THE LAYING HOUSE PERFORMANCE ,
OF CHICKENS BROODED; AND REARED‘
ON FLOORS AND IN CAGES

Thesis for the Degree of Ph. D.
MICHIGAN STATE UNIVERSITY
HOWARD Em WILDEY
1969

 

 

ESIS

LIBRARY

Michigan Stave
University

 

This is to certifg that the
thesis entitled

The Laying House Performance of Chickens

Brooded and Reared on Floors and in Cages

presented by

Howard Edwin Wi ldey

has been accepted towards fulfillment
of the requirements for

Doctor of Philosophy degree in Poultry Science

4%; 74inch,

Major professor

Date Jme 26, 1969

0-169

 

 

 

 

 

 

 

ABSTRACT

THE LAYING HOUSE PERFORMANCE OF CHICKENS BROODED
AND REARED ON FLOORS AND IN CAGES

BY

Howard Edwin Wildey

There is a lack of information on the relationship
of management and nutritional aspects of caged pullet
rearing to economic egg production. It was therefore of
interest to evaluate the subsequent performance of pullets
reared under four methods: in cages without a coccidio-
stat in the diet, in cages for the same period with a
coccidiostat in the diet, on litter to seven weeks of age
and then in cages to 20 weeks of age, and on litter to 20
weeks of age. Five levels of phOSphorus were factorially
combined with the four rearing methods (20 factorial com—
binations). Pullets grown in these combinations were
compared for mean body weight at 20 weeks of age and for
production in single bird density laying cages.

Day-old commercial White Leghorn type pullets were
used in this experiment. No debeaking was done. The
pullets reared on the floor were significantly lighter in
body weight and consumed significantly less feed than

pullets reared in cages or in the floor—cage rearing methods.

 

 

 

Howard Edwin Wildey

Mortality percentages by rearing method were 1.33 (cages-
no coccidiostat), 2.00 (cages-coccidiostat), 5.33 (floor—
cage combination) and 6.66 (floor). There were significant
differences among the rearing methods in mortality. No
significant differences in body weight at 20 weeks of age
due to diet treatments were found.

The same diet was fed to the birds in all treat-
ment combinations during the production phase. No signif—
icant differences in performance were found among the
treatment combinations during the production phase
regarding egg production, egg weight, Haugh Unit or shell
thickness values.

Experiment 2 was conducted to test the effect of
rearing density, i.e., 10, 20, 30 or 40 chicks (density
levels 1 through 4, respectively) per 24 inches wide x
22 inches deep x 16 inches high cage, on performance
during the subsequent production phase.

A total of 330 White Leghorn type day-old pullets
were separated into three weight class intervals that
differed in weight by three grams. Equal numbers of
chicks from each weight class were wing-banded for each
rearing density to be tested. Feeder space per chick
for rearing densities 1 through 4 was 2.5, 1.2, 0.8 and
0.6, respectively. At seven weeks of age, one-half of

the pullets were transferred to identical cages, thus

 

Howard Edwin Wildey

doubling feeder and cage floor Space for the remainder
of the period to 20 weeks of age.

Fifty-four pullets from each rearing density level
were selected equally from the three weight classes.
Eighteen pullets were housed at one bird per cage in 8
inch x 16 inch cages and the remaining 36 were placed in
the same size cages at two birds per cage. All pullets
received the same laying diet. Records of production
were obtained from 22 weeks of age through six 28-day
production periods.

At 20 weeks of age the pullets reared at density
4 were significantly lighter than those reared at the
other densities and had consumed significantly less feed.
The pullets reared at density 1 consumed significantly
more feed than did the pullets in the other treatment
levels.

No significant differences were found among the
means of number of eggs laid by pullets surviving the
six 28-day production periods at either one or two birds
per cage laying density. However, there were significant
differences in hen-day production where the pullets were
housed at two birds per cage; whereas no significant
differences were found where they were housed individually.
The pullets reared at density levels 3 and 4 had signif-

icantly lower hen-day production than those reared at

 

Howard Edwin Wildey

levels 1 and 2. In the first production period, the
pullets reared at density levels 3 and 4 and subsequently
housed at one bird per cage laid significantly larger
eggs than those that had been reared at density levels 1
and 2; however no significant differences were found for
this trait when data from the first three production
periods were analyzed. No significant differences were
found for this factor when the pullets were housed at

two birds per cage.

 

THE LAYING HOUSE PERFORMANCE OF CHICKENS BROODED

AND REARED ON FLOORS AND IN CAGES

By

Howard E. Wildey

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY
Department of Poultry Science

1969

 

ACKNOWLEDGMENTS

The author wishes to express his appreciation to
Dr. Theo H. Coleman, Professor of Poultry Science, for
his guidance and interest in this study and his direction
and helpful suggestions in the preparation of this manu-
script.

The author is sincerely grateful to Dr. Cal J.
Flegal, Assistant Professor of Poultry Science, for his
guidance and direction in the development of the research
regarding this study.

Acknowledgment is also due Dr. Howard C. Zindel,
Head of the Poultry Science Department, for his COOpera-
tion and provision of facilities to carry out this study.

Finally, the author is warmly appreciative of the
assistance and encouragement shown by his family: wife,
Mary Evelyn; daughter, Mary Marguerite; and son, Edwin,

during this important period of study and research.

ii

 

TABLE

LIST OF TABLES . . . . . .
INTRODUCTION . . . . . . .
REVIEW OF LITERATURE . . .
OBJECTIVES . . . . . . . .

Experiment 1
Experiment 2 . . . . .

HYPOTHESES . . . . . . . .

Experiment 1 . . . . .
Experiment 2

MATERIALS AND METHODS . .
Experiment 1 . . . . .

Procedure . . . .
Results . . . . .

Experiment 2 . . . . .

Procedure . . . .
Results . . . . .

DISCUSSION . . . . . . . .
SUMMARY . . . . . . . . .

LITERATURE CITED . . . . .

OF CONTENTS

iii

Page

iv

21

21
22

24

24
24

25
25

25
33

46

46
49

64
74

78

 

Table

10.

ll.

12.

LIST OF TABLES

Starting and growing diets fed to replace—
ment pullets from day—01d to 7 weeks of age,
Experiment 1 . . . . . . . . . . . . . . . .

Growing diets fed to replacement pullets
from 7 to 14 weeks of age, Experiment 1 . .

Growing diets fed to replacement pullets
from 14 to 20 weeks of age, Experiment 1 . .

Analysis of variance of 7-week pu11et
weight, Experiment 1 . . . . . . . . . . . .

Seven-week pullet weight by rearing
method, Experiment 1 . . . . . . . . . . . .

Seven-week pu11et weights by diets,
Experiment 1 . . . . . . . . . . . . . . . .

Seven-week pullet weights by weight classes,
Experiment 1 . . . . . . . . . . . . . . . .

Analysis of variance of 20—week pu11et
weights, Experiment 1 . . . . . . . . . . .

Twenty-week pullet weights, feed consumption
and mortality, Experiment 1 . . . . . . . .

Twenty—week pullet weights, feed consumption
and mortality by diet, Experiment 1 . . . .

Twenty—week pullet weights by weight
class, Experiment 1 . . . . . . . . . . . .

Days of age at 50 percent production,

168 day egg production, mortality and

feed efficiency by rearing methods,
Experiment 1 . . . . . . . . . . . . . . . .

iv

Page

27

28

29

34

34

35

36

37

38

4O

41

43

Table Page

13. Days of age at 50 percent production,
168 day egg production, mortality and
feed efficiency by diets, Experiment 1 . . . . . 44

14. Analysis of variance of seven week body
weights, Experiment 2 . . . . . . . . . . . . . 50

15. Analysis of variance of 20—week body
weights, Experiment 2 . . . . . . . . . . . . . 50

16. Comparison of mean body weights, feed
used and mortality for pullets by initial
rearing density at seven weeks of age,
Experiment 2 . . . . . . . . . . . . . . . . . . 51

17. Comparison of mean body weights, feed
used and mortality for pullets by rearing
density at 20 weeks of age, Experiment 2 . . . . 52

18. Effect of population density during rear-
ing (0 to 20 weeks of age) on subsequent
performance when housed in single bird
cages, Experiment 2 . . . . . . . . . . . . . . 54

19. .Effect of population density during rear-
ing (0 to 20 weeks of age) on subsequent
performance when housed at two birds per
cage density, Experiment 2 . . . . . . . . . . . 56

20. Comparison of percent hen—day production
of pullets housed in single bird cages by
weight class, Experiment 2 . . . . . . . . . . . 58

21. Comparison of percent hen-day production
of pullets housed at a density of two birds
per cage by weight class, Experiment 2 . . . . . 58

22. Effect of population density during rear—
ing (0 to 20 weeks of age) on subsequent
egg weight and production quality criteria,
of pullets housed at one bird per cage,
EXperiment 2 . . . . . . . . . . . . . . . . . . 59

23. .Effect of population density during rear-
ing (0 to 20 weeks of age) on subsequent
egg weight and production quality criteria,
of pullets housed at two birds per cage,
Experiment 2 . . . . . . . . . . . . . . . . . . 59

Table

24.

25.

Page

Effect of pOpulation density during rear—

ing (0 to 20 weeks of age) on subsequent

egg weight and production quality criteria

(average of trait data for first three

production periods) for all pullets housed . . . 61

.Production feed efficiency (kilograms of

feed per dozen eggs) by rearing density

and housing cage density, Experiment 2 . . . . . 62

vi

INTRODUCTION

The rapid development of fewer but larger and
more Specialized egg production units has emphasized the
need for efficiency in pullet production. Egg producers
have found themselves in a highly competitive business
where efficiency is one of the keys to survival. Conse-
quently, they are receptive to innovations that lead to
a reduction in costs of production. An innovation is an
idea perceived as new by the individual (Rogers, 1962).

An important economic factor in the production of market
eggs is the replacement pullet, her production cost, and
her performance regarding egg numbers, egg size and
interior egg quality, shell quality and livability.

The use of wire floors and wire floor cages for
growing replacement pullets is not new. Poultry researchers
have used battery brooders for years and, although batteries
are not used extensively in commercial poultry operations
because of poor labor efficiency, some growers still use
them to start chicks and poults for a brief period. In
intensive production areas of California where extensive
change in management technology tends to be more readily

accepted than in other production regions, the practice

of rearing chickens on wire has been in use for several
decades (Bell, 1967).

The use of caged rearing procedures for producing
pullets appears to be a natural procedure as commercial
poultrymen move toward environmental control and increased
house density. Rearing and housing methods have been
areas of important concern in the poultry industry for
many years and are considered vitally related to the cost
of producing market eggs. However, range and confinement
methods of rearing pullets have been used extensively in
most production areas until the last few years. Recently,
the development of cage brooding and/or rearing systems
has received a great deal of attention. Some experimental
work comparing range with confinement pullets, and range
and confinement pullets with colony cage reared birds has
been reported in the literature. However, except for
field trials, reports in the literature show little work
comparing the egg production of birds grown in cages from
day old to 20 weeks with that of birds grown in combina-
tion floor and cage rearing systems and/or with that of
birds grown on the floor by conventional confinement
rearing procedures.

