56 
CARDIAC MODELS 
Table IV. — QRS Amplitude Data From Electrocardiograms of Control and Round Heart (RH) Groups of 
Turkeys at Four and Thirteen Weeks of Age* 
Age 
xvxX JUIVC 
4 Weeks 
Number 
9 
8 
5 
6 
X Lead** 
1 ( 4 to —2) 
10 (13 to 7) 
12 (14 to 9) 
5 (14 to —2) 
Y Lead** 
-7 (—2 to —4) 
5 (12 to —1) 
16 (22 to 5) 
13 (26 to 3) 
Z Lead** 
— 1 ( 0 to —4) 
1 ( 7 to —3) 
0 ( 5 to —5) 
— 1 ( 5 to —9) 
Mean vector strength*** 
7.5 ± 2.8 
12.1 ± 2.9 
20.4 ± 5.5 
16.7 ± 8.8 
Probability __ 
<0.01 
<0.01 
<0.05 
13 Weeks 
Number 
9 
8 
5 
0 
X Lead** 
— 1 ( 2 to —3) 
4 (7 to 2) 
8 ( 10 to 4) 
Y Lead** 
—9 (—5 to —12) 
—2 (3 to —5) 
11 ( 18 to 2) 
Z Lead** 
— 3 ( 0 to —7) 
—4 (0 to —6) 
—4 (—3 to —5) 
Mean vector strength*** 
9.6 ± 3.0 
6.6 ± 1.47 
14.6 ± 6.0 
Probability 
<0.05 
>0.05 
* All values in mm deflection. To convert to millivolts divide by 30. 
** Data are expressed as groups mean, numbers in parenthesis are ranges. 
*** Data are expressed as groups mean ± 1 S.D. 
be more responsible than the hen for the trans- 
mission of, or the susceptibility to, the disease. 
Pedigreeing and sex distribution experiences 
provide an interesting comparison to idiopathic 
cardiomegaly (IC) and EFE in man. Greater 
incidence of RH in the male turkey is consistent 
with IC data reported in Edington's and Jack- 
son's Groups II and HI,'' and in 17 cases re- 
ported by Antia.^<* A sharp contrast is noted, 
however, in the sex incidence of EFE reported 
by Moller et al.,^^ where the male/female sex 
Turkey 5482 RH-Recoverec 
i 5 weeks 7 weeks 
Figure 3. — Semi-orthogonal lead system EGG record- 
ing of a turkey spontaneously "recovering" from 
round heart disease. Paper speed 100 mm/sec. The 
voltages used to compute the mean values in Tables 
4 and 5 for this subject would be: Four weeks: X 
(12), Y (10) and Z (4) ; Thirteen weeks: X (4), Y 
(-3) and Z (0). 
ratio was 0.63:1. Turkey RH male/female sex 
ratios of approximately 2:1 have been consist- 
ent, not only in our experimental flocks, but in 
RH deaths occurring in commercial operations 
as well. When these commercial flocks are fol- 
lowed to the processing plant (at 12 to 26 
weeks of age), those birds with lesions of RH 
again have a sex ratio of 2:1. One interpreta- 
tion of these observations is that hens may be 
better able to recover from the acute phase than 
toms. 
The incidence of RH, as shown in Tables 
I-III, is based upon autopsy and/or EGG find- 
ings. These changes are not commonly manifest 
before 10-14 days of age. It must be noted that 
the percent incidence of RH in Table I is based 
upon all poults hatched. Calculating the inci- 
dence of RH on only those turkeys surviving the 
acute phase would, for example, increase the in- 
cidence for the pen mated Flock 2 turkeys about 
Table V. — Live Body Weights (kg) of Control and 
Round Heart (RH) Groups of Turkeys at Four and 
Thirteen Weeks of Age 
EH 
RH 
Age 
Statistic 
Control 
recovered 
live 
RH dead 
4 wks 
Number 
9 
8 
5 
5 
Mean 
0.69 
0.49 
0.45 
0.51 
±0.13 
±0.05 
±0.04 
±0.06 
Probability .... 
<0.01 
<0.01 
<0.02 
13 wks 
Number 
9 
8 
5 
0 
Mean 
5.34 
4.72 
4.67 
±1.34 
±0.86 
±0.57 
Probability — . 
>0.05 
>0.05 
Data are expressed as groups mean ±1 S.D. 
