NORMAL ELECTROGRAPHIC AND VECTOCARDIOGRAPHIC DATA IN THE GROWING FRIESIAN CALF USING A SEMI-ORTHOGONAL LEAD SYSTEM

This study derives normal values for electro- and vectocardiographic p arameters, as generated by the Holmes semi-orthogonal lead system, in healthy growing calves. Sixty-four electrocardiograms were recorded fr om healthy Friesian calves aged from one week to one year. Waveform an d duration were analysed and compared in the X-, Y- and Z-leads. The m odal P, QRS and T tridimensional vectors were graphically constructed and their magnitude and orientation were calculated. The duration of w aves and intervals were similar to data previously reported in the bov ine species. Differences from data reported in other species were attr ibuted to heart rate. The duration of waves and QT and ST intervals si gnificantly lengthened with the decrease in heart rate which occurred during growth. PR interval significantly lengthened with physical matu ration, and this change was independent of the decrease in heart rate. The magnitude and the orientation of the spatial modal vectors were a pproximately similar to the few data previously reported in cattle and in other ungulates and were not affected by somatic growth.