HEREDITY AND SEX 
Many Live-Stock Breeders Believe Disproportionate Sex-Ratios May Be Due to 
Inheritance—Experimental Breeding of Dr. Helen Dean King at 
Wistar Institute Indicates that Such is the Fact in Two 
Strains of Rats 
NDER ordinary conditions, for 
every 100 female calves born 
in a herd of cattle, there will be 
107 male calves, the sex ratio 
being approximately the same as that 
of the human species. 
To a breeder of dairy cattle it is 
obvious that an increase in the propor- 
tion of heifers produced would be 
highly advantageous. On the other 
hand, a large increase in the number of 
bulls born might be disastrous. 
Miss Jessie C. Kursheedt, of New 
York, one of the members of this associa- 
tion, is interested in a herd of registered 
dairy cattle where about 75% of all 
the calves born in recent years have 
been bulls. She was led to think that 
this unfortunate state of affairs might 
be due to something in the heredity of 
the herd sire, and accordingly investi- 
gated his pedigree from that viewpoint. 
It was found that he had at least two 
lines of ancestry in which dispropor- 
tionately large number of male calves 
had been produced. His own sire was 
shown in the herd book to have fathered 
sixteen bulls and seven cows; while 
the sire’s sire had seventeen bulls and 
thirteen cows to his credit. The herd 
sire’s grandsire on the maternal side 
was found from the breed records to 
have sired twenty-three bulls and seven- 
teen heifers. 
While the numbers are small, and 
the herd book records not likely to be 
very accurate on this point, it can at 
least be said that in this pedigree a 
general tendency is shown to produce 
more offspring of one sex than of the 
other. 
Practical breeders have often sus- 
pected that such a condition might 
exist. Hoard’s Dairyman (June 25, 
1915), contains the following letter from 
Herb. E. Sharp of the State of Wash- 
ington: 
“T have developed a strain of Lang- 
shan fowls that are producing over 90% 
females, and the trait is being trans- 
mitted from generation to generation. 
“The earliest records we have of this 
trait were of a hen that produced about 
60% females. She was accidentally 
bred in such a manner that the trait 
gradually became stronger until in the 
seventh generation we have hens pro- 
ducing from 90% to 97% females. 
OTHER CASES IN CATTLE 
“Have found one family of dairy 
cattle containing one world’s record 
cow and her two sisters that have 
dropped twelve male calves and only 
one female. An examination of the 
records of the daughters of their sire, 
by other cows, shows that they too 
have inherited the trait, and are pro- 
ducing from 75% to 90% males. 
“The males of this family, when 
used as herd sires, have transmitted 
this tendency along with other char- 
acteristics of the family, so that a 
preponderance of males is quite notice- 
able among the offspring of several 
herds of high quality stock. 
“Certainly no man can long remain 
in the dairy business with a herd of 
cows whose calves are all bulls; a sire’s 
value must depend entirely upon what 
his daughters produce in milk, butter, 
and calves; and the sire, whose daugh- 
ters drop nothing but male calves, no 
matter what their milk and butter 
records may be, will put his owner out 
of business or compel him to buy a 
complete new herd of cows in a few 
years.” 
‘In 1912, I mated twelve hens to 
one cock bird. He was very vigorous, 
and as he had the entire liberty of 
the yard where they were all con- 
fined, we can safely presume that he 
would find practically all the hens 
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