TRANSMITTING ABILITY OF HOLSTEIN-FRIESIAN SIRES 19 
ing the percentage of fat does not always equal the number of tested 
daughters given in the first column. The difference represents the 
number of daughters that had same test as their dams. 
No sire in this list is completely prepotent; that is, no sire has all 
his tested daughters better than their dams in yield of milk, per- 
centage of butterfat, and yield of butterfat. Sire E is the only one 
that increased the milk and butterfat yield of all his tested daughters 
over the yields of their dams, but only four of his daughters had a 
higher percentage of butterfat than their dams. Several sires in- 
creased the milk yield of a great majority of their daughters. For 
example, one sire increased the milk yield of 4 out of 5 daughters; 
another sire increased the milk yield of 11 out of 13 daughters; 
another 10 out of 12 daughters; another 9 out of 11 daughters; and 
another 7 out of 9 daughters. 
Some sires were also prepotent in decreasing the milk yield; for 
example, one sire decreased the milk yield of 5 out of 6 daughters; 
another, 6 out of 7 daughters; another, 11 out of 16; and another, 
4 out of 7 daughters. 
Four sires were prepotent in influencing the percentage of butterfat 
in the milk of their daughters. One sire's daughters had higher 
percentages of butterfat than their dams in every case. On the 
other hand, two sires had 6 out of 7 daughters with lower percentages 
of butterfat than their dams, and another sire had 14 out of 16 daugh- 
ters with lower percentages. 
Only nine sires had a majority of their daughters with higher 
percentages of butterfat than their dams. There were 15 sires that 
had over half their daughters with a larger yield of milk than their 
dams, and 16 sires had over half their daughters with a larger yield 
of butterfat than their dams. 
This study indicates that some sires are capable of increasing in 
the great majority of their daughters both the yield of milk and the 
percentage of butterfat in the milk over that of the dams. Some 
sires may increase the yield of milk in the majority of their daughters 
and decrease the percentage of butterfat. Several sires decreased 
both yield of milk and percentage of butterfat in the milk. Fewer 
sires were prepotent in increasing the percentage of butterfat in 
the milk of their daughters than in increasing the milk yield of 
their daughters. No sire in the list increased both the milk yield 
and the percentage of butterfat in the milk of all his daughters, or 
decreased the milk yield and the butterfat percentage in the milk 
of all his daughters. 
METHOD OF BREEDING AND RECORD OF DAM AS INDICATIONS OF 
A SIRES BREEDING ABILITY 
Table 9 shows the 23 sires listed in the order in which they were 
ranked on the basis of comparative production of milk and butterfat 
of their daughters, as in Table 7. The record of the dam of each 
sire is given first. The next column shows whether the sire was 
inbred, line bred, or outbred; and the last two columns give this 
same information for his sire and his dam. The figures in the last 
three columns refer to the popular expression "common blood/' 
meaning the percentage of common ancestry that appeared on the 
sire's and dam's side of the pedigree in five ancestral generations. 
