60 
GENETICS: PEARL AND PATTERSON 
Jersey Cattle Club. These animals were divided into four series as 
follows: (a) a random sample of the general population of males, (b) 
a random sample of the general population of females, (c) a selected 
sample of Register of Merit males, so chosen as to include the leading 
bulls in the recent history of the breed, these being bulls whose daughters 
were conspicuously excellent producers of milk and butter fat, (d) a 
selected sample of Register of Merit females so chosen as to include 
all of the cows which have recently made world's records in respect of 
butter fat production. 
For reasons which cannot be gone into here, but will be presented in 
the detailed publication, it is impossible in the case of cattle to arrive 
at an absolutely exact value of the mean inbreeding coefficients. What 
we can do is to determine upper and lower limiting values, between which 
the true, and undeterminable value Hes. Such upper and lower hmiting 
values are presented in the table. 
Table Showing Mean Coefficients of Inbreeding for American Jersey Cattle, for Both Random 
Samples of the General Population of Both Sexes and Samples of the Animals in the Register 
of Merit. 
CLASS OR GROUP 
NO. OF 
PEDI- 
GREES 
IN- 
CLUDED 
IN 
SAMPLE 
MEAN COEFFICIENTS OF INBREEDING 
Zo Parents 
Zi Grandparents 
Z2 Great- 
grandparents 
Zi Great-great- 
grandparents 
Lower 
limit 
Upper 
limit 
Lower 
limit 
Upper 
limit 
Lower 
limit 
Upper 
limit 
Lower 
limit 
Upper 
limit 
1. 
General population 
(random sample) 
bulls 
67 
0 
0 
1.87 
1.87 
5.41 
5.41 
11.01 
11.21 
2. 
Register of Merit bulls 
63 
0 
0 
1.59 
1.59 
5.36 
5.62 
14.88 
15.91 
3. 
General population 
(random sample) 
cows 
61 
0 
0 
4.10 
4.10 
6.97 
6.97 
12.50 
12.59 
4. 
Register of Merit cows 
63 
0 
0 
0 
0 
2.98 
2.98 
9.23 
9.42 
CLASS OR GROUP 
NO. OF 
PEDI- 
GREES 
IN- 
CLUDED 
IN 
SAMPLE 
MEAN COEFFICIENTS OF INBREEDING 
Z4 Great-great- 
great grand- 
parents 
Zb (Great)* 
grandparents 
Ze (Great) 6 
grandparents 
Z^ (Great)* 
grandparents 
Lower 
limit 
Upp«r 
limit 
Lower 
limit 
Upper 
limit 
Lower 
limit 
Upper 
limit 
Lower 
limit 
Upper 
limit 
1. 
General population 
(random sample) 
bulls 
67 
19.59 
20.79 
29.48 
32.77 
39.14 
47.93 
46.07 
63.12 
2. 
Register of Merit bulls 
63 
23.32 
28.39 
30.28 
43.99 
34.80 
62.03 
37.07 
77.77 
3. 
General population 
(random sample) 
cows 
61 
21.26 
21.89 
31.53 
33.82 
41.03 
48.18 
47.56 
63.10 
4. 
Register of Merit cows 
63 
15.33 
16.27 
24.63 
28.53 
33.12 
44.06 
39.22 
61.45 
