COOPERATIVE EXTENSION WORK IN
AGRICULTURE AND HOME ECONOMICS
(Acts of May 8 and June 30, 1914)
AGRICULTURAL EXTENSION SERVICE, UNIVERSITY OF FLORIDA
FLORIDA STATE UNIVERSITY, AND UNITED STATES
DEPARTMENT OF AGRICULTURE, COOPERATING
H. G. CLAYTON, DIRECTOR
M. W. EMMEL
Veterinarian, Florida Agricultural Experiment Station
N. R. MEHRHOF
Poultry Husbandman, Florida Agricultural Extension Service
AGRICULTURAL EXTENSION SERVICE
Start with Quality Chicks
Quality chicks mean chicks that come from stock
which is healthy, free of disease; stock which has been
bred for high egg production, egg size, livability, rapid
growth, and fast feathering.
Use Care in Purchasing Chicks
1. Check list of breeders and hatcheries.
2. Buy chicks of well-established and proven strains.
3. Try to find the chicks as near home as possible.
START WITH QUALITY CHICKS ...................... ......................... ................... 2
PULLORUM DISEASE IN CHICKENS ................................................................. 3
Factors Predisposing Chicks to Pullorum Disease ................--.. ............ 7
Occurrence of Pullorum Disease in Chicks from Tested Stock ...-..-..--..... 8
NATIONAL POULTRY IMPROVEMENT PLAN ................................ .................-.... 9
Breeding Stages ....-....--...... --------------.........-..-------- ---------...--..... ....-....-....------- 9
Pullorum-Control and Eradication Classes .................... .... .................... 12
Term s U sed in the N .P.I.P. ................-- ..... ........ ..... ...................... 13
SUBMITTING DISEASED BIRDS TO LABORATORY FOR DIAGNOSIS .-......--......----....... 15
Pullorum Disease in Chickens
M. W. EMMEL and N. R. MEHRHOF 1
Pullorum disease, formerly called bacillary white diarrhea and
BWD, is a common and widespread disease of chickens. Oc-
casionally it occurs among turkeys.
Pullorum disease in young chicks often results in losses as
high as 90 percent of the flock before the birds are three weeks
of age. In many instances most of the survivors do not do
well. In young chicks the disease occurs as a septicemic dis-
ease. That is, the microorganisms which cause the disease in-
vade the blood and in case of death overwhelm the defensive
mechanism of the body. Among adult birds, females or males,
the infection localizes in the reproductive organs, but usually
does not cause excessive mortality unless the disease is ex-
tremely prevalent in the flock.
Probably more is known concerning the nature of pullorum
disease and its control than any other disease of chickens. Yet,
the disease exacts an unnecessarily high toll from the poultry
industry each year. It is the purpose of this publication to
review the practical information on this disease in the hope that
its nature and control will be better understood and unnecessary
Cause.-Pullorum disease is caused by a microorganism of
the paratyphoid group, Salmonella pullorum. This microorgan-
ism can be isolated easily from the tissues of baby chicks affected
with the disease and with considerable regularity from the
reproductive organs of adult birds so affected. This micro-
organism will not live for long periods of time outside the ani-
mal body. Therefore, one of the chief means by which pullorum
disease is transmitted is by infected birds. The microorganism
is killed readily by reliable disinfectants with a phenol co-
efficient of 5 in a 2 percent solution.
Symptoms.-Baby chicks affected with pullorum disease ap-
pear depressed and unthrifty. The wings often droop. Many
chicks emit a characteristic squeaky chirp when droppings are
passed. Diarrhea may or may not be present. In case diarrhea
1The authors are indebted to J. C. Driggers and F. S. Perry of the
Poultry Husbandry Division, Dr. Glenn Van Ness of the Veterinary Division,
and Dr. D. C. Gilles, State Live Stock Sanitary Board, for comments in the
preparation of this bulletin.
develops, the vent may become "pasted". Affected chicks usually
appear sleepy and seek warm spots under the brooder or huddle
in groups. Mortality usually is highest when the disease oc-
curs during the first week of life and may reach 90 percent
by the time the chicks are three weeks of age. At this age
losses subside but some chicks may become "runty" while others
may show retarded growth.
