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PATTERN OF MORTALITY IN AVIAN NEPHROSIS
RAYMOND T. PARKHURST
United States Department of Agriculture, State
College,
Mississippi
(Received for publication January 24, 1964)
Cosgrove (1962) described a disease of
chickens which has been termed avian
nephrosis because of the tubular degenera-
tive lesions in the kidneys. He observed
that this acute malady, found in many
flocks of young chickens, is characterized
by ruffled feathers, watery diarrhea,
trembling, depression, and severe prostra-
tion. In 2- to 15-week old chickens sudden
signs show in 10 to 20 percent of the flock.
The mortality rate is generally 1 to 15
percent, averaging about 5 percent in 2- to
5-week-old affected birds. He also reported
that mortality is higher in 2-to 4-week-old
birds than in 4- to 5-week-old birds and
generally lasts 5 to 7 days. Lesions in-
cluded severe dehydration, hemorrhages
in the leg and thigh muscles, enlarged
kidneys, ureters filled with urates, and an
enlarged bursa of Fabricus.
In field trials to try to find a product or
management practice which would elimi-
nate or lessen this malady in broilers, a
study was made of mortality records of
1,846,978
broiler chickens started in 180
houses on 28 farms. The farms were prin-
cipally located in the State of Mississippi.
Avian nephrosis had been present on these
farms in one or more broods.
As avian nephrosis is so easily recog-
nized, no attempt was made to get labora-
tory confirmation of outbreaks unless it
was obvious that there was a complication
by the presence of one or more other dis-
eases.
In most cases the grower deter-
mined the day symptoms were first ob-
served and the length of the active period.
The disease was first observed at an
average of 24.7 days and lasted 7.5 days.
The average total mortality was 8.8 per-
cent, of which 5.6 percent occurred during
the period the disease was active.
In these broiler flocks, the earliest that
the clinical manifestations were observed
was 13 days and the latest was 63 days.
The highest mortality was 37.6 percent, of
which 32.7 percent occurred during the
period when the disease was active. The
disease in this instance was first observed
relatively late, at 44 days. Mortality was
back to normal in 6 days.
Graphs showing the weekly percent of
total mortality, in the case avian nephro-
sis is present, normally exhibited a rela-
tively high mortality for about 7 to 8 days
when the chickens were at about 25 days
of age.
Unless there are other diseases present
to complicate the situation, it is usual for
the mortality to return, after the avian
nephrosis period, to about what it was
just before the disease occurred.
Graphs were made of the percent mor-
tality which occurred daily of the total
mortality in the period during which the
avian nephrosis was observed. It was ob-
served that the mortality usually peaked
half-way through the period as illustrated
in Figure 2.
Figure No. 1 shows a graph of a typical
avian nephrosis total mortality record. A
total of 6,600 chicks were started. The
disease appeared at 24 days and lasted 6
days.
The percent total mortality was
10.9.
Figure No. 2 illustrates the daily
distribution of the total mortality within
the avian nephrosis period in the same
brood as in Figure No. 1. The per
cent mortality during the active period
was 6.3.
788
RESEARCH NOTES 789
FIG.
1. A graph of the percent mortality weekly of the total mortality
in a typical avian nephrosis outbreak.
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CONCLUSION
In broiler flocks affected with avian
nephrosis, the first symptoms usually
appeared at about 25 days and persisted
about 7 to 8 days. The graph of the per-
cent mortality that occurred daily of the
total mortality during the period during
which the symptoms were observed is a
characteristic of the disease. It usually
assures its diagnosis. The mortality nor-
mally peaks half-way through the disease
period. As the disease usually persists
FIG.
2. A graph of the percent mortality daily of
the total mortality in the period during which the
avian nephrosis was observed in a typical avian
nephrosis outbreak.
790
RESEARCH
NOTES
from brood to brood, this sudden and
usually relatively high mortality for a
short period of time and its characteristic
curve can often be important. When used
with clinical manifestations and, with or
without the lesions of the disease, it can be
The carob tree {Ceralonia siliqud)
thrives on semiarid regions of Mediterran-
ean countries and is a valuable source of
locust gum which is separated from its
seeds.
The average composition of carob
pods is as follows (Binder et al., 1959):
total sugar as glucose,
43.3%;
crude pro-
tein, 4.6%; crude fat, 0.7%; pectin,
1.43%; fiber, 7.2%; and ash,
1.95%.
Vari-
ous attempts have been made to use seed-
free ground carob pods for feeding chick-
ens.
When levels of 5% to 40% of ground
carobs are used to replace an equivalent
amount of cereals, a marked depression in
the growth of chickens has been observed
(Kratzer and Williams, 1951; Vlachakis,
1959;
Bornstein et al., 1963). The auto-
claving of the carobs overcame this growth
inhibition only to a slight extent in some
reports (Kratzer and Williams, 1951;
Valachakis, 1959) but failed in other cases
(Bornstein et al., 1963). Contrary to the
observations of Vlachakis (1959), Born-
stein et al. (1963) feel that tannin-like
compounds present in carobs may be
responsible for this inhibition in chicken
growth. Digestible nutrients are as low as
57%
in carobs (Bondi and Meyer, 1944).
It is speculated that a part of the
growth depression of chickens by the
feeding of carobs may be due to a de-
ficiency of available energy in the earlier
a valuable tool in the diagnosis of the
disease.
REFERENCE
Cosgrove,
A. S., 1962. An
apparently
new
disease
of
chickens—avian
nephrosis.
Avian
Diseases,
6:
38S-389.
studies. If we consider about 4 kcal./gm.
as the metabolizable energy of sugars and
proteins, the average energy of carobs
would calculate to be about 2 kcal./gm.
The present experiments were designed to
provide approximately equivalent levels
of energy in the control and the test diets,
the compositions of which are listed in
Table 1. These diets were fed to day-old
Arbor-Acre, broiler type chickens housed
in electrically heated battery cages. Each
group contained ten birds which were
weighed two times each week.
The results of these experiments (Table
2) confirm our feeling that diets contain-
ing carobs have a deficiency of energy. If
the diets contained 5% or 10% soybean
oil along with 20% carob, the growth of
chickens was as good as on the control
diets containing ground corn. The addi-
tion of soybean oil tends to improve the
gain in body weight for every gram of
feed consumed. There was very little
difference in the pancreas weights in mg.
per 100 gm. body weight of the chickens of
the various groups.
The amount of locust gum present in
ground carobs must be very small be-
cause the addition of 0.1% Cellulase-100
to the chicken diets, or the use of carobs
which have been reacted with this amount
of enzyme in vitro did not improve the
THE USE OF GROUND CAROBS IN CHICKEN DIETS
PEAN
VOHRA
AND F. H.
KBATZEE
Department
of
Poultry
Husbandry,
University
of
California,
Davis
(Received
for
publication February
10,
1964)