It has been generally appraised that cage rearing
is more expensive than conventional systems of floor

rearing, yet Bell (1967) reported that both floor and

wire rearing is practiced in Riverside County, California,
where six and one-half million layers on 225 farms were
kept in cages. His 1965 survey showed that 67 percent

of the commercial poultrymen in that locality maintained
their birds on wire through rearing and production. In
this survey, 12 percent of the poultrymen brooded the
birds on the floor and moved them to wire cages when they
were eight weeks of age and 13 percent of these producers
reared their birds on the floor to 18-20 weeks of age.
Bell (1967) reported further that in some instances where
poultrymen had built new floor rearing facilities in the
hope of raising a better pullet, they were forced to
convert to cage and wire rearing to overcome severe
disease problems. His observations suggest that disease
problems associated with intensification may be better
controlled when replacement pullets are grown on wire or
in cages. Since healthy, productive replacement pullets
are essential for financial success in commercial egg
production, many producers feel that cage rearing is worth
the extra $0.50 (Bell, 1967) or $0.73 (Brown, 1969) per
bird initial investment cost required for cage rearing.

If we assume that the extra cost of cage rearing facilities
is $0.50 per bird above that of conventional floor rearing,
and that this cost is spread over 50 birds, the extra cost

of the cage system is one cent per replacement pullet.

This may be a minor additional expense if uncertainty is
generally eliminated from the replacement pullet growing
enterprise and risk is reduced to a manageable proportion of
. pullet production cost.

Claybaugh (1966) reported that growing pullets on
wire is not without problems. He observed that management,
rations, and feeding must be developed to produce the best
pullet possible under this regime. He stated further that
the action of progressive producers in important production
areas indicate a definite trend toward cage rearing. The
advantages and disadvantages claimed for this system of
pullet rearing seem to be based on little more than field
observations. (Flegal et a1. (1966) have listed these pos-
sible advantages and disadvantages as follows:

Advantages
1. Elimination of losses due to crowding and smothering.
2. Elimination of coccidiosis and intestinal parasites.
3. Birds are accustomed to cages when moved to laying
cages.
4. Dust is reduced and this helps reduce respiratory
problems.
5. The cage system affords better working conditions.
6. .Feed consumption is reduced when properly controlled.
7. There is increased efficiency in the use of labor,

capital and housing.

5
8. Fuel costs are reduced.
9. Flocks are more uniform in size and appearance.
10. The cost of litter is eliminated.
11. There is better control of management factors.
12. The overall cost of producing pullets is reduced.
Disadvantages
1. Birds reared in cages should not be sold for floor
layer operations because they lack immunity to
coccidia.
2. Pullets often have a poorer appearance to prospec-
tive customers.
3. A higher total investment in production facilities
is required.
4. Management systems must be changed.
5. Temperature and ventilation are more critical.
6. Cannibalism can be a serious problem.
7. During certain periods, the labor requirements are
extremely high.

Description of Brooding and Rearing
Systems in General Use

 

 

1. Floor brooding is generally a one-step process
in which the chick is started in a brooder house and kept
there until she is 16 to 22 weeks of age, and then moved
into laying quarters; cages or a litter operation.

2. Litter floor brooding to wire or cage combina-

tions: In this system, the chicks are usually grown from

day-old to six to 10 weeks of age in a conventional floor
house and then are moved to either wire or cages to be
grown until maturity. While on the floor, 2/3 to 3/4 of
a square foot of floor space per bird is allowed.

3. In some instances chicks are started on wire
floors at day-old and grown to maturity under the same
conditions. The floor space allowed with this system may
be less than the one square foot per bird that is generally
allowed for a floor Operation. Hovers are generally used
as the heat source.

4. A wire floor to cage system may be used. In
this system, the chicks are started on wire at day—old and
grown to six to 10 weeks of age with about 1/2 square foot
of floor space per bird. At six to 10 weeks of age the
birds are moved into rearing cages.

5. Two cage rearing systems are being used
currently. In one type the birds are raised in cages in
the same house from day-old to 20 weeks of age. This is
done in either of two ways: (1) two sets of cages are
used, one for starting and one for growing, or (2) one
set of cages is used to start the birds and they are
continued in the same cages to 20 weeks of age. This
latter system of cage rearing has the advantage over other
wire systems in that birds are not moved to another house

during the brooding and growing period. Further, it

results in saving the labor costs of moving and also it
eliminates the stress on the birds due to moving and a
change in environment. The birds are fed by the use of
an auger cart or mechanical feeder and water is provided
by a continuous flow or cup water system. A disadvantage
is that the heating system is used for only six weeks out
of the 20 week growing period.

In the second cage rearing system, chicks are
grown from day-old to six to eight weeks of age in
starter cages at which time they are moved to grower
cages where they remain until they are 20 weeks of age.
As with the first system, mechanical feeders and auto-
matic water systems are generally used. This system
allows for a more continuous use of the starting cages
and the associated heating system. Under this system,
three cage rearing houses are required if the starting

cage house is to be used to capacity.

REVIEW OF LITERATURE

Good pullets are considered to be absolutely
essential for the economic success of an egg production
unit. This fact has led to considerable research to test
the effect of rearing methods and procedures on subsequent
production.‘ Stevenson and Bryant (1944), Heuser et_al.
(1945), Johnson and Davidson (1957), Taylor gt_al. (1957),
Bailey gt_al. (1959b), Pepper et;al, (1959), and Winter
(1957) found no significant differences between the laying
house performance of pullets reared on range and those
grown in floor pens in confinement. Kinder and Yoes
(1956), Winter and Schlamb (1948) and Tomhave (1960) found
that range reared pullets laid at a higher rate than those
reared in confined floor pens. Tomhave (1960) found that
New Hampshire pullets grown on range not only laid more
eggs, but that the eggs were larger and hatched more
chicks that had better livability than was the case for
confinement floor reared birds of the same breed.

Pearl and Surface (1914) have shown that either
weight or bulk may be used as a measure of size in fresh
eggs. Jull (1952) presented the factors in pullet

rearing and layer management that affect egg size and

quality. He stated that certain environmental and
physiological factors affect egg weights. Pullets fed
diets relatively low in protein and that are hatched
during the winter tend to lay smaller eggs than those fed
higher protein diets and are hatched during the spring
and the month of September. High summer temperatures
tend to reduce both egg size and shell quality.

Early sexual maturity, according to Jull (1952),
is important in securing high first year egg production
records. However, the lack of persistency makes for the
greatest difference in total egg record. Late sexual
maturity makes for the least difference in total egg
record (Hays, 1944). Researchers have observed that egg
weight is determined by the size of the yolk and oviduct
(Asmundson, 1931) and it has been demonstrated that the
weights of the other egg components are greater as the
size of the oviduct increases (Asmundson and Jervis,
1933).

Earliness of sexual maturity is economically
desirable when associated with reasonably good egg size.
It is obvious that the earlier in life a pullet commences
laying, the sooner it produces some income for its owner.
The work of Hays (1933), Funk (1935) and Callenbach (1934)
confirmed a positive relationship between egg weight and

body weight of the pullet at the start of egg production.

lO

Ideally, a pullet should be reared so that sexual
maturity is delayed until it has adequate body size to
lay an acceptable percentage of medium or larger size
eggs (23 ounces per dozen or more). Wolford (1964)
summarized the recent research on the subject of delayed
sexual maturity in replacement pullets. He stated that
either the use of controlled light period or restricted
feed programs is effective in delaying sexual maturity
of replacement pullets, but controlled lighting seems to
have a greater degree of influence on rate of maturity
than does restricted feeding. Restricted lighting pro-
grams differ according to housing conditions used. Two
light control programs are available to delay the sexual
maturity of replacement pullets: (l) a restricted light
program to be used in conjunction with windowless houses;
and (2) a decreasing light program to be used in houses
with windows. The program for windowless houses consists
of rearing birds under 12 hours of light until they are

8 to 10 weeks of age. The birds are then given 6 to 9
hours of light until they are 20 to 22 weeks Of age. It
is used throughout the year. In the program for houses
with windows a decrease in length of the daily light
period is applied at periodic intervals through the
rearing phase. The producer using this system first deter-

mines the total number of natural daylight hours (sunup

11

to sundown) at the time that the birds will be 22 weeks
of age. Then to this figure 7 hours are added. The
resulting sum is the amount of light required during the
first week of the rearing period.~ After the first week,
the daily light period is decreased 20 minutes per week
until the birds are 22 weeks of age. The programs
recommended by various breeding firms may vary somewhat
from these recommendations but the principles involved
remain the same.

The advantage of restricted light over natural
daylight for growing pullets is that sexual maturity can
be delayed one to three weeks with the controlled system.
The disadvantage of a restricted light program is that it
requires a completely darkened building. This practically
makes an environmentally controlled house a necessity with
the additional cost of insulation and ventilation. This
is not too serious since economic production of pullets
in most regions requires this type of housing. A time
clock controls the length of light period automatically.

A restricted feeding program requires a great
deal of work and effort on the part of the pullet grower,
according to Wolford (1964). Ringrose (1958) has prepared
a feeding guide which showed the pounds of feed that
should be allowed for 100 birds at various ages in weeks

throughout the pullet growing period. High fiber feeding

12

programs are also used to restrict nutrient intake
(Wolford, 1964 and Taylor §E_al., 1957).

The size of pullets grown under any rearing
regime is important because pullet body size at the
beginning of lay may affect egg size. Until recently,
the general procedure was to rear replacement pullets in
floor pens in confinement at a density of one square
foot of floor space per bird from day-old to 20 weeks of
age.

Hartung (1955), Brooks §E_al. (1957), Heishman
g£_al. (1952) and Moreng §E_al. (1961) found that increas—
ing pOpulation density beyond a certain point reduced the
average size of chicken broilers. However, Siegel and
Coles (1958) observed little if any effect on the body
weight, feed efficiency or livability of broilers grown
at densities ranging from one-half to one and one-half
square feet of floor space per bird.

Magruder and Nelson (1961) reared White Leghorn
pullets under two feeding regimes, restricted and full-
fed, and supplied six hours of light daily from three to
21 weeks of age. When subsequently housed in an all slat
floor, mechanized, high density laying house, there was
little difference between the two groups as to total
production. However, the pullets fed a restricted diet
laid a significantly higher percentage of large eggs which

also tended to have a higher albumen quality.

l3

Ernst and Coleman (1966) used Coturnix quail tO
determine the feasibility Of using quail as a substitute
for chickens and turkeys in environmental studies. These
researchers found that when quail were reared at densities
Of 4 or 17 birds per square foot from hatching to onset Of
egg production, and were then placed in individual cages
for 100 days, the egg production was not significantly
different.

The trend in poultry management has been toward
denser pOpulations in growing and production poultry.
Kimber (1941), Hoffman and Tomhave (1945), Nordskog (1959),
Siegel (1959) and Fox and Clayton (1960) found that, in
laying hens, egg production per bird decreased as floor
space per bird was decreased. Champion gt_al. (1962)
found no difference in egg production between birds
housed in floor pens at 1.25 or 2 square feet per bird
during the laying period.

Wolford and Coleman (1960) found that when
Beltsville Small White or Broad Breasted Bronze turkeys
were kept at high population densities, egg production
per unit Of floor space increased but fertility in
naturally-mated turkeys decreased.