The symptoms described above are not absolutely diagnostic
of pullorum disease. Chicks showing these symptoms should
be suspicioned of having the disease. Many of these symptoms
also may occur as the result of hereditary weakness, poor man-
agement, overheating or chilling. The disease caused by these
latter factors is sometimes called non-specific diarrhea because
it may be caused by any one of a number of factors, rather than
by a specific one only. This type of disease can be differentiated
from pullorum disease both by lesions observed on post-mortem
examination of affected chicks as well as by isolation of the
microorganism, Salmonella pullorum, in the case of pullorum
Adult birds do not show symptoms diagnostic of pullorum
infection. If the disease is extremely prevalent in the flock
some mortality from the infection might occur, but one is un-
able to diagnose the disease from symptoms shown by these birds.
The disease can be recognized by post-mortem examination and
isolation of the microorganism causing the disease from infected
ovaries or testicles.
Lesions.-Irregular grayish or light brown areas appear in
the lungs of baby chicks affected with pullorum disease. These
usually can be observed through the chest wall after the skin
has been removed. The lungs can be inspected closely by cutting
the ribs over this organ with a pair of sharp-pointed scissors.
Very small pin-point hemorrhages or gray spots of similar size
appear on the liver. One to six or seven gray nodules may
develop on the heart in some instances, particularly in chicks
several weeks of age. All of these lesions are diagnostic of
pullorum disease, although all may not occur in each affected
bird. Other lesions, such as pneumonic or congested lungs, un-
absorbed yolk, and accumulations of gelatin-like substance under
the skin and in body cavities frequently occur but may be the
result of disease other than pullorum.
Chicks. which have hereditary weakness or which have been
overheated, chilled or poorly managed often show these latter
lesions but never show those considered diagnostic of pullorum
disease unless this disease actually is present.
The infected yolk sacs of hens affected with pullorum disease
become hard, discolored and misshapen.
Sources of Infection.-Pullorum disease can be transmitted
in a number of ways: (1) from hen to chick through infected
eggs; (2) dissemination of the infection in incubators, particu-
larly forced draft machines when chicks hatch from infected
eggs; (3) brooding chicks in houses or equipment contaminated
with the microorganism which causes the disease; (4) by direct
or indirect contact with infected birds; (5) by male birds.
1. A varying percentage of eggs laid by infected hens carry
the microorganism causing pullorum disease. The chicks from
these eggs are affected with the disease when hatched.
2. During the hatching period the "down" from these infected
chicks distributes the microorganisms causing the disease
to all parts of the incubator. In this manner many healthy
chicks become infected during the hatching period. Thus,
chicks which hatch from infected eggs are a potential source
of infection to every chick hatching at the same time and
unless the incubator is cleaned and disinfected the infection
can be transmitted to chicks of subsequent hatches.
The above two sources of infection are important to hatchery-
men in the control of pullorum disease because the first involves
the parent stock or breeding flock while the second involves
incubation of eggs. The second source of infection is the reason
why hatcherymen should not incubate eggs from non-tested
stock with clean eggs in the same incubator or even in different
incubators in the same room.
3. Pullorum disease can be contracted by brooding chicks
in houses or using equipment contaminated with the micro-
organism causing the disease. This factor can be eliminated
by thoroughly disinfecting houses and equipment between each
brood of chicks.
4. The droppings of baby chicks affected with the disease
contain millions of the microorganisms causing the disease, and
the brooder premises, including drinking water and feed, are
quickly contaminated, making it possible for healthy chicks to
become infected. This microorganism also is spread about the
premises in the droppings of many infected adult birds, making
it possible for healthy birds to become infected. Thus, both
young and adult birds can contract the disease through direct
contact with infected birds. The microorganism causing the
disease also can be carried mechanically from contaminated
premises to healthy chicks in a large number of ways-through
contaminated feed and water utensils, clothing, rodents, improper
disposal of droppings, improper disposal of dead birds, etc.
5. Infected male birds can transmit the infection to hens.
Although a relatively small percentage of pullorum disease is
transmitted in this manner, male birds in a breeding flock must
receive consideration in any control program.
These sources of infection can be recognized as placing a great
burden for the control of pullorum disease on the flock owner
who may be supplying hatching eggs to the hatcheryman, or
who may also be the hatcheryman. The parent stock is recog-
nized as being the chief source of infection listed above. Dis-
semination of the infection in the incubator cannot take place
unless the microorganisms causing the disease are present.
