18 
BULLETIN 1352, IT. S. DEPARTMENT OF AGRICULTURE 
Table 21. — Com-parison of average initial and retest records of Jerseys having 
initial records made at age of 11 years or over (class A and class A A records) 
Number 
of cows 
Average initial 
butterfat record 
made at 11 to 
llj^ years old 
Average reentry records made at 
ages shown in these columns by 
same cows as initial records shown 
in column at left (pounds of butter- 
fat) 
In- 
crease 
due to. 
age 
Portion of re- 
entry record 
due to develop- 
Average 
due to 
develop- 
ment far 
eq 
i-t 
c 
CO 
O 
5 
CO 
o 
CO 
o 
Q 
U3 
o 
2 
o 
SO 
o 
00 
a 
3b" 
i—i 
o 
OC 
OS 
c 
OS 
ment 
this 
group 
2 
Pounds 
395 
430 
Pounds 



-37 
-38 
-28 
-37 
-38 
-38 




Pounds 
35 
4 
37 
9 
-13 
173 
40 
134 
78 
36 
43 
103 

P.ct. 
8.1 
1.0 
7.2 
2.2 
-3.0 
34.0 
8.4 
23.1 
14.9 
6.9 
8.1 
17.5 
0.0 
Per cent 
8 1 
421 
Made at ll 1 ^ to 12 
years old 
3 
417 
1 
512 
Made at 12 to 12^ 
years old 
2 
475 
441 
5 5 
1 
413 
431 
• 
Made at 13 to 133^ 
years old 
1 
482 
364 
476 
1 
509 
13. 1 
1 
479 
Made at 13 ^ to 14 
years old 
1 
483 
483 
579 
19 
1 
523 
Made at 14 to 14^ 
years old 
1 
487 
487 
487 
523 
1 
530 
10.8 
1 
590 
401 
Made at 18 to 18^ 
years old 
1 
401 
0.0 
"T~ 
t 
It is a natural assumption that there is a rather high correlation 
between the initial and reentry records of the same cow or group of 
cows. Tables 23 and 22 give the distribution of the 240 Jerseys 
having initial records made at 2 to 2 }/& years of age and reentry records 
made when 3 to 33^ years old, and of the 106 Guernsey cows having 
initial records made when 2 to 2J^ years old and reentry records 
made at 33^ to 4 years of age. The coefficient of correlation of 
these Jersey records is 0.6318 ±0.0262, and of the Guernseys, 
0.7247 ±0.0311. These two groups were selected because they 
contain the largest number of individuals of all of the groups of 
their respective breeds. 