Though the majority Of new commercial layer
Operations have birds housed in laying cages, this is a

rather recent development and research on laying cages

14

versus floor type Operations has produced varied results.
Parker and Rodgers (1954) found no consistent differences
in egg production or mortality in tests which compared
the performance of layers in floor pens, individual cages
and colony cages. Gowe (1955) Obtained better production
from floor housed birds but had lower mortality in cage
housed birds. Hill §E_al. (1957), Miller and Quisenberry
(1959) and Bailey gE_al. (1959a) Obtained higher egg
production from cage housed birds. Bailey gt_al. (1959a)
found that cage housed birds laid heavier eggs and had
heavier body weights. Miller and Quisenberry (1959)
Observed lower mortality in the cage housed birds than in
those housed in floor pens.

Champion and Zindel (1968) evaluated the perform-
ance Of pullets housed in (l) individually in 8 inch
cages, (2) two birds to a cage in 8 inch cages, (3) three
birds to a cage in 12 inch cages, (4) four birds to a
cage in 16 inch cages, and (5) six birds to a cage in 24
inch cages. All cages were 16 inches deep. They found
no great differences in average random sample body weights
at 500 days Of age or in 400th day average egg weight.
They concluded, from their data, that income per unit Of
cage space can be maximized by using multiple cage units
in preference to caging layers individually. The poultry-

man's ability to control cannibalism was suggested as

 

15

being the determining factor as to whether individual
or multiple cages are used.

Only limited research data are available dealing
with the rearing Of replacement pullets on wire or in
cages. A number of articles based upon survey data have
been published in the poultry press. Shupe and
Quisenberry (1961) reported the first research data that
involved subsequent production tests Of cage-reared birds.
However, their work involved rearing in cages only during
the latter part of the growing period. In their trial,
pullets were reared on the floor for 14 weeks in conven-
tional, confinement pens. At 14 weeks, the pullets were
equally divided among floor pens, range and colony cages,
either 25 or 35 pullets per 3 1/2 x 8 foot colony cage.
Equal numbers Of cages had slat and wire floors. During
the subsequent rearing period, significant differences in
body weight were Observed. The colony cage reared birds
were heaviest in body weight and consumed the most feed.
The range reared birds were significantly heavier in body
weight than those reared in floor pens. Rearing mortality
was highest for birds in the colony cages and lowest for
those in the floor pens. Pullets from each rearing
environment were subsequently housed in colony laying cages.
During the production period no significant differences in

average body weight, egg production, egg weight, feed

l6

 

efficiency or mortality attributable to the different
rearing treatments were found.

Magruder and Nelson (1968) compared three rearing
regimes: (1) floor confinement, (2) floor confinement
and cage combination, and (3) cage rearing from day-Old
to 20 weeks Of age. Comparisons were made for body weight,
feed consumed, feed conversion and mortality as well as
for subsequent production. They found that the three
rearing systems produced pullets Of about the same body
weight at 20 weeks. Rearing mortality was lowest for the
floor rearing system (0.83 percent). The cage reared
birds consumed the most feed (1.98 kgs.) but the floor-
cage combination and cage rearing systems had the highest
mortality (3.72 percent each).

Bell (1969) reported the results Of four field
trials to measure the effect Of crowding pullets in 24 x
24 inch cages in commercial controlled environment brooder
and growing houses. In the first trial, chicks were
placed in cages at the rate Of 6, 8, 10, 12, l4, l6, l8
and 20 per cage at one day Of age. Dead birds were
replaced throughout the trial with equal numbers Of banded
pullets Of the same age. Each cage had 24 inches Of
mechanical feeder space. The pullets were weighed at 6,
10, 12 and 16 weeks Of age. Debeaking was done at 13 1/2

weeks Of age. It was found that the average body weight

17

at each age tended to gO down as density was increased.
At 10 weeks Of age, the birds in the 8-bird cage were
closest to the breeder's goal for body weight. At 12
weeks Of age, birds in both the 8 and lO—bird cages were
closest to the breeder's goal of 2.3 pounds or 1.044 kgs.
average body weight. Though greater densities resulted
in lower weights, this researcher Observed that some
grower managers might require fewer pullets per cage to
reach the Optimum weight while others might achieve this
weight with somewhat higher density. NO significant
differences were found in variability Of body weights or
in mortality among the density levels.

A second trial in the same house was conducted
using densities Of 8, 10, 12, 14 and 16 birds per cage.
Two White Leghorn strains were used. Statistical
analyses Of weights taken at 6, 12 and 16 weeks Of age
indicated a definite relationship between body weight
and density but the difference was most apparent at 16
weeks Of age. A comparison Of 12 week weights indicated
that identical results would have been Obtained with
either strain.

In trial 3, densities of 6, 8 or 10 pullets in
24 x 24 inch cages were used for the growing period
between 7 1/2 and 15 1/2 weeks Of age. The birds were

not debeaked in this trial. Besides density, feeder

 

 

18

space levels Of 1, 2, 2.4, 3 and 4 inches per bird were
compared._ A back-to-back double deck cage arrangement
was used and feeding was done by a mechanical feeder.
Weights were taken only at 15 1/2 weeks of age, at which
time the pullets were moved. Though body weights tended
to decrease as cage density increased, no real differences
were Observed except for interaction Of feeder space and
cage density. The birds in the lowest density cages pro—
vided with four inches Of feeder space per bird weighed
significantly more than the birds in the highest density
cages provided with only one linear inch Of feeder space
per pullet. All other combinations showed essentially

no difference in body size.

Trial 4 repeated the experimental conditions Of
trial 3 except that the growing period extended from 7 to
18 weeks Of age. The results Of this test showed no
significant differences in body weights Of birds due tO
density or feeder space treatments even though body
weights tended to decrease with decreased feeder spaces.
Bell (1969) stated that "within sensible ranges, these
differences are so slight that they would be extremely
difficult to pick up under commercial conditions"°

Massey and NOles (1968) studied the performance
Of pullets caged in groups with body weights either

within a one-fourth pound range or at random. The results

19

indicated that separation of White Leghorn pullets by

weight is not economical. Lighter weight birds housed
at weights below 1.25 kgs. (2.75 pounds) matured at a

later date and laid fewer eggs than heavier birds.

Almquist (1954) in a review Of applicable research
regarding the phosphorus needs Of chicks concluded that
the readily available phOSphorus requirements for the
chick to four weeks Of age suggests a minimum Of 0.45
percent, in the presence Of ample amounts Of vitamin D.
After this age, he concluded that the requirement may
drOp to 0.35 percent for the period up to 10 weeks.

Very little information has been published by
researchers who compared the egg production of pullets
reared on diets which contained varied levels Of phos-
phorus. However, Temperton gt_al. (1965a) Observed that
pullets reared to 18 weeks Of age on diets which contained
nO feed stuffs Of animal origin and without phosphorus
supplementation showed no significant differences in egg
production during the subsequent laying stage from that
Of similar pullets fed growing diets that contained animal
protein and added phOSphorus as recommended by the National
Research Council of America (1960).

These same researchers, Temperton, et_al. (1965b),
in another test fed pullets diets which contained 0.46 and

0.14 percent available phosphorus, respectively, during

20

the period from day-Old to 8 weeks and 0.40 and 0.12
percent available phOSphorus, respectively, from 8 weeks
Of age tO 18 weeks Of age. They reported that there were
no significant differences in mortality, growth, feed
consumption, nor in feed efficiency between birds fed the
basal growing diet composed of feed stuffs Of plant
origin and birds fed a diet supplemented with inorganic
phosphorus. These researchers found nO advantage when
the starter diet was supplemented to give 0.81 percent
total phOSphorus, 0.35 percent inorganic phosphorus and
0.49 percent available phosphorus. Similarly, they
Observed no effect when the growing diet was supplemented
to provide levels Of total phosphorus that ranged from
0.49 to 0.73 percent; inorganic phosphorus from 0.09 to
0.34 percent; and available phosphorus from 0.20 to 0.5
percent. However, bone ash was reduced in the pullets

grown on the unsupplemented diets.

OBJECTIVES

Experiment 1

The Objectives Of this experiment were:

To compare four replacement pullet rearing conditions,
1 through 4, listed below with respect to (A) effect
on body weight at 7 and 20 weeks Of age, total feed
consumption and mortality and (B) effect on subse-
quent production for six 28-day production periods

in single bird cages, number Of days tO 50 percent
production, laying mortality, egg weight and quality

dimensions in Haugh Units (Haugh, 1937, and Haver e;

31,, 1964), and shell thickness—-

(1) pullets reared in cages from day-Old to 20 weeks
Of age and fed a diet which contained no coccid-
iostat from day—Old to 14 weeks Of age;

(2) pullets reared in cages from day-Old to 20 weeks
Of age and fed a diet which contained a coccid-
iostat from day-Old to 14 weeks Of age;

(3) pullets reared on the floor from day—Old to 7
weeks Of age, in cages from 7 weeks Of age tO
20 weeks Of age, and fed a diet which contained

a coccidiostat from day-Old to 14 weeks Of age;

21

22

(4) pullets reared on the floor from day-Old to 20
weeks Of age and fed a diet which contained a
coccidiostat from day-Old to 14 weeks Of age.

2. TO compare the effect Of five levels Of available

phosphorus, 1 through 5, i.e., (l) 0.16, (2) 0.31,

(3) 0.46, (4) 0.61, and (5) 0.77 percent, in diets

fed to replacement pullets from day-Old to 20 weeks

Of age with respect tO the criteria stated in Objec—

tive l.

3. TO compare the effect Of four rearing conditions and
five levels Of available phosphorus combinations in
diets fed tO replacement pullets for the criteria

listed in Objective 1.

Experiment 2

The Objective Of this experiment was: to compare
four replacement pullet cage rearing density levels, 1
through 4, listed below with respect to (A) effect on body
weight at 7 and 20 weeks of age, total feed consumption and
mortality and (B) effect on subsequent production for six
28~day production periods when housed at single and two
birds per cage densities——

(l) pullets reared in cages at a density Of 10 birds
per cage (day-Old tO 7 weeks Of age) and 5 birds

per cage (7 weeks tO 20 weeks Of age);

 

23

(2) pullets reared in cages at a density Of 20 birds

(3)

(4)

per cage (day-Old to 7 weeks Of age) and 10 birds
per cage (7 weeks tO 20 weeks Of age);

pullets reared in cages at a density Of 30 birds per
cage (day-Old to 7 weeks Of age) and 15 birds per
cage (7 weeks tO 20 weeks Of age);

pullets reared in cages at a density Of 40 birds per
cage (day-Old to 7 weeks Of age) and 20 birds per

cage (7 weeks to 20 weeks Of age).

HYPOTHESES

Experiment 1

(l)

(2)

(3)

H:

There is no difference among rearing conditions
with respect to their effect on body weight,

egg production and egg quality.

There is no difference among diets with reSpect
to their effect on body weight, egg production
and egg quality.

Rearing conditions and diet are independent with
respect to their effect on body weight, egg

production and egg quality.

Experiment 2

(l)

(2)

(3)

H:

There is no difference among rearing density
treatments with reSpect to their effect on body
weight, egg production and egg quality.

There is no difference among laying density
treatments with respect to egg production and
quality.

Rearing density and laying density treatments
are independent with respect to their effect

on egg production and egg quality.

