30 
BULLETIN 1372, U. S. DEPARTMENT OF AGRICULTURE 
The daughters of sire N show stronger indications of a negative 
correlation with respect to percentage of butterf at between daughters 
and dams than the daughters of any other sire. To some extent this 
is also true of his daughters with respect to their milk yield and 
butterfat yield, as stated before. The comparative percentages of 
butterfat of his daughters and their dams are shown in Table 20. 
Table 20. — Percentage of butterfat of daughters of sire N and their dams, indicating 
negative correlation 
Sire 
Daugh- 
ters 
Dams j 
Sire 
Daugh- 
ters 
Darns 
Sire 
1 
Dr.ugh- -^ 
ters Dams 
N 
Per cent 
3.87 
3.78 
3.77 
Per cent | 
3.81 j 
3.54 i 
3.55 ; 
N 
Per cent 
3.75 
3.71 
3. 43 
Per cent 
4.41 
3.71 
3.94 
N 
Percent Percent 
3. 40 3. 54 
3,38 ; 4.32 
3.33 i 4.41 
It will be observed that, in general, the higher-testing daughters 
of sire N come from the lower-testing dams and the lower-testing 
daughters from the higher-testing dams. 
WHICH PARENT HAS THE GREATER INFLUENCE ON THE PERCENTAGE OF 
BUTTERFAT? 
There are a larger number of significant correlation coefficients 
between dams and daughters with respect to percentage of butterfat 
than with respect to fat yield. As explained under fat yield, it is 
doubtful to what extent a significant correlation indicates dependence 
on either parent, because of the lack of homozygosity of the parents 
for yield or percentage of fat. There are other indications than the 
correlation coefficient showing that the dams do contribute to the 
daughters' inheritance for percentage of fat. A study was made of 
all dams to which these sires were mated that had extremes of per- 
centage of butterfat of 3.3 or below, and 3.8 or above, and the per- 
centage of butterfat of the daughters of the dams in these two classes. 
There were 57 dam-daughter pairs, representing 19 sires, in the class 
for dams having 3.3 per cent butterlat or less. The average per- 
centage of fat for these 57 dams and daughters was 3.155 for the 
dams and 3.314 for their daughters. There were 33 dam-daughter 
pairs representing 13 sires in the class for dams having 3.8 per cent 
or over. The average percentage of fat for these 33 dams and 
daughters was 3.966 for the dams and 3.633 for the daughters. This 
would seem to show that the dams do contribute to the inheritance 
for the percentage of fat of their daughters. It further shows, as 
does Table 15, that the sires also contribute to the inheritance of 
their daughters for percentage of fat. 
The tables giving the production records of the daughters of each 
sire and their dams have seemed to show that the daughters' percent- 
age of fat follows that of the dams fairly closely. This might be due 
to the following reasons : 
(1) There may be less variability in the percentage of fat than in 
the milk yield. 
(2) The inheritance for percentage of fat may be better fixed 
(purer) than is the inheritance for the milk yield. 
