Oxford Democrat., 1919-12-09
Breeding Poultry for High Layers.
THE LAWS OF INHERITANCE FOUND By
LONG EXPERIMENT..

THE LAWS OF INHERITANCE FOUND BY
LONG EXPERIMENT.
Back in 1898 when the saying wac
prevalent that there was mo scrub like
q Thoroughbred scrub", the Maine Agri
cultural Experiment Station undertook
breeding experiment to determine the
laws of Inheritance Of egg production.
By knowledge of these laws once de.
sermined the biologists of the Station
connected with the work meant to pu'
the scrub where 1t belonged, and make II
80 that In fact there should be no suci
thing as a "thoroughbred' scrub in
poultry.
The success of this experiment is to
day common knowledge to many who
will read this. There are, however, few
who realize the amount of labor ex
pended to discover those simple facts.
The object of the investigation stated
concretely is contained in the opening
sentence Of the first report on this sub.
| iect, "For several years the Station has
been breeding with the hope OF establish.
ing families or strains of hens that shall
excel as egg producers. 1t is known thai
the laws Of inheritance and TRANSMISSION
are az true with birds as with other ami.
mails and when We consider the wonder.
ful advance in egg production that tht
ben has made since domestication, there
is ample reason for assuming that
higher average production than the pres
ent can be secured. It was found In
i kaf hn mr. rafnl aalan
| tiop (the selection on the basis of shank
color and conformation were then known
to our biologis) We we're including IL
our breeding pens birds that were moi
great producers" To remedy this diff
Guilty the trap nest was invented. The
first of its kind, it has since been copieo
in principle by many manufacturers and
poultry men.
At this time work of this kind wa.
unheard of, it was subject to ridicule and
embarrassment of many kinds. 1t wat
the pioneer of the highest order and like
| the pioneer "tbe handwriting appeared
on the wall" sometimes before 1t was
recognized.
In 1911, thirteen years after the study
was begun, the problem was solved. The
facts determined may be boiled down to
the following terse conclusions:
n) The record of egg production of
hen, taken by itself alone, gives no defi
| mite, reliable indication from which tn.
probable egg production of her daugh
ters may be predicted. Furthermore,
mass selection on the basis OF egg laying
records of females alone, even though
long continued and stringent in charac-
ter, completely failed to produce any
steady change in type in the direction oi
selection.
(2) Differences in egg producing abil
| ity are, In spite of the above results, Ger.
tainly inherited.
(3) The number of visible oocytes (po'
tential eggs) on the ovary bears no deii
nite or constant relation to the actually
realized egg production.
N This can only mean that observed
differences (vsriations) in actual egg pro
duction depend upon differences in the
complex physiological mechanism con-
cerned with the development OF oocytes,
and the separation of them from the
ovary and the body (layine).
(5) 1t is found to be the case that
birds fall into three rather well-defned
classes in respect to winter egg produc-
ton. These include (a) birds with high
winter records, (b) birds with low winter
records, and (c) birds which do not lay
at all In the winter period. The division
point between a and b for the Barred
Plymouth Rock used in these expert.
m epts falls at q production of about 30
eggs.
i6) High productiveness may be in
herited by daughters from their sire, In
dependent of the dam.
jD High laying ability is not directly
inherited by daughters from their dam.
(S) Mediocre or poor laying ability
may be inherited by the daughters from
either sire or dam, or both.
10y Constitutional vigor and hatchinR
ability are Inherited in the same manner
as the character egg production.
From these results mode OF proceed
ure can be devised to increase the egg
production of the poultrymap's flock.
The first and perhaps as important as
any point is to select only birds for
breeding which have constitutional vigor.
Let the scales determine the growth; the
deaths In shell, chick mortality and any
sick ness be charged against the parents
in determining their vitality.
The use of breeders of such females
only az have shown themselves by trap
nest records to be high producers, since
it is only from such females that there
/ can be any hope of getting males capable
of transmitting high laying qualities.
The use as breeders of such males only
az are known to be the sons of high pro.
ducink dams, since only from such males
can we expect to get high producing
daughters.
Keep some adequate pedigree system
W thereby 1t is possible to tell what indi'
yidual male bird was the sire OF any par,
ticular female.
The making when the flock Is started
of as many different matings as possible
This means the use Of az many different
male birds as possible, which will fur.
ther imply small matipgs with only com
paratively few females to single male
Continued, though not too narrow, In
breeding Tor line breeding) of those lines
in which the trap nest records show
preponderant number of daughters OF
given cock bird to be high producers
One should not discard ell but the single
best line, but should keep half dozer
at least OF the lines which throw the
highest proportion of high layers, breed
ing each line within itself.
That the fundamental aspects OF egg
production should have turned out to bt
so extraordinarily simple supports tht
Maine Station in the belief that the In
heritance of equally or possibly more
important quantitative characters may
be entirely spproachable. Thus trusting
in our investigation, the results of which
are Just Cited, we undertook In 1914 a
the request of the Maine State Dairy
men an experiment to determine the In
heritance and physiology OF milk pro
duction, butter-fat percentage and but
ter.fat. As the previous results hav'
; shown Il is In the second generation
that the most important results are ob
. tanned! This takes not less than si1
years for the whole herd. The con
sum ption OF time has been even NOR
than this. All tho first generation mat
> ipgs could not be made at once due I,
lack of sufficient original animals. l
> took In actual time years to approx
mately complete this first generation. l
will take not less tban8 years to get
, calf from each of these first generation
animals and We will need the milk rec
b ords of several OF these second genera
4 L-tS... 80 oor, rlokolv o0aluZa th