28 
BULLETIN 1372 ? U. S. DEPARTMENT OF AGRICULTURE 
In those daughters where both the milk yield and the percentage of 
butterfat were increased over those of their dams, and in those 
daughters where both the milk yield and the percentage of butterfat 
were lower than those of their dams, there may be said to be evidence 
of a positive correlation between the yield of milk and percentage of 
butterfat. That is, the percentage goes up or down with the yield 
of milk, though whether or not in the same ratio only a correlation 
coefficient would determine. 
On the other hand, in those daughters whose percentage of butter- 
fat increased, but the milk yield decreased, and in those daughters 
whose percentage of butterfat decreased and the milk yield increased, 
there may be said to be evidence of a negative correlation. That is, 
as the milk yield increases the percentage of butterfat decreases, and 
as the milk yield decreases the percentage of butterfat increases. 
Of the 198 daughters of these 23 sires (Table 15), 52 are better than 
their dams in milk yield and as good in percentage of butterfat ; 67 have 
a larger milk yield and a lower percentage of butterfat than their dams ; 
44 have a lower milk yield and either an increased or an equivalent 
percentage of butterfat as compared with their dams; and 35 have 
both a lower milk yield and a lower percentage of butterfat than their 
dams. This would seem to offer fairly good evidence that the milk 
yield and the percentage of butterfat are independent in Holstein- 
Friesian cattle, though the total number of daughters inclined toward 
a negative correlation, 111, is somewhat greater than that of those 
inclined toward a positive correlation, 87. The uniform distribution 
of the daughters of each sire in these several classes would seem to 
indicate that but few of these sires were prepotent in controlling the 
percentage of butterfat. No sire has all his daughters in any one of 
these classes, and only four sires have their daughters in only two 
classes, whereas nine sires have their daughters in all four classes. 
Coefficients of correlation between the daughters of 23 sires and 
their dams, with respect to percentage of butterfat, are given in Table 
16. These indicate the extent to which high or low production in 
the dam is followed by similar production in the daughter. The 
correlation coefficients range from —0.39 for sue N to +0.98 for 
sire H. 
Table 16. — Correlation 
between 
daughters and dams relative to per 
cent of butterfat 
Sire 
Number 
of 
daughters 
Correlation of 
daughters to dams 
Sire 
Number 
of 
daughters 
Correlation of 
daughters to dams 
Coeffi- 
cient 
Probable 
error 
Coeffi- 
cient 
Probable 
error 
A... 
5 
13 
12 
9 
6 
9 
7 
6 
6 
20 
6 
11 
-0.07 
+0.49 
+0.34 
+0.32 
+0.49 
+0.75 
+0.31 
+0.98 
+0.47 
+0.15 
+0. 52 
-0. 001 
±0. 30 
±0. 14 ! 
±0. 17 
±0. 20 : 
±0.21 i 
±0.10 
±0.23 
±0.01 
±0.21 
±0. 15 
±0. 20 
±0. 20 
M 
6 
9 
6 
6 
11 
6 
7 
7 
16 
+0.93 
-0.39 
+0.65 
+0.59 
+0.11 
+0.94 
+0.75 
+0.06 
-0.06 
+0.79 
+0.56 
±0.04 
B 
N__. 
±0.19 
C 
O 
±0.16 
D 
P 
±0.18 
E 
Q 
±0.20 
F- 
R 
±0.03 
G._. 
s 
±0. 11 
H 
T— 
±0.25 
I 
U 
V 
±0.25 
J 
±0.09 
K 
w 
±0.12 
L 
Because the daughters of most of these sires are so few in number, 
allowance should be made in interpreting the coefficients derived. 
