110
626

 

THE EFFECT OF DEGREE OF DEBEAKING AND CAGE POPULATION
SIZE ON SELECTED PRODUCTION CHARACTERISTICS OF
CAGED LAYERS

Thesis for the Degree of M. S.
MICHIGAN STATE UNIVERSITY

Robert Carey Hargreaves

'I 965

 

THESIS

LIBRARY

Michigan State
University

 

ABSTRACT
THE EFFECT OF DEGREE 0F DEBEAKING.AND CAGE POPULATION
SIZE ON SELECTED PRODUCTION CHARACTERISTICS OF
CAGED LAYERS

by Robert Carey Hargreaves

Debeaking is commercially used as one method of preventing canni-
balism in young growing chickens, laying hens, turkeys, and game birds.
In recent years, the relative severity of debeaking has increased. The
primary purpose of this experiment was to determine the effects that
severe degrees of debeaking might have on production characteristics of
caged laying chickens.

Single Comb'White Leghorn pullets were debeaked at 18 weeks of age
and placed in l-bird and 3-bird cages. Other birds from the same stock
were debeaked at 24 and 25 weeks of age and placed in 2-bird cages and
21-bird cages. Three degrees of debeaking were used -- 1/2, 3/& and
all of the distance between the tip of the beak and the nostrils. Ap-
proximately the same amount of both upper and lower mandibles was re-
moved. Non-debeaked birds served as the controls. The birds with all
of the beak removed are referred to as "entirely debeaked”.

Compared with birds in any of the other three treatments, entirely
debeaked birds gave poorer results. They took longer coming into egg
production, laid fewer eggs, ate less feed and made smaller body weight
gains. All of these differences were highly significant.

Egg production of birds debeaked 1/2 and 3/& was not significantly
different from that of the controls, but feed consumption of birds de-
beaked 3/% was significantly lower than that of the controls. Differ-

ences in body weight gain were highly significant between the controls

Robert Carey Hargreaves

and birds debeaked 1/2 or S/A. The difference in body weight gain be-
tween birds debeaked 1/2 and S/h was not significant.

In feed efficiency, highly significant interactions between degree
of debeaking and cage population size were found. Birds in entirely
debeaked treatments consumed significantly more feed per dozen eggs than
birds in most other treatments. Birds debeaked 3/& and housed in 21-bird
cages consumed significantly less feed per dozen eggs than birds in most
other treatments. Other differences in feed efficiency were not signif—
icant.

Birds in 1-bird cages laid significantly better than birds in 3-bird
cages and highly significantly better than birds in 21-bird cages. The
birds in 2-bird cages laid significantly fewer eggs than the birds in
any of the other cage population sizes, but this was complicated by
chronic mortality in this group during the initial stages of the exper-
iment.

Birds in l-bird cages ate significantly more feed than the birds in
3-bird cages and 21-bird cages, and the birds in 3-bird cages ate signif-
icantly more feed than birds in 21—bird cages.

There is a need for further research into the physiological basis
for differences observed in this experiment. Practical recommendations,
however, can be made in the light of this research. Debeaking 1/2 to
3/fi of the beak of lB-week-old pullets appears to be a normally safe
practice without any adverse effects. Debeaking more than 3/h, however,
could be disastrous. A significant reduction in egg production and a
significant decrease in feed consumption can be expected in entirely de-

beaked caged layers.

THE EFFECT OF DEGREE OF DEBEAKING AND CAGE POPULATION
SIZE ON SELECTED PRODUCTION CHARACTERISTICS OF

CAGED LAYERS

by

Robert Carey Hargreaves

A THESIS

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

MASTER OF SCIENCE

Department of Poultry Science

1965

ACKNOWLEDGEMENT

The author wishes to thank Dr. L. R. Champion and Dr. T. H.
Coleman for their help and guidance in preparing and carrying out
this research and their critical reviews of this manuscript.

Appreciation for assistance in preparing the statistical anal-
yses used in this study is expressed to Dr. J. H. Stapleton of the
Statistics Department.

