54 CARDIAC 
weeks, and a grower ration from the same 
source to 13 weeks of age. Control and RH tur- 
keys were weighed and ECG monitored at 4, 5, 
7, 9 and 13 weeks of age. At the end of this ex- 
periment (13 weeks) all surviving turkeys were 
sacrificed and autopsied. Based upon ECG and 
autopsy results, the turkeys were grouped into 
control, RH-recovered, RH-live and RH-dead 
groups. The RH-dead group is composed of 
those poults dying prior to the termination of 
the experiment, and having ECG records and 
gross lesions of RH on autopsy. The probability 
values in Tables IV and V were calculated by 
Student's "t" and two-tailed distribution. « All 
ECG and phonocardiographic recordings were 
made with a Sanborn 550 recorder. 
RESULTS 
Breeding Trials 
Flock 1 had higher fertility and hatchability, 
as well as lower poult mortality and incidence 
of RH (Table I). In all groups the greatest 
number of poult deaths occurred during the 
first two weeks after hatching. Incidence of RH 
was greater in both pen mated and pedigreed 
turkeys from Flock 2. In all groups the RH 
male/female ratio was greater than one. 
Incidence of RH in progeny from the pedi- 
greed hens of Flock 2 ranged from 22 % to zero 
(Table II). RH progeny from two hens showed 
ventricular septal defects (VSD). Both hens 
were mated to Tom 112. Percentage of progeny 
Table I. — Performance of Experimental Breeding 
Flocks— 1971 
Flock 1 Flock 2 
Pen mated Pen mated Pedigreed 
Infertility (percent) 10.6 23.6 22.8 
Hatchability (percent) 81.5 82.7 70.0 
Mortality through 35 days 
of age (percent) 22.1 52.3 79.2 
Percent of total 35 day 
mortality during first 
14 days of life 70.0 86.8 90.0 
Total poults hatched 275 394 249 
Round Heart (RH) 4 40* 18** 
RH male/female ratio 4/0 26/14 12/6 
Percent RH 0.46 10.2 7.2 
MODELS j 
I 
I 
Table II. — Incidence of Round Heart in Poults from 
Flock 2, Pedigreed: Hen Performance — 1971 I 
Hen 
No. 
Total poults 
Total RH 
Tom RH 
Hen RH 
€rc cut 
RH* 
127 
12 
0 
— 
— 
0 
128 
10 
0 
— 
— 
0 
129 
. 18 
1 
— 
— 
6 
130 
. 6 
0 
— 
— 
0 
144 
12 
0 
— 
— 
0 
154 
36 
1 
1 
— 
3 
166 
. 1 
0 
— 
— 
0 
157 
. 23 
1 
1 
— 
4 
158 
10 
2 
2 
20 
159 
0 
0 
0 
161 
15 
2** 
2** 
13 
162 
13 
1 
1 
8 
163 
. 4 
0 
0 
164 
32 
7** 
5** 
2 
22 
167 
25 
0 
0 
168 
. 33 
6 
3 
2 
15 
Total 
. 249 
18*** 
12*** 
6 
7.2%* 
* To the nearest percent 
•* One each VSD 
**♦ Not including VSD cases 
with RH from each pedigreed tom ranged from 
19% to zero (Table III). 
Clinical Course of Turkey RH 
During the Chronic Phase 
Identifying ECG features of RH, notably the 
higher voltage Rx and Rt, are shown in Figure 
2 as contrasted with the control ECG (Figure 
1). The phonocardiogram (PCG) of this RH 
turkey (Figure 2) shows a pansystolic murmur, 
and a third heart sound (S3.4) which may be a 
summation of S3 and S4. 
At four weeks, the control group has low X 
lead QRS voltages, while the Y lead voltages of 
— 7 reflect the QS or S wave dominance of this 
lead's QRS complex (Table IV). All RH groups 
Table III. — Incidence of Round Heart in Poults from 
Flock 2, Pedigreed: Tom Performance — 1971 
Tom 
Total 
Total 
Tom 
Hen 
% 
Poults 
RH 
RH 
RH 
RH* 
Hens Mated to Tom 
112 
.. 57 
11** 
9** 
2 
19 
158, 161, 164 
126 .... 
. 37 
5 
3 
2 
14 
159, 163, 168 
117 _.. 
.. 37 
2 
1 
1 
5 
156, 157, 162 
52 
30 
1 
0 
1 
3 
127. 129 
118 
73 
1 
1 
0 
1 
144, 154, 167 
171 .... 
. 15 
0 
0 
0 
0 
128, 130 
Total 
. 249 
18*** 
12*** 
6 
7.2%*** 
• Does not include 3 RH with VSD 
** Does not include 2 RH -with VSD 
* To the nearest percent 
** Two with VSD 
*** Not including VSD cases 
