) were observed at service when compared with basal registration. All values returned to baseline (rest), five minutes after service. Duration and amplitude of P, QRS and T waves showed no significant differences. We conclude that service in the ram leads to a tachycardia that would involve a nervous reflex because the rapid installation.