Inbreeding 
“In general,”’ Mr. Wriedt said, ‘“They 
learn this: that in every breed the 
valuable strains or families are found 
to contain the names of a very few 
ancestors, repeated a great many times. 
In short, that the valuable part of any 
breed is due to a small number of ani- 
mals, usually sires; these sires, which 
we would call prepotent, have been 
used as much as _ possible, through 
inbreeding and linebreeding. 
“The secret of the great successes in 
live stock breeding, then appears to be 
merely that the valuable ‘blood lines’ 
were picked out and conserved through 
inbreeding.” 
“And this inbreeding does not lead 
to disaster?” 
“Not at all, if the animals are good; 
Take for example the famous Kladrub 
breed of horses in Bohemia. It is 
probably the purest breed in the world— 
one of the few breeds of horses that has 
any right to call itself pure. 
THE KLADRUB BREED 
“Its foundation was a Spanish breed 
of heavy carriage horses which had been 
closely bred and kept pure for many 
hundreds of years, when it was taken 
to Austria in the sixteenth century for 
the use of the court. The chief char- 
acteristics of the breed are the Roman 
nose, arched neck, heavy crest, great 
height (17 or 18 hands) and extravagant 
gait. The breed is a very small one, 
rarely consisting of more than a hundred 
individuals, but they are regarded in 
Austria as the finest parade horses in 
the world, and may be used only by the 
royal family and by the Archbishop of 
Olmttz in Moravia. They are ordi- 
narily seen only on great occasions, 
when the emperor drives in state behind 
six or eight of them, all grays or all 
blacks—the only two colors found in the 
breed. As they are all for ‘show’ their 
trotting speed is only a few miles an 
hour—this gives them a chance to 
exhibit their fancy action. 
“New blood is very seldom intro- 
duced into this breed, and because of 
the small number of animals existing, 
inbreeding must have been quite close 
for several centuries. In recent years 
no stronger inbreeding than cousin 
in Europe 205 
matings has been practiced; yet the 
Kladrub horses probably represent in 
their history more inbreeding than any 
living breed. Are they degene rate? 
Not a bit. The only unusual result is 
that it has become very difficult to tell 
when the mares are in heat. But there 
has been no diminution in fertility, nor 
any increase in the number of weak or 
defective animals. They are very slow 
to mature, seldom reaching full size 
before the sixth year; on the other hand, 
they remain vigorous to a_ very 
advanced age. 
“This long-continued example of in- 
breeding shows that if the stock is good 
at the start, inbreeding will fix the type. 
It is a pity that these animals are not 
available for experimental purposes, for 
according to theory they ought to be 
extraordinarily prepotent. It would be 
of great value to find out whether this 
is actually the case when they are mated 
with other breeds. 
“The Percherons offer a great ex- 
ample of inbreeding and prepotency,”’ 
Mr. Wriedt continued. ‘‘Most of the 
good animals today trace back in 
several lines to the two stallions Brillant 
755 and Brillant 756. 
A GREAT PREPOTENT SIRE 
“But the most conspicuous example 
of prepotency which has ever come under 
my own observation is that of the Jut- 
land stallion, Aldrup Munkedal, born 
in Denmark in 1893. He is sire of 
practically all the sires of that very 
valuable and by no means inconsiderable 
breed called the Jutland breed.” 
““And you believe, I suppose, that 
inbreeding increases prepotency?”’ 
“Certainly. Prepotency is simply 
the condition of being purebred— 
homozygous—for a large number of 
dominant characters. 
“Tf we understand that prepotency 
depends on having received the same 
dominant characters from both lines of 
descent, we realize that the surest way 
to produce prepotent animals is by in- 
breeding, where they are certain to get 
some, at least, of the same characters 
from both parents. Occasionally one 
may get an equally prepotent animal 
as the result of a cross, but then it is 