24

MATERIALS AND METHODS

Experiment 1

 

Procedure

 

A total Of 1,767 commercial White Leghorn—type
pullet chicks was divided into five weight classes
numbered 1 to 5: 35 to 36, 37 to 38, 39 to 40, 41 to 42
and 43 to 44 grams, respectively. Chicks with body
weights beyond these limits were discarded.' The chicks
were dubbed at the hatchery but no debeaking was done
throughout this series Of trials. A total of 1,500
pullets was selected and banded. Four chicks from each
weight class were selected at random, wing-banded and
combined to make up replicates consisting Of 20 pullets
each. Two birds from each weight class were randomly
designated to be retained for the 7 tO 20 week rearing
period, one Of which was randomly designated for the sub-
sequent production test.

Five levels Of phosphorus and four rearing systems
were factorially combined for a total Of 20 treatment
combinations. Three replicates Of 20 birds each were

assigned tO each treatment combination. The available

25

26

phosphorus levels were: 0.16, 0.31, 0.46, 0.61 and 0.77
percent. The phosphorus levels were designated Diet 1
through 5, respectively. Composition Of the rearing diets
used in this experiment is shown in Tables 1, 2 and 3. The
rearing systems compared were: (1) in rearing cages from
day-Old tO 20 weeks Of age and fed a diet without a coccid-
iostat; (2) in rearing cages from day-Old to 20 weeks Of age
and fed a diet with a coccidiostat; (3) floor brooding from
day-Old tO 7 weeks Of age and then rearing cages tO 20 weeks
Of age and fed a diet with a coccidiostat; (4) floor brood—
ing and rearing from day—Old to 20 weeks Of age and fed a
diet with a coccidiostat. The coccidiostat was fed to the
birds according tO the manufacturer's recommendations.1
Each treatment replicate group started in cages at day-Old
was assigned at random to one Of 30 cages. The cage size
used was 24 inches wide, 22 inches deep and 16 inches high,
with a one inch x one inch wire grid permanent bottom. A
removable false bottom, one—half inch x one inch wire grid,
was used for the first seven weeks, after which it was
removed. A 24 inch feed trough was provided at the front
Of each cage. The height Of the trough was adjusted as

needed tO allow chicks access tO feed.

 

lAmprol Plus, manufactured by Merck and Company,
Inc., Rahway, New Jersey.

27

Table 1. Starting and growing diets fed tO replacement
pullets from day—Old to 7 weeks Of age,
EXperiment 1.

 

 

 

Diet number: 1 2 3 4 5

%
Corn, yellow 53.67 53.00 52.30 51.60 50388
Soybean meal (50%) 28.03 28.15 28.30 28.45 28.60
Oats 7.50 7.50 7.50 7.50 7.50
Alfalfa meal (17%) 2.50 2.50 2.50 2.50 2.50
Dist. dried sol.,

corn (27%) 2.00 2.00 2.00 2.00 2.00
Fish meal (60%) 1.50 1.50 1.50 1.50 1.50
Whey, dried (12%) 1.50 1.50 1.50 1.50 1.50
Tallow, stabilized .50 .70 .90 1.10 1.30
Methionine hydroxy .

analog .05 .05 .05 .05 .05
Limestone 2.10 1.60 1.10 .60 .12
Dical. phos., 26%

Ca., 18% P. None .85 1.70 2.55 3.40
Salt .40 .40 .40 .40 .40
NOPCOSOL M5 Vit.

Min. Premix .25 .25 .25 .25 .25

Calculated analysis:

Crude protein 20.00 20.00 20.00 20.00 20.00
Fat 3.09 3.28 3.45 3.63 3.79
Fiber 5.17 5.17 5.16 5.15 5.13
Calcium 1.007 1.004 1.002 1.000 1.004
Phosphorus:
Total .411 .563 .716 .868 1.020
Available .160 .312 .465 .618 .771

Energy, productive 928 928 927 927 926

 

Table 2.

28

to 14 weeks Of age, EXperiment 1.

Growing diets fed to replacement pullets from 7

 

 

 

Diet number: 1 2 3 4 5

% % % % %
Corn, yellow 61.62 60.86 60.17 59.46 58.75
Soybean meal (50%) 19.53 19.69 19.83 19.97 20.12
Oats 10.00 10.00 10.00 10.00 10.00
Alfalfa meal (17%) 2.50 2.50 2.50 2.50 2.50
Dist. dried sol.,

corn (27%) 1.50 1.50 1.50 1.50 1.50
Fish meal (60%) 1.50 1.50 1.50 1.50 1.50
Tallow, stabilized .50 .70 .90 1.10 1.30
Limestone 2.06 1.56 1.06 .58 .09
Dical. phos., 26%

Ca., 18% P. .14 1.04 1.89 2.74 3.59
Salt .40 .40 .40 .40 .40
NOPCOSOL M5 Vit.

Min. Premix .25 .25 .25 .25 .25

Calculated analysis:
Crude protein 16.99 17.00 16.99 17.00 17.00
Fat 3.43 3.60 3.78 3.95 4.13
Fiber 5.10 5.09 5.07 5.06 5.05
Calcium 1.000 .999 .996 1.001 1.002
Phosphorus:

Total .396 .557 .709 .862 1.014

Available .166 .327 .480 .633 .786
Energy, productive 956 955 955 954 953

 

Table 3.

29

20 weeks Of age, EXperiment 1.

Growing diets fed to replacement pullets from 14 to

 

 

 

Diet number: 1 2 3 4 5

% % % % %
Corn, yellow 59.15 58.46 57.77 57.07 56.37
Soybean meal (50%) 11.17 11.31 11.45 11.59 11.73
Wheat middlings,

std. 7.50 7.50 7.50 7.50 7.50
Oats 15.00 15.00 15.00 15.00 15.00
Alfalfa meal (17%) 2.50 2.50 2.50 2.50 2.50
Fish meal (60%) 1.50 1.50 1.50 1.50 1.50
Tallow, stabilized .25 .45 .65 .85 1.05
Limestone 2.13 1.63 1.13 .64 .15
Dical. phos., 26%

Ca., 18% P. .15 1.00 1.85 2.70 3.55
Salt .40 .40 .40 .40 .40
NOPCOSOL M5 Vit.

Min. Premix .25 .25 .25 .25 .25
Calculated analysis:

Crude protein 14.50 14.50 14.50 14.50 14.50
Fat 3.45 3.63 3.80 3.98 4.15
Fiber 5.64 5.63 5.62 5.61 5.60
Calcium 1.005 1.002 1.000 1.001 1.002
Phosphorus
Total .406 .558 .710 .862 1.014
Available .169 .326 .475 .628 .781

Energy, productive 923 922 921 921 920

 

30

Chicks assigned to floor treatments starting at
day-old were assigned to pens 16 feet x 9 feet, 10 inches.
Both cage and floor pens were in windowless, insulated,
force-ventilated houses. Fan covers were not available,
hence, complete light control was not possible.

Heat was provided by one 150 watt, infrared, heat
bulb suspended over each cage for the birds on cage
treatments. Supplemental room heat was provided in the
cage room by a gas brooder and a minimum room temperature
Of 70° F. (21.3°C.) was maintained for the first 7
weeks. Two 150 watt, infrared, heat bulbs were used for
brooding in each floor pen. Linear feeder space per
chick at day-Old was 2.4 inches and floor Space was 2.9
square feet in the floor pens. After seven weeks, when
some Of the pullets were removed, feeder space was in-
creased tO 6.0 inches and floor space tO 7.86 square
feet per bird. Water was provided in one-gallon fountains
for the first three weeks in the floor pens, after which
time automatic fountains were used. One Hart cup was
used tO provide water in each cage. Feeder space for the
caged chicks was 1.2 inches per bird. This cage feeder
space was increased to 2.4 inches per bird after seven
weeks when one-half Of the chicks were removed from each
cage; those birds randomly designated for rearing to 20
weeks Of age in cages and for subsequent production testing

were kept in cages.

31

Continuous lighting, a factor imposed on the
trial by the infrared heat lamps, was used from day-Old
to seven weeks Of age. From seven weeks until 14 weeks
Of age, the day-length was reduced to 14 hours daily.
From 14 weeks Of age to 20 weeks, the day length was
reduced by 1 1/2 hours weekly until a 9 hour daily light
period was Obtained. Light was provided in each floor
pen by one 100 watt, red, incandescent light bulb located
in the center Of the pen at ceiling height (8 feet). An
identical lighting regime was used on birds in the cage
room, where the light was supplied by four incandescent
60 watt, red bulbs at ceiling height, located to distri-
bute the light as equally as possible over the rearing
cages. The lighting period was controlled by an electric
time-clock. A secondary lighting system was provided for
use when it was necessary to Observe or care for the
birds.

The birds were vaccinated for infectious bron-
chitis and Newcastle disease at various dates via the
drinking water. The vaccination program followed was
consistent for all birds in the experiment.

The birds were weighed individually at 4, 7, l4
and 20 weeks Of age. Feed consumption records were kept
and feed was weighed-back at each Of these times, thus

making possible computation Of feed utilization efficiency

32

for each replicate for the age interval between each
weighing. At seven weeks Of age, one-half Of the pullets
in each cage and floor replicate group were discarded
leaving 10 pullets in each cage and/or floor replicate
or 30 pullets in each diet housing treatment combination.

At 20 weeks of age, the pullets designated at
day-Old for the production test were transferred to
individual 8 inch by 16 inch cages. A total of 15
pullets from five weight classes was caged for each Of
the 20 diet housing treatment combinations. At 20 weeks
Of age, the pullets were given 14 hours Of light. The
daily light period was then increased 15 minutes each
week until a maximum light period Of 17 hours was obtained.
All treatment groups received the same Michigan State
University Layer-Breeder Diet throughout the production
period.

Individual cage production records were recorded
five days per week, starting when the caged pullets were
22 weeks Of age. Production records were Obtained for
six 28-day periods. The pullets were weighed at the end
Of each 28-day period and feed consumption records were
Obtained. At this time all the eggs laid for three con—
secutive days were identified by cage number and date,
weighed, broken out and measured for Haugh Unit values
and shell thickness. Egg size and quality measurements

were recorded for each pullet by cage number.

33

The rearing data were analyzed by analysis Of
variance (Snedecor, 1956). Body weights and production
data were evaluated at the Computer Laboratory, Michigan
State University, using a modified version Of the Michigan
State University, Agricultural Experiment Station, STAT
Series Description NO. 13, One-way analysis Of variance
with unequal number Of replications permitted (UNEQl
ROUTINE) Ruble-at al., 1967). The experiment followed a
design prepared by Gill (1967). Duncan (1955) Multiple
Range Tests for group means were used where equal numbers
were Observed. The Duncan Multiple Range Tests as modified
by Kramer (1956) for unequal numbers Of replications were
used where unequal numbers Of Observations were encountered.
A Chi-square test was used in the analysis Of mortality

data (Gill, 1969).

Results

An analysis Of variance Of 7-week pullet weights,
Experiment 1 is shown in Table 4.

The 7—week mean body weight Of pullets grown under
the four rearing treatments in Experiment 1 are shown in
Table 5. The average weights for the four rearing condi—
tions, 1 through 4, were 531.50, 510.18, 527.45 and 528.30
grams, respectively. Pullets grown to 7 weeks Of age in
cages and fed the diet with a coccidiostat were signifi—

cantly lighter in body weight (P < 0.01) than those grown

34

Table 4. Analysis Of variance Of 7-week pullet weight,
.Experiment 1.

