FINDING THE PREPOTENT SIRE 
Only Cne in a Thousand, in the Guernsey Breed of Cattle, Is Likely to Bring 
Marked Improvement to the Breed—Advanced Register the Only 
Way of Discovering Him 
J. M. Hover 
Professor of Agriculture, Bethany College, Bethany, W. Va. 
HE superiority of one parent or 
breed in determining the charac- 
teristics of its offspring is termed 
prepotency. The fact that 
marked prepotency occurs in only a 
few animals in every breed makes it 
an important consideration in animal 
breeding. Indeed, nearly all of the 
so-called families in the various breeds, 
and in fact some of the breeds, owe 
their origin to amale or female ancestor 
which was strongly prepotent in fea- 
tures recognizable and useful to man. 
While prepotency is generally thought 
of in connection with some useful char- 
acter, it is not necessarily an advan- 
tageous thing. It is conceivable that 
an animal could be prepotent in a way 
diametrically opposite to the end sought 
by the breeder. In such a case the 
sooner the breeder recognizes and elimi- 
nates such an animal from his herd the 
more quickly will the desired results be 
obtained. In using the term here, 
however, we shall have in mind only 
prepotency in the production of but- 
terfat. 
Inasmuch as the dairy industry must 
rest upon an economic foundation, and 
since heavy production of milk and 
butterfat is the basic factor in profit- 
able dairying, it is just as important, 
and perhaps more important, that the 
sires of “‘boarders’”’ be eliminated in 
cattle breeding as it is to eliminate the 
“boarders”’ themselves. This can best 
be accomplished by the development 
of methods for the recognition of the 
prepotent animals and strains in pro- 
duction in the various breeds and the 
general use of these, both in grading 
and in building up purebred herds. 
The following study of the Guernsey 
breed was made with the idea of dis- 
covering, if possible, those animals and 
strains which have had, and are likely 
in the future to wield, the largest in- 
fluence on the breed so far as higher 
production is concerned. 
Prepotent animals are usually dis- 
covered through the performance of 
their offspring, sometimes long after 
they themselves have died or perhaps 
been slaughtered in the prime of their 
breeding career. Probably discovery 
of prepotent animals will constitute an 
essential feature of breeding in the 
future, but the advanced register, if 
utilized properly, will eliminate in a 
large measure much of the chance 
attendant upon breeding and impres- 
sive sires may be selected with a cer- 
tainty heretofore impossible. There are, 
without a doubt, in the untested stock 
of the country many great producing 
sires and dams, but the progressive 
breeder will scarcely take the risk of 
selecting sires from these, especially 
when they are not related closely to a 
tested strain of proven merit. 
INDIVIDUAL PREPOTENCY 
There are doubtless many ways in 
which the data of the advanced register 
might be used to discover those animals 
which have been most powerful in 
influencing the high production of the 
breed. The common method is to 
regard the number of advanced registry 
offspring as the test. This is open to 
the following criticisms: (1) Some of 
the greatest animals may be used in 
1The data for this paper were secured from the Herd Register and Guernsey Breeders’ 
Journals of the American Guernsey Cattle Club. 
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