Grateful acknowledgement is also expressed to Dr. H. C. Zindel
and Professor J. A. Davidson for providing the funds and materials

necessary for conducting this project.

TABLE OF

I INERODUCTION . . . o . 0

11 REVIEW 0? LITERATURE . . 0

III OBJECTIVES . o . o . . .

IV EXPERIMENTAL PROCEDURE . .

V RESULTS AND DISCUSSION . .

A.

B.

C.

D.

E.

F.

G.

H.

1.

Egg Production .
Days to First Egg
Feed Consumption
Feed Efficiency

Feed wastage . .
Body WBight . .
Beak Length . .
Egg weight . . .

mrt‘lity o o o 0

VI WY AND CDNCLUSIONS .

VII TABLES, GRAPES AND FIGURES

VIII LITERATURE CITED . . . . .

CONTENTS

Page

0 O O O O O O O O O O O O O O O 1
O O O O O O O O O O O O O O O O 2
O O O O O O O O O O O O O O O O 9
O O O O O O O I O O O O O O O O 10
O O O O O O O O O O O O O O O O 13
O O O O O O O O O O O O O O O O 13
O O O O O O O O O O O O O O O O 1“
O O O O O O O O O O O O O O O O 1“
O O O O O O O O O O O O O O O O 15
O O O O O O O O O O O O O O O O 16
C O O O 0 O O O O O O O O O O O 17
O O O O O C O O O O O O O O O O 18
O O O O O O O O O O O O O O O O 20
O O O O O O O O O O O O O O O O 20
O O O O O O O O O O O O O O O O 21
O O O O O O O O O O O O O O O O 2“

LIST OF ILLUSTRATIONS

Illustrations Page

Graph 1. Egg production - percent hen-housed (combined
l-bird, 3"bird and Zl-bird CagGS) e o o o e o e 39

Graph 2. Egg production - percent hen-housed, by cages . . #0

Graph 3. Feed consumption - lbs/bird/day (combined l-bird,
3"bird and Zl-bird cagQS) e o e e s e e o e e e “'1

Graph a. Feed consumption - lbs/bird/day, by cages . . . . #2

Graph 5. Feed consumption - immediate effects of debeaking
iDl‘bi-rdcageseeeoeoeooooooeee“’3

Graph 6. Body weight l-bird cages . . . . . . . . . . . . nu

Graph 7. Body weight

2-birdcage8............‘l5

Graph 8. Body weight 3-bird cages . . . . . . . . . . . . as

Graph 9. Body weight

Zl'bitdcages 00000000000 #7

5

Graph 10. Beak lengths, l-bird cages

Plate 1. Six weeks after debuking o o o e e o e e e e e o “'9
Figure 1. Control
Figure 2. Debeaked 1/2
Figure 3. Debeaked 3/4
Figure 4. Entirely debeaked

Plate II. Twenty weeks after debeaking . . . . . . . . . . . 50
Figure 5. Contra].
Figure 6. Debeaked 1/2
Figure 7. Debeaked 3/h
Figure 8. Entirely debeaked
Figure 9. Entirely debeaked, showing variation
Plate 111. Five hundred days of age . . . . . . . . . . . . . 51
Figure 10. Control
Figure 11. Debeaked 1/2
Figure 12. Debeaked 3/h
Figure 13. Entirely debeaked

Tables
1.
2.
3.
h.
5.
6.
7.
8.
9.

10.

11.

12.
13.
14.
15.
16.
17.
18.
19.

20.