When present, the usual source is infected eggs which, of course,
come from infected parent stock. After being placed in the
brooder a few infected chicks, whether coming from infected
eggs or infection in the incubator, can be a potential source of
danger to the entire brood.
While it is true that the microorganism causing pullorum dis-
ease can be carried mechanically from one premise to another,
the percentage of outbreaks from this source is low. It can be
carried more readily from an infected flock to a non-infected
younger flock on the same farm. The brooder itself can be
eliminated as a source of infection by thorough disinfection
before each group of chicks is placed in it.
As has been mentioned previously, the major losses from
pullorum disease among young chicks occur during the first
three weeks of life. Some chicks recover and it is these birds
in which the infection becomes localized in the reproductive
organs and which serve as a source of infection in the laying
flock. Infection of adult birds also occurs as a result of direct
contact with infected birds. Infected hens pass the micro-
organisms through many of their eggs to the baby chick.
Treatment and Control.-Medicinal agents are of questionable
value in the treatment of pullorum disease and cannot be de-
pended upon as a reliable control measure.
The losses sustained from an outbreak of pullorum disease
in baby chicks will depend in a large measure on the number
of chicks originally infected and the conditions to which they
have been subjected and under which they are being brooded.
The addition of 10 percent of dried buttermilk or 6 percent
of dried whey to the feed often aids in reducing the spread
of the infection; added dried milk should not be fed after the
chicks are three weeks of age and it should not be fed to healthy
flocks of baby chicks. The maintenance of extreme sanitary
conditions is necessary. A disinfectant placed in the drinking
water will reduce the spread of infection to some extent. Dead
chicks should be burned.
The most successful control of pullorum disease consists of
applying the pullorum test to parent stock and subsequently
removing all of the birds which give a positive or suspicious
test. Flock owners as well as hatcheries incubating eggs from
these flocks then must adhere strictly to certain rules and regu-
lations to control the disease. Pullorum disease cannot be con-
trolled in the parent flock unless the owner practices strict
vigilance at all times.
Brooding equipment should be cleaned and disinfected thor-
oughly several days before a new brood of chicks is placed in the
brooder. New broods of chicks should not have contact with
older chicks. Chicks should be purchased from hatcheries in-
cubating eggs from parent stock which has been tested for
pullorum disease. Sanitary conditions should be maintained in
the brooding equipment.
Factors Predisposing Chicks to Pullorum Disease
As mentioned perviously chilling, overheating, hereditary
weakness, poor management and perhaps other conditions can
result in symptoms not unlike those of pullorum disease. How-
ever, these factors often weaken the resistance of chicks, mak-
ing it easier for them to contract pullorum disease. Often the
occurrence of these factors is not the responsibility of the per-
sons rearing the chicks. Chicks occasionally are subjected to
detrimental conditions in transit; this particularly is true when
the shipping distance is long and the weather is changeable.
Thus, it is advisable to purchase chicks as near home as possible.
Regardless of the conditions to which chicks have been sub-
jected, pullorum disease cannot occur unless the microorganism
causing the disease is present. Although infection can occur
from contaminated brooding equipment or be carried to the chicks
in the brooder from an outside source, these sources of infection
are responsible for a minority of outbreaks of pullorum disease.
The hatcheryman as well as the poultry raiser has a very
definite responsibility in the control of pullorum disease. When
informed that a poultryman has lost chicks from an outbreak
of pullorum disease, the hatcheryman often can reply in truth
that 10 or 12 other poultrymen received chicks from the same
hatch and reported no trouble. The group of chicks which de-
veloped pullorum disease happened to be subjected to conditions
which lowered their resistance, thus making them more suscept-
ible. On the other hand, these chicks would not have contracted
the infection had not the microorganism been present.
Occurrence of Pullorum Disease in
Chicks from Tested Stock
Baby chicks should be purchased from breeders and hatcheries
using eggs from parent stock which has been tested for pul-
lorum disease. Officially tested flocks are divided into different
classifications depending upon the percentage of reactors found.
Quite naturally, chicks hatched from eggs from a clean parent
flock are most desirable.
