Daily Kennebec journal. [microfilm reel] (Augusta, Me.) 1870-1975, 1913-01-27
eREECElG FOR HIGH PRoDUc-
TON.
Laws of Inheritance of Egg Produc
ton and Their Relation to Breeding
for Milk Production.


For many years past the Maine Ag-
rieultural Experiment Station has been
inYestiga ting the laws of inheritance
of egg production in poultry with a
view to learning how this quality may
be improved by breeding A thor
ough ANALYSIS of the egg production
problem has led to certain definite
conclusions. Briefly stated the fact is
this Every bird has plenty of eggs
inside of her body. and there is a COM
pick physiological mechanism to get
them out. It is in respect to the me-
chanfsm of getting the eggs out of
the body that hens differ. In analyZ-
ing this side of the question, it APP
pears that there must be at least two
entirely distinct factors involved All
birds are endowed with the ability to
produce enough eggs to perpetuate the
species. In poultry even the poorest
laying birds. such as the Crested POI
lish and fowls of the game breeds. per-
haps the poorest of all, will lay
enough eggs in a year to hatch a few
chickens. They will lay as many eggs
at least as The wild jungle fowl which
is the progenitor of our domestic
fowl. The jungle fowl, under condi-
tons of domestication, may lay from
Is eggs to 10 or so in year
Apparently all fowls carry this basic
or first physiological factor Just dis
cussed. But something more than that
is necessary to get high production
Here there is an excess production over
the common run. Evidently this ex-
cess production, since some hens have
it and others lack it, must depend up
on still another, a second physiologi-
cal factor. BY means of records of
production ii has been possible to ana
lyze the mode of inheritance of these
two physiological factors. The key to
the whole situation is in the fact that
the excess production factor, the fac
tor upon which high LAYING records de-
pend, is never transmitted from a fe-
male to her daughters, but only TO her
sons. This gives the clue for the ex-
PLANTATION of all of our results. II
shows that the very high production
records. which have been alternately
the delight and despair of the breeder.
are only made possible by using the
right kind of male as a sire. Any char
acter which is inherited in this way is
known, technically, as q sex linked
character. because the female can only
transmit it to an individual of the op-
posite sex. Now. if what has been
stated is true, if this excess produc-
ton factor is only transmitted from
the females to their sons, it is obvious
that if one can get a male birl which
carries this hereditary physiological
factor in pure form, his daughters
ought to be good layers regardless of
the female with which he is mated.
Such IS, in fact the case. If one mates
male bird which carries this excess
production factor in pure form with
any sort of female, even a very poor
layer. all the daughters prove to be
good layers if properly housed and fed.
In such cases it is obvious that the
egg record of the mother has nothing
whatever to do with the egg records
of the daughters. The result, so far
as concerns the female progeny, all
depends on the male with which the
mother is mated: if he carries the OK
cess production factor IN pure form his
daughters will be good layers. and If
he lacks it, his daughters will be poor
layers
A great deal of attention has been
paid TO breeding dairy cattle for in
creased milk production. The medi-
um through which this has chiefly
been done is the system of advanced
registry" Now there is a fundamen-
tai difference in principle in the meth
cd by which cows are put into the
advanced registry, and that BY which
bulls are entered. A COW is put into
the advapced registry if she is a high
mixer; her production. in itself is
taken as sufficient evidence to enroll
her in a list of animals. of which the
presumption is that they are good an
imals to breed from to get increased
productiveness. Since the male does
not produce milk, he obviously cannot
be enrolled on such a basis. So he is
put into the advanced registry on the
basis of the performance of his daugh-
ters. If he has a certain number of