LIST OF TABLES

Experflmental design

Functional Housing Conditions

Cbmposition of diet

Egg production - 20 weeks of lay (25 to an weeks of age)

Total egg production (25 weeks to 500 days of age)

Egg production, 2-bird cages (25 weeks to 500 days of age

Days
Feed
Feed
Feed

Feed
of

Feed
Body
Body
Body
Beak

Beak

to first egg (l-bird cages)

consumption (lbs/bird/day) 25 to an weeks of age
consumption (lbs/bird/day) 25 weeks to 500 days of age
efficiency (lbs/feed/doz. eggs) 25 to an weeks of age

efficiency (lbs/feed/doz. eggs) 25 weeks to 500 days
age

wastage (3-bird cages, an weeks of age)
weight gains (lbs.)

weight averages (lbs.)

weight averages, 25bird cages (lbs.)
length (cm.) l-bird cages

length (cm.) l-bird, 3-bird and 21-bird cages

Average egg weight (gms.) 25 weeks to 500 days of age

Mortality (percent) 25 weeks to M weeks of age

Mortality (percent) 25 weeks to 500 days of age

Page
2h
2h

25

27
28
28
29
29

30

30
31
32
33
3a
35
36
37
38

38

INTRODUCTION

With the development of modern high density laying systems, parti-
cularly multipledbird cages, the problem of cannibalism among laying
hens has become more serious in recent years. The most common method
of dealing with this problem has been to debeak. As cannibalism.in-
creased, the severity of debeaking increased, and it is not unusual
today to find recommendations for debeaking within 1/8 to 1/u inch of
the nostril (Price, 1959; Godfrey, 1960; Davis, 1962; Vandervort, 1962;
Sink, 196“).

There is some question in the minds of many poultrymen as to the
advisability of using such severe debeaking. The present study was
carried out to establish a scientific basis for debeaking recommenda-
tions.

In cages, the severity of cannibalism has generally been observed
to increase as the number of birds per cage is increased and as the
space allowed per bird is decreased. Any study on the efficacy of

debeaking, therefore, should take these factors into consideration.

REVIEW OF LITERATURE

Debeaking Broilers

 

Up to the present time most of the debeaking research has been
conducted with broilers.

The efficacy of debeaking in broilers has been well-demonstrated.
Darrow and Stotts (1954), Camp ££;£l. (1955), and Huston 2£_gl. (1956)
found significant decreases in feather picking and, consequently, sig-
nificant improvement in market grade when broilers were debeaked.

When feather picking was not a problem, differences in feather score
and market grade were not observed (Lonsdale ££;31., 1957; Vondell and
and Ringrose 1957; Keene gE_31., 1959b; and Krueger 2£_El°' 1961).

Debeaking one—half or less of the beak has no deleterious effect
on growth rate (Darrow and Stotts, 1954; Camp ££_al., 1955; Huston E£_El"
1956; Lonsdale ££_gl., 1957; Vondell and Ringrose, 1957; and Keene gt_al.,
1959a). Camp ££_al. (1955) found that debeaking 1/3 to 1/2 of both man-
dilbes actually improved the growth rate of males but had no effect on
females. Debeaking 2/3 of the beak, in most experiments, caused a
significant decrease in growth rate up to at least 10 weeks of age (Camp
££_31., 1955; Lonsdale ££_al., 1957; Vondell and Ringrose, 1957). How-
ever, Huston g£_£l., (1956) found no effect from debeaking 2/3 of the
upper mandible.

Few studies have been made comparing the effects that the various
methods of debeaking may have on broiler performance. Searing the beaks
of day-old chicks prevented beak regrowth better than did block debeak-
ing (Davis £E_El' 1957). Comparisons between research using block de-

beaking and research in which only the upper mandible is removed show

very similar results. That is, birds debeaked 1/2 did well regardless
of the method used and birds debeaked 2/3 did poorly (Darrow and Stotts,
1954; Camp e£_al., 1955; Huston EE_§l" 1956; Lonsdale ££_gl., 1957;
Vondell and Ringrose, 1957; Keene £5.21” 1959b; Krueger 2£_gl., 1961).

Feed efficiency has usually been found to be slightly, but not
significantly, improved by debeaking (Darrow and Stotts, 1954; Camp
.EE_El°’ 1955; Huston.Et_al., 1956; Lonsdale 2£_al., 1957; Vondell and
Ringrose, 1957; and Keene et al., 1959b).