Pullorum disease sometimes occurs in chicks from tested
parent stock. The fact that the hatchery is officially listed as
using eggs only from parent stock which has been tested for
pullorum disease does not necessarily absolve the hatchery from
all blame for an outbreak of pullorum disease among chicks
purchased from them. Neither does it condemn the pullorum-
testing program. Hatcheries must adhere strictly to certain
rules and regulations at all times to reduce the prevalence of
this disease. Any laxity in this respect, knowingly or unknow-
ingly, often leads to outbreaks of pullorum disease. Likewise,
any condition to which baby chicks are subjected in transit or
on the poultry farm which weakens their resistance makes the
chicks more susceptible to pullorum disease.
However, baby chicks cannot contract pullorum disease unless
the microorganism causing the disease is present.
Many poultrymen in Florida purchase chicks from hatcheries
in other states. In some instances, Florida hatcheries purchase
eggs in other states and incubate them in this state. These
chicks and eggs usually originate from parent stock tested for
pullorum disease. However, it should be understood that at
present there is no uniformity of the pullorum eradication pro-
grams as conducted in many states. In some states the Na-
tional Poultry Improvement Plan's minimum requirements are
met; in others the official program adheres to maximum require-
ments. The purchaser of eggs or chicks outside the state should
ascertain the exact status of the parent flock from which they
The pullorum control program is one of the most important
in the poultry industry. Pullorum disease is not easily controlled.
The responsibility of the hatcheryman does not end merely with
the pullorum-testing of the parent stock. He must exercise
vigilance in all of his operations. Likewise, the poultryman
has a responsibility in the control of this disease and his vigil-
ance must be equally as unrelenting.
National Poultry Improvement Plan
The National Poultry Improvement Plan is a voluntary plan
with the state and with individual poultry producers and hatch-
ery operators within the state.
The NPIP became effective July 1, 1935, under the super-
vision of the Bureau of Animal Industry, United States Depart-
ment of Agriculture.
The agency in charge of the plan in Florida is the State Live
Stock Sanitary Board at Tallahassee.
The objectives of the NPIP are to improve the breeding and
production qualities of poultry and to reduce losses from pul-
The plan is divided into two phases, known as the (1) Breed-
ing Stages and (2) Pullorum-Control and Eradication Classes.
Both phases must be carried on at the same time in Florida.
I. U. S. Approved Breeding Stage.-(A). Approved Flocks.-
These flocks shall meet the following requirements: Females
shall be rigidly and thoroughly selected once each year for con-
stitutional vigor and for egg production, such selected females
to combine standardbred and production qualities to a reason-
ably high degree; males shall be selected especially for con-
stitutional vigor and standardbred qualities; the selection of
the flocks shall be approved, by a state inspector.
(B). Approved Hatching Eggs.-Such eggs shall come only
from U. S. Approved flocks or a higher U. S. breeding stage
and shall weigh at least 1 11/12 ounces each.
(C). Approved Chicks.-They shall be hatched only from
U. S. Approved eggs and in U. S. Approved hatcheries.
(D). Approved Hatcheries.-These hatcheries shall be in-
spected and approved by a state inspector at least once during
the hatching season. They may not hatch for sale or sell hatch-
ing eggs and chicks other than those produced under the breed-
ing stages of the plan. Of any one variety, only U. S. Approved
and U. S. R. 0. P. hatching eggs and chicks may be hatched
for sale or sold. Hatching eggs and chicks of the U. S. Certified
stage from other varieties may be hatched for sale or sold by
a U. S. Approved hatchery.
II. U. S. Certified Breeding Stage.-(A). Certified flocks.-
These flocks shall fulfill all the requirements of the U. S. Ap-
proved flocks and shall be mated to U. S. R. 0. P. males. For
the first 2 years of U. S. R. 0. P. work carried on by any breeder
the males for his own flock need not be U. S. R. 0. P. males but
must be individually pedigreed and of breeding which meets the
qualifications for U. S. R. 0. P. males. All such males may be
used in subsequent breeding seasons if reinspected and certified
by the official state agency. The males and females shall be
of at least qualifying standard weight as designated by the
official state agency, in cooperation with the state college of
agriculture or other properly constituted state agency which
gives the prescribed training in selecting poultry breeding stock.