 

 

 

Source Of Degrees Of Sum Of Mean F
variance freedom squares square ratio
Total 599 1,715,097

Rearing 3 42,115 14,038 10.013**
Diet 4 382,685 95,671 68.239**
Replicates 2 16,380 8,190 5.842**
Weight (class) 4 120,134 30,034 21.422**
R x D 12 27,942 2,328 1.661
R x W 12 291,493 24,291 l7.326**
D x W 16 70,057 4,378 3.123**
Error 546 765,291 1,402

 

**Significant at the 0.01 level Of probability.

Table 5. Seven—week pullet weight by rearing method,
Experiment 1.

 

 

 

Mean body

Rearing method weights (gms)
Cages (day-Old to 20 weeks) fed a

diet without a coccidiostat 531.50 a
Cages (day—Old tO 20 weeks) fed a

diet with a coccidiostat 510.18 b
Floor (day-Old to 7 weeks) fed a

diet with a coccidiostat and
Cages (7 tO 20 weeks) combination 527.45 a
Floor (day—Old to 20 weeks) fed a

diet with a coccidiostat 528.30 a

 

lMeans not followed by a common letter are signif—
icantly different (P < 0.01) when compared by Duncan
Multiple Range test.

35

under the other rearing regimes. The mean body weight Of
birds grown under rearing regimes l, 3 and 4 were not sig-
nificantly different from each other. _At 7 weeks Of age,
the mean body weights for birds on the five diets, 1 through
5, were 474.5, 532.5, 541.7, 541.2 and 531.7 grams, respec-
tively (Table 6). (Pullets fed diet 1 were significantly

lighter than birds fed the other four diets.

Table 6. Seven-week pullet weights by diets, Experiment 1°

 

 

 

Mean body
weights
Diet (available phosphorus level %) (gms.)l

l (0.16) 474.5 a
2 (0.31) 532.5 b
3 (0.46) 541.7 b
4. (0.61) . 541.2'b
5 (0.77) 531.7 b

 

lMeans not followed by a common letter are signif—
icantly different (P < 0.01) when compared by Duncan
Multiple Range test.

According tO initial weight class interval
(Table 7), pullets in class 1 (35 tO 36 grams) were sig-
nificantly lighter in body weight than those in classes

2 and 3. The pullets in weight classes 2 and 3 were not

36

significantly different from each other but were signifi—
cantly lighter in body weight than those in classes 4 and 5.
The mean body weights Of pullets in classes 4 and 5 were not

significantly different from each other.

Table 7. Seven-week pullet weights by weight classes,
Experiment 1.

 

 

 

Mean body
weights
Weight ranges (grams body weight at day-Old) (gms.)
l (35 tO 36 grams) 500.8 a
2 (37 tO 38 grams) 520.4 b
3 (39 to 40 grams) 523.7 b
4 (41 tO 42 grams) 534.2 c
5 (42 to 43 grams) ‘ 542.7 c

 

lMeans not followed by a common letter are signif-
icantly different (P < 0.05) when compared by Duncan
Multiple Range test.

The interaction between rearing regime and diet for
7—week mean body weight was not significant (Table 4). How—
ever, there were significant differences between weights Of
pullets in different replicates. The interaction between
rearing and initial body weight class interval and between
diet and initial weight class interval were highly signif-

icant.

37

The analysis Of variance Of 20 week body weights,
Experiment 1, is shown in Table 8. Rearing and weight
class effects significantly affected body weights at 20
weeks, but the effects of replicates and diets were not

Significant.

Table 8. Analysis Of variance of 20-week pullet weights,
Experiment 1.

 

 

 

Source Of Degrees Of Sum of Mean F
variance freedom squares; square ratio
Total 581 22,157,833

Rearing 3 2,078,999 693,000 21.130**
Diet 4 30,721 7,680 .227
Replicates 2 22,767 11,384 .342
Weight (class) 4 1,396,655 349,164 10.646**
Error 568 18,628,691 32,797

 

**Significant at the 0.01 level Of probability.

The 20-week mean body weights, the average feed
consumption per bird and the percent mortality for each
treatment group are shown in Table 9. The pullets grown
on the floor from day-Old to 20 weeks of age were sig-
nificantly lighter (P < 0.05) in body weight than those
in the other rearing treatments. The mean body weights
for birds on rearing methods,l through 4,were 1728, 1601,

1605, and 1474 grams, respectively.

38

Table 9. Twenty—week pullet weights, feed consumption and
mortality, EXperiment l.

 

 

Mean body Feed

 

weightsl 0-20 weeks Mortality2

Rearing Method (gms.) (kgs.) (%)
Cages (day-Old to 20

weeks without a

coccidiostat) 1728 a 7.922 a 1.33
Cages (day-Old to 20

weeks with a

coccidiostat) 1601 a 7.895 a 2.00
Floor (day-Old to 7

weeks) with a

coccidiostat and
Cages (7 to 20 weeks),

(combination) 1605 a 8.099 b 5.33
Floor (day-Old to 20

weeks) with a

coccidiostat 1474 b 6.991 c 6.66

 

lMeans under same heading not followed by a common
letter are significantly different (P < 0.05) when compared
by Kramer Modification Of Duncan Multiple Range test.

2There were significant differences among the

rearing methods in mortality when the data were subjected to
a Chi-square test (P < 0.05).

The average amount of feed consumed per bird
according to rearing methods 1 through 4 were 7.922, 7.895,
8.099 and 6.991 kilograms, respectively. The floor-reared
pullets consumed significantly (P < 0.05) less feed per
bird to 20 weeks Of age than did pullets reared under the

Other treatments. The pullets grown under the combination

39

Of floor and cage rearing required significantly (P < 0.05)
more feed per bird than did those grown under the other
systems. The two cage rearing systems ranked second in
the amount Of feed used and although the caged pullets
fed the diet without a coccidiostat used slightly more
feed than those fed the coccidiostat, the difference in
feed consumption was not statistically significant. The
mortality for rearing regimes, 1 through 4, were 1.33,
2.00, 5.33 and 6.66 percent, respectively. There were
significant differences among the rearing methods in
mortality when the data were subjected to a Chi-square
test (P < 0.05).

Twenty-week mean pullet weight, feed consumption
per bird, and mortality for birds fed the five diet treat-
ments are shown in Table 10. NO significant differences
in mean body weight were Observed between and among birds
on different diet treatments. The pullets fed diet 1
consumed significantly less feed (P < 0.05) than those
fed diet 2. However, the average amount Of feed consumed
by pullets on neither Of these diets was significantly
different from the amount consumed by pullets on the other
three diets. The feed consumption per bird, diets 1
through 5, were 7.600, 7.845, 7.736, 7.791 and 7.664

kilograms, respectively.

40

Table 10. Twenty—week pullet weights, feed consumption
and mortality by diet, Experiment 1.

 

 

 

(Available Mean body Feed 2

phosphorus weightsl 0-20 weeks Mortality
Diet 1evel%) (gms.) (kgs.) ’(%)
1 (0.16) 1546 a 7.600 a 3.75
2 (0.31) 1608 a 7.845 b 3.75
3 (0.46) 1579 a 7.736 ab 3.75
4 (0.61) 1578 a 7.791 ab 3.75
5 (0.77) 1578 a 7.664 ab 4.10

 

lMeans under same heading not followed by a common
letter are significantly different (P < 0.05) when com—
pared by Kramer Modification Of Duncan Multiple Range test.

2Differences in mortality among the rearing methods

were not significant (P > 0.05) when the data were
subjected to a Chi-square test.

Although the Observed differences in mean body
weight Of birds on the different diets were not statisti—
cally significant, pullets grown on diet 1 were lightest,
averaging 1546 grams. The pullets fed diet 2 had the
heaviest average body weight Of 1608 grams. Little, if
any, difference was Observed among birds fed diets 3, 4,
and 5, with mean body weights Of 1579, 1578 and 1578
grams, reSpectively. Diet 3 (with 0.46 percent available
phosphorus) was formulated tO meet the requirements of

the National Research Council Of America (1964).

41

The mean body weight Of pullets at 20 weeks Of
age by weight class interval are shown in Table 11.
Pullets in class 1 with individual initial weights Of 35
or 36 grams had a mean 20-week body weight Of 1496 grams
and were significantly lighter (P < 0.05) than those in
any Of the other treatment groups. Pullets in classes
2 (37 tO 38 grams) and 3 (39 tO 40 grams) had mean 20-
week body weights Of 1579 and 1563 grams, reSpectively,
and while not significantly different from each other,
they differed significantly from those in classes 1, 4
and 5. The mean 20-week body weight Of pullets in
classes 4 (41 to 42 grams) and 5 (43 to 44 grams) were
the heaviest at 20 weeks (1628 and 1627 grams, respec—

tively).

Table 11. Twenty-week pullet weights by weight class,
Experiment 1.

 

 

 

Mean body
weights1
Initial weight class interval (gms.)

l (35 tO 36 grams) 1496 a

2 (37 to 38 grams) 1579 b

3 (39 to 40 grams) 1563 b

4 (41 to 42 grams) 1628 c

5 (43 to 44 grams) 1627 c

 

lMeans not followed by a common letter are sig-
nificantly different (P < 0.05) when compared by Kramer
Modification Of Duncan Multiple Range test.

42

The results Of the production phase of Experiment
1 are presented in Tables 12 and 13. Table 12 shows the
days Of age at 50 percent production, hen-housed and hen-
day production, percent mortality and feed efficiency for
the four rearing methods tested. Table 13 shows informa-
tion for the same traits shown in Table 12 by diet.

Pullets grown in cages from day-old to 20 weeks
and fed the diet without a coccidiostat reached 50 percent
production significantly earlier than those grown under
the other systems. The number Of days to 50 percent pro-
duction for the females for rearing methods, 1 through 4,
were 163, 167, 168 and 167, respectively. There were no
significant differences in hen-housed egg production,
hen-day egg production, mortality, nor in feed efficiency
among pullets from the four rearing treatment groups.
The pullets grown in cages and fed the ration without a
coccidiostat had the lowest hen-housed and hen-day egg
production (62.4 and 65.1 percent, respectively) as well
as the second highest mortality (8 percent). Pullets
grown in cages and fed the diet with a coccidiostat
(Rearing Method 1) had the highest hen-housed production
(66.2 percent) and, along with the floor-reared birds, had
the lowest laying house mortality (6.7 percent). The
pullets reared under the combination Of floor rearing

from day-Old tO 7 weeks and cage rearing from 7 weeks

43

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44

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45

tO 20 weeks, had the highest hen-day production (68.5
percent) and also the highest laying house mortality (14.7
percent). The pullets grown in cages from day-Old to 20
weeks Of age and fed the diet with a coccidiostat (Rearing
Method 2) had the lowest feed conversion ratio (1.74 kilo-
grams Of feed). The ratio of feed per dozen eggs for
Rearing Methods 1 through 4 were 1.91, 1.74, l.93,and 1.96
kilograms, respectively.

The number Of days to 50 percent production, 168
day hen-housed and hen-day percent production, laying
house mortality and feed efficiency by diet treatments are
shown in Table 13. The average number of days tO 50 per-
cent production for pullets which had been fed diets 1
through 5 were 170, 166, 161, 166 and 169, respectively.
Regarding days to 50 percent production, pullets which had
been fed diets l, 2, 4,and 5 were not significantly
different from each other but those which had been fed
diets l and 5 required a significantly longer period than
those fed diet 3 to achieve this level of production.
However, no significant differences for this trait were
Observed between the pullets which had been fed diets 2,
3,and 4. Pullets which had been fed diet 2 had the highest
hen-housed egg production (68.3 percent). Those which had
been fed diet 4 had the second highest hen-housed produc-

tion (65.0 percent). Hen-housed production for pullets.

