E. P. JANKUS, N. A. STALEY AND G. R. NOREN 
55 
I I I I I I I I I I I I 
Turkey 4742 13 weeks Control 
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0. 
Figure 1. — Semi-orthogonal lead system electrocar- 
diographic (ECG) recording of a control turkey at 
13 weeks of age. Phonocardiogram (PCG) recorded 
with microphone placed over left rib area at the site 
of maximal intensity. Paper speed 200 mm/second. 
at this age have high voltage Rx and Ry waves 
which result in frontal plane QRS axis devia- 
tion and significantly larger mean QRS vector 
strengths. By thirteen weeks the control pat- 
tern shows a slight increase in voltages, while 
the RH groups deviate. 
Some RH turkeys recover spontaneously, evi- 
denced by a transition in the ECG from RH to 
control patterns by 13 weeks of age (Figure 3) . 
The RH-recovered group is distinguished by re- 
duction in the QRSx voltage and conversion of 
the QRSy form to a negative value (Table IV) . 
At this age they have a significantly lower mean 
QRS vector strength- and a mean frontal plane 
QRS axis approaching that of the controls. Five 
of the eight turkeys in this group made the 
ECG transition by the ninth week of age. Sev- 
eral in the recovered group had no measurable 
Ry wave at 13 weeks. 
The RH-live group are RH survivors with es- 
sentially the same ECG pattern seen at four 
weeks, but with slightly lower voltages. Their 
mean QRS vector strength is not significantly 
different from that of the controls of the same 
age. All turkeys of the RH-dead group had RH 
ECG patterns prior to death. 
At four weeks all RH groups had signifi- 
cantly lower mean body weights than the con- 
trols (Table V). However, by 13 weeks, both 
RH-recovered and RH-live groups had body 
weights not significantly different from the con- 
trols. 
DISCUSSION 
Pen mating experience with our experimental 
Flock 2 has yielded the following consecutive 
yearly incidences of RH: 26, 6 and 10.2%. Com- 
parative RH incidences for Flock 1 are : 5, 1.3 and 
0.46% . While the incidence of RH in Flock 1 may 
be higher than the general population, it does 
serve as a control to which Flock 2 may be com- 
pared. Because both flocks have been closed to 
genetic outcrossing, the consistently higher RH 
incidence in Flock 2 suggests inheritability of 
the disease. The high incidence of RH in the 
progeny from some matings, especially hens 
mated to Tom 112, suggests a familial mode of 
inheritance (Tables 11 and III), While the data 
are not conclusive, it appears that the tom may 
Turkey 861 13 weeks Round Heart 
Figure 2. — Electrocardiogram and phonocardiogram 
of round heart diseased turkey. Sa-i summation third 
heart sound. Systolic murmer (M). Same calibration 
as Figure 1. 