The males and females shall be selected by a state inspector
once each year. This flock inspection shall consist in the exam-
ination of a sufficient number of males and females and the
checking of the wing bands on a sufficient number of males to
satisfy the state inspector that the flock is worthy of certification.
(B). Certified Hatching Eggs.-Such eggs shall come only
from U. S. Certified flocks and shall weigh at least 1 11/12
ounces each and average at least 24 ounces to the dozen.
(C). Certified Chicks.-They shall be hatched only from U. S.
Certified eggs and in U. S. Certified hatcheries, except that a
hatchery may produce and sell U. S. Certified chicks of one breed
or variety and U. S. Approved of another breed or variety, in
which case the hatchery shall be recognized as of the lowest
breeding stage in which chicks are produced.
(D). Certified Hatcheries.-These hatcheries may not hatch
for sale or sell other than U. S. Certified hatching eggs and
chicks, and U. S. R. 0. P. hatching eggs and chicks. They shall
be inspected and approved by a state inspector at least twice
during the hatching season.
III. U. S. Record of Performance Breeding Stage.-(A). R.
0. P. Females.-Pullets shall have laid 200 or more eggs during
the first laying year and yearling and older hens shall have
laid 200 or more eggs during the trap-nest year.
The qualifying average egg weight for pullets shall be 24
ounces to the dozen and for yearling or older hens shall be 25
ounces to the dozen.
All females shall be of at least qualifying body weight for
hens and be reasonably good representatives for each breed or
variety as designated in the American Standard of Perfection.
All birds meeting the requirements with respect to egg pro-
duction, egg weight, eggshell color and texture, egg shape, body
weight, and freedom from standard disqualifications, and that
are reasonably good representatives of the breed or variety
as designated in the American Standard of Perfection, shall
be considered as having met the requirements for U. S. R. 0. P.
(B). R. 0. P. Males.-Males produced from U. S. R. 0. P.
chicks may be qualified as U. S. R. 0. P. males for participants
in the plan only.
(C). R. 0. P. Matings.-These matings shall be comprised of
only U. S. R. 0. P. females mated to U. S. R. 0. P. males.
(D). R. 0. P. Hatching Eggs.-U. S. R. 0. P. hatching eggs
shall come only from U. S. R. 0. P. matings.
(E). R. 0. P. Chicks.-They shall come only from U. S. R.
0. P. eggs.
(F.) The inspector shall inspect the work of each U. S. R. 0. P.
breeder at least five times each year.
IV. U. S. Register of Merit Breeding Stage.-(A). R. 0. M.
Sire.-A U. S. R. 0. M. sire is a male which, when mated to
U. S. R. 0. P. females, has at least one-half and a minimum
of 20 of his daughters that are entered in U. S. R. 0. P. qualify.
(B.) R. 0. M. Dam.-A U. S. R. 0. M. dam is a female which,
when mated to a U. S. R. 0. P. male in an individual pedigree
mating, has at least one-half and a minimum of four of her
daughters that are entered in U. S. R. 0. P. qualify. The females
in U. S. R. 0. P. candidate matings which qualify as U. S. R.
0. P. may qualify as U. S. R. 0. M. through the performance
of their daughters.
Pullorum-Control and Eradication Classes
1. Pullorum-Tested Flocks.-These flocks shall meet the fol-
lowing requirements: (a) All chickens to be used as breeders
shall be tested for pullorum disease when more than five months
of age, under the supervision of an official state agency,, and
shall contain fewer than 4 percent of reactors in 1947-48, and
fewer than 3 percent of reactors in 1948-49, the last test being
made within 12 months immediately preceding the date of sale
of hatching eggs or chicks from such flocks. At the end of the
1948-49 hatching season the U. S. Pullorum-Tested class shall
be deleted from the National Plan; (b) all indicated carriers of
pullorum disease shall be removed from the premises on com-
pletion of the test and disposed of in a manner satisfactory to
the official state agency; (c) all birds remaining in the flock
shall be properly leg-banded; (d) individual birds introduced
into U. S. Pullorum-Tested flocks shall have passed, within 12
months, a negative official test for pullorum disease.
In Florida, the Pullorum-Tested class was deleted in 1946.