46

from diets 3,and 5 was 63.4 and 63.5 percent, respectively.
The differences in egg production were not significant.
The hen-day production for birds fed diet 1 through 5 was
66.4, 71.4, 69.0,and 64.6 percent, respectively. Laying
house mortality for the diet levels 1 through 5 were 13.3,
6.7, 13.3, 6.7,and 6.7, reSpectively. NO significant
differences in mortality due to diet level were found when
the data were subjected to a Chi-square test (P > 0.05).
The feed efficiency for the birds on the diets 1 through

5 was 1.98, 1.76, 1.86, l.9l,and 1.91 kilograms,
respectively.

Simple correlations made with the use Of the
computer facilities at Michigan State University indicated
that body weights at 20 and at 22 weeks Of age were not
associated with average performance during the first three
months of production.. Traits compared were number Of eggs,

egg size, Haugh Unit and shell thickness values.

Experiment 2

 

Procedure

The equipment used in Experiment 2 was essentially
the same as in Experiment 1; however, only cages were
used for rearing during the growing phase. Further, the
removable false bottom Of the rearing cage was bent tO

allow more clearance between it and the permanent cage

47

floor to eliminate the build-up Of droppings that had been
Observed in field testing Of the original type cage. This
condition, however, had not been a problem in Experiment 1.

The purpose Of Experiment 2 was to evaluate the
effect Of cage density during rearing on the subsequent
performance Of pullets housed in laying cages at densities
Of one and two birds per cage during the production period.
Pullets were reared from day-Old tO seven weeks Of age at
densities,l through 4, Of 10, 20, 30 and 40 chicks per
cage, respectively, thus providing 52.8, 26.4, 17.6 and
13.2 square inches Of cage floor area, respectively. At
seven weeks Of age, one-half Of the birds were removed
and placed in identical cages, thus doubling the original
cage floor area per bird for the balance of the growing
period to 20 weeks Of age.

White Leghorn-type commercial pullet chicks were
separated into three weight class intervals: 35 to 37,
38 to 40, and 41 to 43 grams and designated weight classes
1, 2 and 3, respectively. Equal numbers Of chicks from
each weight class were wing-banded for each rearing density
level. The chicks were not dubbed nor debeaked. Six
replicates Of 10 birds per rearing cage were allocated tO
each Of the other three densities. A total Of 330 chicks
was used. The pullets in all treatment groups were fed

the diet number 3 feeding regime as shown in Table l

48

(day-Old to 7 weeks), Table 2 (7-14 weeks) and Table 3
(14-20 weeks). ~A11 birds were weighed to the nearest gram
and replicate feed consumption records were Obtained at 4,
7, l4 and 20 weeks Of age. Mortality data were Obtained
for each density treatment group.

Only one Hart cup for drinking water and the 24
inch feeder trough were permitted per cage regardless Of
population density. Thus, linear feeder space per chick
for the period from day-Old to 7 weeks Of age was 2.5, 1.2,
0.8 and 0.6 inches for the four rearing density levels,
respectively.

When the pullets were weighed at 20 weeks Of age,
those within each treatment group were separated according
to initial body weight class interval. Six pullets from
each weight class (a total Of 18 pullets from each rearing
density) were housed in 18 single bird laying cages; the
same cages that had been used in Experiment 1. Twelve
pullets from each initial weight class (a total Of 36 birds
from each rearing treatment) were housed at a density level
Of two birds per laying cage. Birds from the same initial
weight class were caged together.

Starting at 20 weeks Of age, all Of the pullets
selected for the laying test received the same standard
Michigan State University Layer-Breeder Mash for the dura-

tion Of the experiment. Starting at 22 weeks Of age, egg

49

production data were Obtained for each cage, five days per
week. ,Egg production, body weight and feed consumption
data were Obtained for six 28—day production periods.

Analysis Of body weight and egg production data
were made according tO the experimental design prepared
for this trial (Gill, 1968). Comparisons of treatment
means were made as in Experiment 1.

:All dead birds were examined at the Michigan State

University Veterinary Diagnostic Laboratory.

Results

Analyses Of variance Of the 7-week and 20-week
body weights (Experiment 2) are shown in Tables 14 and
15, respectively. The 7-week and 20-week mean body weight,
feed consumption and mortality are presented in Tables 1
through 4 (which provided 52.8, 26.4, 17.6 and 13.2 square
inches Of cage floor area) at seven weeks Of age were 553,
530, 499 and 479 grams, respectively. Body weight decreased
as cage density increased. The pullets reared at density
level 4 were significantly smaller than those reared at
density levels 1 and 2 but not significantly different
in body weight from the birds reared at density level 3
at 7 weeks Of age. The pullets reared at density levels
1, 2 and 3 were not significantly different from each other

at 7 weeks Of age. The mortality for pullets reared at

50

density levels 1 through 4 were 3.3, 0.0, 3.3 and 7.5,
respectively. NO significant differences in mortality due
to density level were found when the data were subjected tO

a Chi-square test (P > 0.05).

Table 14. .Analysis Of variance Of seven week body weights,
Experiment 2.

 

 

 

Source Of Degrees Of Sum Of Mean F
variance freedom squares square ratio
Total 215 1,001,136

Weight (class) 2 4,798 2,399 0.612
Treatment 3 172,815 57,605 l4.689**
Error 210 823,523 3,922

 

**Indicates significance at the .01 level.

Note: Only seven week body weights Of pullets selected for
the subsequent production test were used in this
analysis.

Table 15. Analysis Of variance of 20—week body weights,
Experiment 2.

 

 

 

Source Of Degrees Of Sum Of Mean F
variance freedom squares square ratio
Total 278 7,435,796

Treatment 3 3,568,685 1,189,562 87.91**
Weight (class) 2 172,978 86,489 6.39**
-Error 273 3,694,133 13,532

 

**Indicates significance at the .01 level.

51

The average feed consumption Of pullets in density
levels 1 through 4 from day-Old to 7 weeks Of age was
1.689, 1.457, 1.404 and 1.284 kilograms, respectively,
Table 16. The pullets in density level 4 were not only
smaller than the pullets reared in density levels 1, 2 and 3
but, also,_consumed signficantly (P < 0.05) less feed than
the pullets reared in density levels 1 and 2. The feed
consumption Of the pullets in density levels 2 and 3 did
not differ significantly. The pullets in density level 1
consumed significantly (P < 0.05) more feed than the

pullets brooded in any of the other density levels.

Table 16. Comparison Of mean body weights, feed used and
mortality for pullets by initial rearing density
at seven weeks Of age, Experiment 2.

 

1L

Mean Mean feed

 

Initial rearing body weights consumption Mortality2
density (gms.) (kgs.) (%)
1(52.8 sq. in./chick
0 to 7 weeks) 553 a 1.689 a 3.3
2(26.4 sq. in./chick
0 to 7 weeks) 530 a 1.457 b 0.0
3(17.6 sq. in./chick
0 to 7 weeks) 499 ab 1.404 bc 3.3
4(13.2 sq. in./chick
0 to 7 weeks) 479 b 1.284 c 7.5

 

lMeans under same heading not followed by a common
letter are significantly different (P < 0.05) when compared
by Duncan Multiple Range test."

2NO significant differences in mortality due to
rearing density level were found when the data were sub-
jected to a Chi-square test (P > 0.05).

52

Table 17. Comparison Of mean body weights, feed used and
mortality for pullets by rearing density at 20
weeks Of age, Experiment 2.

 

 

 

Mean Mean feed
Initial rearing body weights consumption Mortality '
density (gms.) (kgs.) (%)

1(52.8 sq. in./chick

0 to 7 weeks) 1,512 a 8.989 a 10.00
2(26.4 sq. in./chick

O to 7 weeks) 1,472 ab 8.080 b 6.67
3(17.6 sq. in./chick

0 tO 7 weeks) , 1,432 b 8.165 b 15.55
4(13.2 sq. in./chick

0 to 7 weeks) ' 1,321 c 7.421 b 16.67

 

lMeans under same heading not followed by a common
letter are significantly different (P < 0.05) when compared
by Kramer Modification Of Duncan Multiple Range test.

2NO significant differences in mortality due to
rearing density level were found when the data were sub-
jected to a Chi-square test (P > 0.05).

3Marek's Disease and Leukosis were diagnosed as

the cause Of 100 percent Of the mortality during the pro-
duction period.

At 20 weeks Of age, the mean body weights for
birds at the density levels 1 through 4 were 1.512, 1.472,
1.432 and 1.321 kilograms, respectively. As shown, feed
consumption increased as density levels decreased. The
quantities Of feed consumed by the pullets in density
treatments 1 through 4 were 8.989, 8.080, 8.165 and 7.421
kilograms, respectively. However, only the pullets in

density level 1 consumed significantly more feed than the

53

pullets in the other treatment groups. The feed
consumption of pullets at density levels 2, 3 and 4 did
not differ significantly.

The mortality by level (1 through 4) was 10.0,
6.67, 15.55 and 16.67 percent, respectively, but the
differences were not significant. The pullets in cages
with 30 and 40 chicks, density levels 3 and 4, respectively,
had the highest mortality. Marek's Disease and leukosis
were diagnosed as the cause of 59.1 percent of the rearing
mortality from day-old to 20 weeks of age.

Data obtained during the subsequent production
period of pullets reared at density levels 1 through 4,
housed in single bird cages, are presented in Table 18.
The average egg production (survivors) and hen-day produc-
tion data were evaluated by analysis of variance. There
were no significant differences found. The number of days
to 50 percent production as calculated on a group basis
for the pullets in density levels 1 through 4 was 178, 175,
175 and 173 days, respectively. The pullets reared at
density level 4 reached 50 percent production slightly
before (5 days) those reared at other levels. The pullets
reared at the lowest density required the longest period
of time to reach 50 percent production. The mean number
of eggs for pullets surviving the six 28—day production

periods was 79.1, 82.2, 83.0 and 79.4 for the density levels

54

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55

1 through 4, reSpectively. Hen-day production percentages
were 60.3, 65.2, 61.6 and 62.5, respectively. The
mortality of the pullets by density level 1 through 4 was
22.2, 16.7, 16.7 and 22.2, respectively. No significant
differences in mortality due to rearing density level were
found when the data were subjected to a Chi-square test
(P > 0.05). Marek's Disease and leukosis were diagnosed
in all cases of mortality from the birds caged individually.
Production data for the pullets housed at a density
of two birds per cage are shown in Table 19. The number of
days to 50 percent production by density levels, 1 through
4, was 173, 182, 182 and 179, respectively. The birds
reared at the lowest density reached 50 percent production
somewhat sooner than the pullets grown at the higher
density levels. However, pullets reared at the densities
tested reached 50 percent production at about the same
time irrespective of rearing density. The mean number of
eggs laid per pullet, by density levels 1 through 4, was
80.0, 80.0, 80.8 and 68.9, respectively. The pullets
reared at the highest density level laid the fewest eggs.
The hen-day production for the birds in density levels 1
through 4 was 65.5, 66.2, 54.6 and 55.4 percent, reSpec-
tively. The egg production of the pullets reared at the
relatively higher densities (3 and 4) was significantly

lower than that of those reared at levels 1 and 2. The

56

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57

hen-housed production reflects the effect of mortality on
production--55.l, 64.0, 49.5 and 47.9 percent for density
levels 1 through 4, respectively. The mortality of the
birds in the four density groups was 23.5, 11.1, 25.7 and
25.0 percent, respectively. However, no significant
differences in mortality due to density level were found
when the data were subjected to a Chi-square test (P >
0.05). Marek's Disease and leukosis were diagnosed in 73
percent of the pullets that died in two bird density cages.
Table 20 shows the hen-day percent production by
initial weight class interval for pullets housed in single
bird cages. Table 21 shows the data for those females
housed two birds per cage. The mean hen-day production
of the pullets housed in single bird cages for weight
class 1 (35 to 37 grams), 2 (38 to 40 grams) and 3 (41 to
43 grams) was 52.0, 70.6 and 65.6 percent, respectively.
The pullets in weight class 1 had significantly lower hen-
day production than those in the other classes tested.
The hen-day percentages for pullets housed at two birds
per cage for initial weight class intervals 1, 2, and 3
were 55.4, 64.6 and 62.4, respectively. Although the
pullets in class 1 had lower production than those in the

other two classes, the differences were not significant.

