Arizona state miner., 1926-07-31
SIRE'S DAUGHTERS
INDEX OF VALUE

prepared by the United States Department
of Agriculture.)
A great dairy sire is one whose
daughters have a high yield of milk
and butterfat, high average increase
In milk and butterfat yield over theiI
dams, and a high percentage of their
number better than their dams, says
r. r. Graves of the bureau Of dairy
ing, United States Department of Ag-
riculture. All these things must be
taken into consideration when meas
uring the value of a dairy sire, he
says. No one of them alone offers suf-
ficient evidence of the sire's worth.
In a study of % Holstein- -Friesian
sireS, each having six or more tested
daughters from tested dams, some con-
clusions were arrived at concerning
the hereditary transmission of produc-
ton, says Mr.. Graves. Some of the
sires in the list raised both the milk
yield and the percentage of butterfat
| Of their daughters as compared to
the production of their dams. Some
raised one and lowered the other.
| Some lowered both. But no one sire
raised both the milk and butterfat per
centage of all his daughters, nor did
any one sire lower these records of
all his daughters. In other words,
while the sires evidenced a prepo-
tency for raising or lowering prOduc-
ton, no one sire was completely pre-
potent,
The ability of a sire to raise or
lower the yield of his daughters does
not necessarily have a correlation with
the record of his own dam. Rather,
| the prepotency Of a sire seems to de-
pend upon the combination of. factors
governing the yield Of milk and per-
centage of butterfat that he has in
herited from his parents. If he has
inherited only factors that will deter
| mine high milk yield and high per-
centage of butterfat, he will be pre-
potent in impressing these characters
on his offspring. If he and the dams
with which he is mated have inherit
ed from their parents a mixture of
the factors for both low and high pro-
ductiOn, which is often the case,
variety Of combinations in the differ
ent offspring will follow, and they
will be of varying degrees of produc-
ing ability.
The evidence seems to point to both
parents contributing equally to the
Inheritance governing the milk and
butterfat producing capacity of their
daughters says Mr.. Graves. But II
one parent is homOzygOus or pure
for the, hereditary factors determin-
ing high production and the other par
ent is heterOzygOus, or mixed, in It's
inheritance, then the homOZygOus par
ent will have the greater influence on
the producing capacity of the daugh-
ter; yet their daughter will transmit
to a part Of her progeny the Inherit
ance for low production that she may
receive from her heterozygous parent.
For two heterozygous parents it is to
be expected that the daughters will
show a great range in producing ca
pacity from very poor to very good.
4uC 1dCl lIldL I1lc VI Jul
terfat and the milk yield are inherited
independently, at least within limits,
and that both the sire and the dam
contribute to the inheritance Of their
daughters, governing both milk yield
and percentage of butterfat, indicates
that improvement in yield of butterfat
can be brought about by selection for
Doth milk yield and percentage Of but
terfat.
The big problem Is to locate the
sire that has inherited only the fac
tors determining a high producing ca
pacity. The degree to which he has
inherited these factors can be de-
termined only by testing a large num-
Der of his daughters and comparing
their records with those of their dams.
The increasing number of records
of daughters and their dams becom-
Ing available through the COW testing
associations furnishes a means of cal
culating the comparative worth of a
greater number of sires than has been
possible in the past The % sires
in this study were given comparative
ranking in a new method devised by
Mr.. Graves. Each sire was ranked
in comparison with the others with
respect to milk yield Of his daughters,
average butterfat yield, average in
crease Of milk yield, average increase
Of butterfat, and the percentage of
daughters that were better than their
dams in milk and butterfat yield His |
comparative value was indicated by
the sum of his ranking In the various |
classes.
The complete discussion of this !
study has been published in Depart |
ment Bulletin No 1872, just issued. A 1
copy may be obtained, while the sup
ply lasts, by writing to the United :
States Department of Agriculture
Washington, D. G.