2. Pullorum-Controlled Flocks.-These flocks shall meet the
following requirements: (a) All chickens to be used as breeders
shall be tested for pullorum disease when more than 5 months
of age, under the supervision of an official state agency, and shall
contain fewer than 2 percent of reactors, the last test being
made within 12 months immediately preceding the date of sale
of hatching eggs or chicks from such flocks; (b) all indicated
carriers of pullorum disease shall be removed from the premises
on completion of the test and disposed of in a manner satis-
factory to the official state agency; (c) all birds remaining in
the flock shall be properly leg-banded; (d) individual birds
introduced into U. S. Pullorum-Controlled flocks shall have
passed, within 12 months, a negative official test for pullorum
3. Pullorum-Passed Flocks.-These flocks shall meet the fol-
lowing requirements: All chickens to be used as breeders shall
be tested for pullorum disease when more than 5 months of age
under the supervision of an official state agency, shall be of-
ficially leg-banded, and shall contain no reactors, the last test
being made within the testing year immediately preceding the
date of sale of hatching eggs or chicks from such flocks.
4. Pullorum-Clean Flocks.-These flocks shall meet the fol-
lowing requirements: (a) All chickens to be used as breeders
shall be tested for pullorum disease when more than 5 months
of age, under the supervision of an official state agency, shall be
officially leg-banded, and shall contain no reactors in 2 consecu-
tive tests not less than 6 months apart, or in 3 consecutive tests
not less than 30 days apart, the last test being made within the
testing year immediately preceding the date of sale of hatching
eggs or chicks from such flocks; (b) once a flock is established as
U. S. Pullorum-Clean it remains so as long as no reactors are
found in the official annual test of birds used as breeders; (c) a
flock developed exclusively from purchased hatching eggs pro-
duced by a U. S. Pullorum-Clean flock and hatched in a U. S.
Pullorum-Clean hatchery may be recognized as a U. S. Pullorum-
Clean flock in one annual test conducted under the supervision
of an official state agency if no reactors are found.
Terms Used in the NPIP
All poultrymen should know the meaning of terms used in
the breeding stages of the program.
Approved means that breeding flocks, hatching eggs and
hatcheries have met minimum requirements to enter program.
Certified indicates that breeding flocks, hatching eggs, chicks
and hatcheries have met more rigid requirements than above.
Record of Performance means that the breeding flocks have
met still more rigid requirements, particularly insofar as egg
size and production are concerned.
Register of Merit signifies a superior breeding program, the
The following terms are used in connection with pullorum-
control and eradication:
Pullorum-Tested.-Flock tested within last 12 months and
less than 4 percent reactors found.
Pullorum-Controlled.-Same as above but less than 2 percent
Pullorum-Passed.-Flock tested within last 12 months and no
reactors found (one clean test).
Pullorum-Clean.-Flock which has passed 2 consecutive clean
tests not less than 6 months apart.
In Florida, the "breeding stages" and "pullorum-control and
eradication classes" must be carried on at the same time. A
Florida breeder or hatchery cannot participate in only one phase.
The Florida State Live Stock Sanitary Board is the official
state agency in charge of the National Poultry Improvement
Plan. Write to this agency at Tallahassee for information re-
garding participation in the NPIP program.
Submitting Diseased Birds to
Laboratory For Diagnosis
In sending diseased birds to the Poultry Disease
Laboratory, Florida Agricultural Experiment Station,
Gainesville, for diagnosis, one should attempt to select
birds which show the typical symptoms of the disease
affecting the flock. It is well to select several just com-
ing down with the disease and several well-advanced
Chickens, adult or young, which die on the farm are
not very good specimens to submit. They invariably
arrive "too decomposed for examination," particularly
during the summer.
Sick birds can be shipped by express. It is against
Postal Regulations to mail sick chickens by parcel post.
Birds should be sent so as not to arrive on Saturday or
Specimens-tumors, organs, or parts of birds-can
be submitted by placing in a screw top jar and filling
it with clean salty water (4 heaping tablespoonfuls of
table salt per cup of water). The jar should be wrap-
ped carefully to insure against breakage in the mails.
A letter describing the outbreak of disease, viz., his-
tory of outbreak, age of birds, extent of losses, duration
of illness, etc., is always very helpful in arriving at a