58

Table 20. Comparison of percent hen—day production of
pullets housed in single bird cages by weight
class, Experiment 2.

 

 

 

 

Production Weight Class Interval (gms.)
l 2 3
(35 to 37) (38 to 40) (41 to 43)
Hen day (percent)l 52.0 a 70.6 b 65.6 b

 

lMeans not followed by a common letter are sig—
nificantly different (P < 0.05) when compared by Kramer
Modification of Duncan Multiple Range test.

Table 21. Comparison of percent hen-day production of
pullets housed at a density of two birds per
cage by weight class, ExPeriment 2.

 

 

 

 

Production Weight Class Interval (gms.)
l 2 3
(35 to 37) (38 to 40) (41 to 43)
Hen day (percent)l 55.4 a ' 64.6 a 62.4 a

 

lMeans not followed by a common letter are sig-
nificantly different (P < 0.05) when compared by Kramer
Modification of Duncan Multiple Range test.

Tables 22 and 23 show data regarding egg weight,
Haugh Unit and shell thickness values for pullets housed
at one and two birds per cage, respectively, according to
rearing density. The mean weights of eggs laid by pullets

housed one bird to a cage for pullets from rearing

59

Table 22. Effect of p0pu1ation density during rearing (0 to
20 weeks of age) on subsequent egg weight and
productiOn quality criteria, of pullets housed at
one bird per cage, Experiment 2.

 

 

 

Mean Mean Shell
Initial rearing egg weight Haugh Unit thickness 1
density (gms) valuel (millimeters)
(52.8 sq. in./chick
O to 7 weeks) 48.4 a 88.0 a .337 a
(26.4 sq. in./chick
O to 7 weeks) 46.6 a 89.1 a .325 a
(17.6 sq. in./chick
O to 7 weeks) 50.2 b 90.1 a .320 a
(13.2 sq. in./chick
O to 7 weeks) 50.3 b 89.8 a .325 a

 

lMeans under same heading not followed by a common
letter are significantly different (P < 0.05) when compared
by Kramer Modification of Duncan Multiple Range test.

Table 23. .Effect of population density during rearing (0 to
20 weeks of age) on subsequent egg weight and
production quality criteria, of pullets housed at
two birds per cage, Experiment 2.

 

 

Mean Mean Shell
Initial rearing egg weight Haugh Unit thickness 1
density (gms) value (millimeters)

 

(52.8 sq. in./chick

0 to 7 weeks) 48.5 a 90.1 a .320 a
(26.4 sq. in./chick

O to 7 weeks) 48.8 a 89.2 a .337 b
(17.6 sq. in./chick

O to 7 weeks) 50.1 a 89.4 a .325 a
(13.2 sq. in./chick

0 to 7 weeks) 49.5 a 88.4 a .320 a

 

lMeans under same heading not followed by a common
letter are significantly different (P < 0.05) when compared
by Kramer Modification of Duncan Multiple Range test°

6O

densities 1 through 4 were 48.4, 46.6, 50.2 and 50.3 grams,
respectively. The pullets reared at the two highest density
levels laid eggs that were significantly larger than the
eggs laid by pullets reared at density levels 1 and 2.
There was little, if any, difference in the size of eggs
from pullets reared at density levels 3 and 4. The mean
average weight of eggs laid by pullets reared at density
level 2 was lowest among all treatment groups but was not
significantly different from eggs laid by the pullets in
density level 1. However, no significant differences were
found among density treatment means for egg weight when the
data from the first three production periods were analyzed
(Table 24).

Mean Haugh Unit values (a measure of interior egg
quality) for eggs laid by pullets from density levels 1
through 4 were 88.0, 89.1, 90.1 and 89.8, respectively.
There were no significant differences in Haugh Unit values
of eggs from pullets reared at density levels 1 through 4,
housed at one bird per cage.

Shell thickness values (an indication of shell
strength, Stewart, 1936), for eggs laid by pullets from
rearing density levels 1 through 4 were 0.337, 0.325, 0.320
and 0.325 millimeters, respectively. An analysis of vari—
ance showed no significant differences among shell thickness

me ans .

61

Table 24. Effect of p0pu1ation density during rearing (0 to
20 weeks of age) on subsequent egg weight and
production quality criteria (average of trait
data for first three production periods) for all
pullets housed.

 

 

 

Mean Mean *Shell
Initial rearing egg weight Haugh Unit thickness 1
density (gms)l valuel (millimeters)
1(52.8 sq. in./chick
0 to 7 weeks) 56.1 a 86.3 a .328 a
2(26.4 sq. in./chick
0 to 7 weeks) 55.3 a 86.1 a .325 a
3(17.6 sq. in./chick
0 to 7 weeks) 56.0 a 87.0 a .325 a
4(13.2 sq. in./chick
0 to 7 weeks) 57.1 a 88.3 a .325 a

 

lMeans under same heading not followed by a common
letter are significantly different (P < 0.05) when compared
by Kramer Modification of Duncan Multiple Range test.

The data in Table 23 include mean egg weights for
pullets from density levels 1 through 4 as follows: 48.5,
48.8, 50.1 and 49.5 grams. The mean Haugh Unit values for
eggs laid by pullets from the four rearing densities in
the same order were 90.1, 89.2, 89.4 and 88.4. Analyses
of variance showed no significant differences among means
regarding either egg weights or Haugh Units. The shell
thickness means for eggs laid by pullets from density
levels 1 through 4 were 0.320, 0.337, 0.325 and 0.320
millimeters, respectively. The shell thickness of eggs

from pullets reared at density 2 (26.4 sq. in. per chick)

62

was significantly greater than the thickness values for
pullets from the other rearing density treatment levels
at the end of the first production period. However, no
significant differences were found among density treatment
means for shell thickness when the data from the first three
production periods were analyzed (Table 24).

Feed efficiency data for the production period are
given in Table 25 by rearing density level and housing cage

density. Feed efficiency by rearing densities 1 through 4

Table 25. Production feed efficiency (kiloqrams of feed
per dozen eggs) by rearing density and housing
cage density, Experiment 2.

 

 

 

 

 

Feed efficiencyl
Initial rearing l bird/cage 2 birds/cage
density (kgs) (kgs)
1 (52-8 sq;,in./Chick
0 to 7 weeks of age) 2.01 1.93
2 (26.4 sq. in./chick
0 to 7 weeks of age) 1.84 1.89
3 (17.6 sq. in./ChiCk
0 to 7 weeks of age) 1.87 2.05
4 (13.2 sq. in./chiCk
0 to 7 weeks of age) 2.07 2.11
1

Differences ianeed efficiency among the rearing
densities were not significantly different (P > 0.05).

63

was 2.01, 1.84, 1.87 and 2.07 kilograms, respectively, for
pullets housed at one bird per cage. Feed efficiency by
rearing densities 1 through 4 for pullets housed at two
birds per cage was 1.93, 1.89, 2.05 and 2.11, respectively.
Differences in feed efficiency of pullets among rearing
densities were not significantly different whether the

birds were housed at one or two birds per cage.

DISCUSSION

The results of Experiment 1 of this study were
generally consistent with the findings of Shupe and
Quisenberry (1961) regarding mean body weight, feed con-
sumption and production of pullets reared on the floor
and in cages, but were different as to mortality. Shupe
and Quisenberry (1961) found that floor reared birds
were significantly lighter in body weight at 22 weeks of.
age than were pullets which had been reared on the floor
to 14 weeks of age and then in colony cages from 14 weeks
to 20 weeks of age. The mean body weight of the floor
reared birds used in the Texas test was 1,809 grams com-
pared to 1,840 grams for the pullets reared in colony
cages. The floor reared pullets consumed an average of
4.404 kilograms of feed compared to 5.321 kilograms for
the colony cage reared birds and mortality was significantly
higher in the cage reared birds. Shupe and Quisenberry
reported that most of the mortality which occurred in the
cage reared birds was due to cannibalism. The mean body
weight of the floor reared pullets (0 to 20 weeks of age)
in Experiment 1 was 1,474 grams compared to 1,728 grams

for the pullets reared in cages and fed a diet with a

64

 

65

coccidiostat, 1,601 grams for the pullets reared in cages
and fed a diet without a coccidiostat, and 1,605 grams
for the floor-cage combination reared birds. The pullets
reared on the floor (0 to 20 weeks of age) weighed sig-
nificantly less than did the pullets reared in cages or
in the floor-cage combination.

In Experiment 1, the average feed consumption of
pullets (0 to 20 weeks of age) by rearing method 1 through
4, i.e., cages-no coccidiostat, cages—coccidiostat, floor-
cage combination and floor rearing method, was 7.922,
7.895, 8.099 and 6.991 kilograms, respectively.

The floor reared pullets consumed significantly
less feed than either the cage reared birds or the floor-
cage combination reared birds (0 to 20 weeks of age).

The floor-cage combination reared pullets consumed sig—
nificantly more feed from day-old to 20 weeks of age than
either the cage reared or floor reared birds. Mortality
of pullets reared by methods 1 through 4 was 1.33, 2.00,
5.33 and 6.66 percent, respectively. Differences in
mortality of pullets among the rearing methods were sig-
nificantly different when the data were subjected to a
Chi—square test (P < 0.05). No cannibalism was observed
among the pullets in any of the rearing methods tested

in Experiment 1.

 

66

Regarding production, the findings of Shupe and
Quisenberry (1961) are consistent with the results of
Experiment 1 to the extent that there were no significant
differences in egg production, egg weight, feed efficiency
or mortality among the pullets reared by the methods
tested. Shupe and Quisenberry observed that production
mortality for floor reared pullets was 13.27 percent
compared to 14.29 percent for the colony cage reared birds
(14 to 22 weeks of age). In the production phase of
Experiment 1, mortality was highest (14.7 percent) in
pullets which had been reared by the floor-cage combina-
tion method. It was lowest (6.7 and 6.7 percent,
respectively) in cage-coccidiostat reared and floor
reared pullets.

The results of Experiment 1 were different from
the findings of Magruder and Nelson (1968) who compared
floor, floor-cage combination and cage rearing of pullets
and found that these rearing methods produced pullets of
about the same mean body weight (1,430, 1,430 and 1,450
grams, respectively) at 21 weeks of age. In Experiment
1, the pullets reared on the floor were significantly
lighter and consumed significantly less feed than the
pullets reared in cages (0 to 20 weeks of age) or in the
floor-cage combination method. Magruder and Nelson

observed that floor reared birds had the lowest rearing

 

67

mortality (0.83 percent, compared to 3.72 and 3.75 percent
for birds reared in the floor-cage combination and cage
rearing methods, respectively). No analysis of mortality
data was reported. They found that mean feed consumption
(0 to 21 weeks of age) for the floor, floor-cage combina-
tion and cage reared birds was 7.50, 7.64 and 7.98 kilo-
grams, respectively, which indicated a trend toward higher
feed consumption among cage reared birds compared to floor
reared pullets. In EXperiment l, cage reared pullets
consumed significantly more feed than did floor reared
pullets. During the production phase, Magruder and Nelson
found that hen-day production of pullets from the floor,
floor-cage and cage rearing methods was 75.7, 74.4 and
74.2 percent, respectively, with little if any difference
in feed efficiency. Hen-day production in Experiment 1
for pullets from the cage-no coccidiostat, cage-
coccidiostat, floor-cage combination and floor rearing
methods was 65.1, 67.6, 68.5 and 67.8 percent, respectively.
The differences in hen-day production were not significant.
Laying house mortality of pullets from the floor, floor-
cage combination and cage rearing methods was 1.8, 1.5 and
1.1 percent, reSpectively in the Magruder and Nelson (1968)
report. No differences in production mortality in Exper-
iment 1 due to rearing methods were found. Magruder and

Nelson reported that production feed efficiency (kilograms

 

 

68

of feed per pound of eggs) for the floor, floor-cage
combination and floor rearing methods was 1.69, 1.65 and
1.65, respectively, which indicated a slight trend toward
higher feed consumption by floor reared birds during the
laying period. This trend was also evident in the data
from EXperiment l.

The conclusion may be drawn by commercial pullet
growers from the data in EXperiment 1 that important
savings in feed cost can be achieved by growing pullets
on the floor. However, pullets reared on the floor appear
to compensate for reduced feed consumption during the
rearing period by consuming more feed during the production
phase than do cage reared birds. It appears from the
results of Experiment 1 that floor rearing from day-old
to seven weeks of age does not significantly affect 20-
week body weight or feed consumption of pullets subse-
quently reared from seven to 20 weeks of age in cages as
compared to the same traits for birds reared in cages
from day-old to 20 weeks of age.

The findings in Experiment 1 regarding the effect
of available phosphorus levels was consistent with the
findings of Temperton et_§1. (1965a and 1965b). No sig-
nificant differences in egg weight or egg quality criteria

attributable to ration fed during rearing were found.

69

The data in Experiment 1 regarding body weight of
pullets at 20 weeks of age suggest that equal performance
may be eXpected from pullets ranging in mean body weight
from 1,474 grams through 1,728 grams. Body weights of
pullets at 20 and at 22 weeks of age were not correlated
with average performance during the first three months
of production. Traits compared were number of eggs, egg
size, Haugh Unit and shell thickness values.

The results of EXperiment 2 regarding the effect
of rearing density were generally consistent with the
findings of Bell (1969) in that mean body weight of
pullets trended downward as cage p0pu1ation was increased.
However, only ageneral comparison for growth of pullets
can be made between the two studies because density-cage
floor space relationships and rearing periods were not
similar. The California trials demonstrated the effect
of crowding and/or limited feeder space during the rearing
period on body weight of replacement_pullets. A signif—
icant difference in body weight was found only where
pullets reared at a density of 10 birds per cage with one
inch of feeder space per chick were compared with pullets
reared at a density of six birds per cage with four inches
of feeder space per pullet. These findings would be some-
what comparable to the results obtained in Experiment 2

where feeder space decreased as density was increased

 

 

70

through density levels 1 to 4, i.e., 10, 20, 30 and 40
pullets per cage with corresponding feeder space of 2.5,
1.2, 0.8 and 0.6 inches, respectively, per 24 inches
wide x 22 inches deep x 16 inches high cage.

The restrictions on cage space and cage feeder
space appear to have resulted in lower mean body weight
of pullets in Experiment 2. The mean body weight of
pullets reared to 20 weeks of age by density levels 1
through 4 was 1,512, 1,472 and 1,321 grams, respectively.
The pullets reared in density 4 were significantly lighter
in body weight than the pullets reared in densities l, 2
and 3. The pullets reared in density 1 consumed signif—
icantly more feed during the rearing period (0 to 20 weeks
of age) than the pullets reared in densities 2, 3 and 4.
Mean feed consumption by pullets in rearing densities 1
through 4 was 8.989, 8.080, 8.165 and 7.421 kilograms,
respectively. The data from Experiment 2 suggest a
positive relationship between cage floor space, feeder
space and body weight at 20 weeks of age. However,
differences in mean number of eggs produced by survivors
(pullets that survived the six 28—day production periods)
by rearing density of pullets housed at either one or two
birds per cage were not significant. However, significant
differences in hen-day production were found among pullets

reared by the density levels tested when the pullets were

 

 

71

housed at two birds per cage but not when they were housed
at one bird per cage. Mean hen-day production for pullets
reared at levels 1 through 4 was 65.5, 66.2, 54.6 and 47.9
percent, respectively. The pullets reared at density levels
3 and 4 had significantly lower hen-day production than did
the pullets reared at density levels 1 and 2. These data
suggest that pullets reared at density levels 3 and 4 and
subsequently housed at two birds per cage were unable to
overcome the limiting effect of high rearing density on
hen-day production when housed at two birds per cage. No
significant differences in mortality due to rearing density
level were found when the pullets were housed at either one
or two birds per cage when the data were subjected to a Chi—
square test (P > 0.05).

The hen-day production by initial weight class
intervals 1 through 3 was 52.0, 70.6 and 65.6 percent,
respectively, when the pullets were housed in single bird
cages. The pullets in weight class 1 (35 to 37 grams) had
significantly lower hen—day production than did the pullets
in weight classes 2 (38 to 40 grams) or 3 (41 to 43 grams)
when housed at one bird per cage but not when housed at 2
birds per cage. .Although Experiment 2 was not designed to
investigate the effect of initial pullet weight on produc-
tion, the data suggest that further work to evaluate the
effect of this trait on subsequent performance may be

worthwhile.

 

 

72

The mean egg weight of pullets reared by density
levels 1 through 4 was 48.4, 46.6, 50.2 and 50.3 when the
pullets were housed at one bird per cage. The mean egg
weight of pullets in densities 1 and 2 was significantly
lighter than that of pullets in densities 3 and 4 at one
bird per cage laying density but not at two birds per
cage.) The higher mean egg weight of pullets reared at
relatively high densities and housed at one bird per
cage suggest that sexual maturity was delayed contributing
to larger egg size; however, this was not the case as the
birds reared at the highest density levels actually
reached sexual maturity as early as those with the greater
floor space allowance.

The significantly higher shell thickness value of
eggs laid by pullets reared at density level 2 (20 birds
per cage, 0 to 7 weeks) and housed at two birds per
cage, suggest that this rearing density may be more
Optimum for this factor than the others tested. However,
additional tests seem in order before a definite conclu-
sion can be drawn. No significant differences in shell
thickness due to rearing method were found when the
pullets were housed at one bird per cage.

It appears, when all factors are considered, that
the optimum density for rearing pullets under the condi-

tions of this experiment may be 20 pullets per cage

 

73

(26.4 sq in./chick) or slightly higher for the first
seven weeks of the growing period.. However, further
tests should be conducted to carefully define the optimum
density. This study was designed to eXplore a wide range
in rearing density levels and the possible relationship
of rearing density to subsequent performance. Variations
in the effect of water and feeder space may well deserve
further study in conjunction with cage density in the
determination of the most efficient density level

associated with economic production.

 

 

SUMMARY

There is a lack of information on the relationship
of management and nutritional aspects of caged pullet
rearing to economic egg production. It was therefore of
interest to evaluate the subsequent performance of pullets
reared under four methods: in cages without a coccidio-
stat in the diet, in cages for the same period with a
coccidiostat in the diet, on litter to seven weeks of age
and then in cages to 20 weeks of age, and on litter to 20
weeks of age. Five levels of phosphorus were factorially
combined with the four rearing methods (20 factorial
combinations). Pullets grown in these combinations were
compared for mean body weight at 20 weeks of age and for
production in single bird density laying cages.

Day-old commercial White Leghorn type pullets
were used in this eXperiment. No debeaking was done.

The pullets reared on the floor were significantly lighter
in weight and consumed significantly less feed than
pullets reared in cages or in the floor-cage rearing
methods. Mortality percentages by rearing method were
1.33 (cages-no coccidiostat), 2.00 (cages-coccidiostat),

5.33 (floor-cage cOmbination), and 6.66 (floor). No

74

 

75

significant differences in body weight at 20 weeks of age
due to diet treatments were found.

The same diet was fed to the birds in all treat-
ment combinations during the production phase. No signi—
ficant differences in performance were found among the
treatment combinations during the production phase
regarding egg production, egg weight, Haugh Unit or shell
thicknessrvalues.

Experiment 2 was conducted to test the effect of
rearing density, i.e., 10, 20, 30, or 40 chicks (density
levels 1 through 4, respectively) per 24 inches wide x
22 inches deep x 16 inches high cage, on performance during
the subsequent production phase.

A total of 330 White Leghorn type day-old pullets
were separated into three weight class intervals that
differed in weight by three grams. Equal numbers of
chicks from each weight class were wing-banded for each
rearing density to be tested. Feeder space per chick
for rearing densities 1 through 4 was 2.5, 1.2, 0.8 and
0.6 inches, respectively. At seven weeks of age, one-half
of the pullets were transferred to identical cages, thus
doubling feeder and cage space for the remainder of the
rearing period to 20 weeks of age.

Fifty-four pullets from each rearing density level

were selected equally from the three weight classes.

76

Eighteen pullets were housed at one bird per cage in 8
inch x 16 inch cages and the remaining 36 were placed in
the same size cages at two birds per cage. All pullets
received the same laying diet. Records of production
were obtained from 22 weeks of age through six 28-day
production periods.

At 20 weeks of age the pullets reared at density
4 were significantly lighter than those reared at the
other densities and had consumed significantly less feed.
The pullets reared at density 1 consumed significantly
more feed than did the pullets in the other treatment
levels.

No significant differences were found among the
means of numbers of eggs laid by pullets surviving the
six 28-day production periods at either one or two birds
per cage laying density. However, there were significant
differences in hen-day production where the pullets were
housed at two birds per cage; whereas no significant
differences were found where they were housed individually.
The pullets reared at density levels 3 and 4 had signif-
icantly lower hen-day production than those reared at
levels 1 and 2. In the first production period, the
pullets reared at density levels 3 and 4 and subsequently
housed at one bird per cage laid significantly larger

eggs than those that had been reared at density levels 1

77

and 2; however- no significant differences were found
for this trait when data from the first three production
periods were analyzed. No significant differences were
found for this factor when the pullets were housed at

two birds per cage.

 

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