Broilers debeaked at one day of age did not perform significantly
different from broilers debeaked at two weeks (Krueger 3£_al., 1961),
three weeks (Darrow and Stotts, 1954), or five weeks of age (Camp 2£_al.,
1955. However, Davis 2£_al., (1957) found that birds debeaked at 10
days of age were physically less capable of picking at 10 weeks of age
than were birds debeaked at one day of age.

Huston §£_al., (1956) found that mandibles debeaked 1/3 at one day
of age grew back to the same length as the controls by 10 weeks of age.
Beaks debeaked 1/2 were still shorter than the controls at 10 weeks of

age and were not significantly different from beaks debeaked 2/3.

Debeaking Pullets

 

Effects on birds during the_growing period -- The effects of de-

 

beaking Leghorn-type chickens are very similar to those observed in
broilers. Debeaking 1/2 of the upper mandible at one day of age had no
effect on growth to five months of age (Morgan, 1957). Debeaking 2/3 or
more of the upper or both mandibles at ages ranging from one day to 12
weeks significantly restricted growth rate (McDonald, 1956; Bramhall,

1962; Slinger et 81., 1962s-Bramhall, 1963; Slinger and Pepper, 1964).

Despite the favorable results observed from debeaking 1/2 or less,
temporary growth depression has been found (McDonald, 1956; Keene ££_31.,
1959a). Debeaking 1/2 caused a temporary drop in adrenal ascorbic acid
in bursectomized birds (Perek and Bedrak, 1962). The addition of aureo-
mycin to the diet hastened the return to normal adrenal ascorbic acid
values.

An interesting observation reported in the literature was that birds
debeaked 2/3 at 8 to 10 weeks of age consumed very little grit (Slinger
2£_al., 1962; McIntosh ££_al., 1962). Feed consumption was significantly
reduced in birds debeaked 1/2 at one day of age (McDonald, 1956). Appar-
ently, impairment of the ability to eat was not involved since the de—
beaked birds consumed enough feed to maintain normal growth and spent the
same amount of time at the feed trough as did the controls.

Effects on adult birds -— Debeaking 1/2 of the upper or both mandi-

 

bles during the growing period had no adverse effects on egg production,
mortality or egg weight when the birds were in floor pens (Morgan, 1957;
Noles 2£_al., 1962). Mortality was significantly reduced by block de-
beaking 1/2 in one experiment, but in a succeeding experiment by the
same researchers significant differences in mortality could not be dem-
onstrated (Noles ££_al., 1962). Debeaking 1/2 of the upper mandible
twice (at one day of age and again just before sexual maturity) had no
effect on egg production or mortality (Morgan, 1957).

Debeaking 1/2 of the upper mandible and 4 mm. of the lower man-
dible after the onset of laying had no adverse effect on egg production,
except when done in January (Bray ££_al., 1960). Debeaking at that time
produced approximately a 20 percent drop in egg production in White Rocks

and Rhode Island Reds but had no effect on the egg production of White

Leghorns. Egg production in all three breeds for the 40-week test
period was not significantly affected, but significant body weight
losses were found.

Debeaking 2/3 of the upper mandible and 1/3 of the lower mandible
at 8 weeks of age significantly retarded age of sexual maturity and de-
creased feed consumption but had no effect on egg production for the
first 20 weeks of lay (Slinger and Pepper, 1964). In the same exper-
iment, debeaking at 20 weeks of age did not retard age of sexual matu-
rity and feed consumption was decreased only during the first 4 weeks
after debeaking. The birds debeaked at 8 weeks of age weighed signif—
icantly less than the controls through 20 weeks of lay, but birds de-
beaked at 20 weeks of age showed no significant differences in body
weight at any time of measurement.

Bauermann (1959) measured feed wastage and found that prior to de-
beaking, his birds wasted 5 to 25 percent of the feed. After debeaking,
only 0.5 to 2.0 percent of the feed was wasted. Non-debeaked controls
were not used for comparison, however. In a later trial with controls,
the non-debeaked birds wasted five times as much feed as did the debeaked
birds. Noles EE_2$°' (1962) found that feed efficiency was highly signif-
icantly improved by debeaking 1/2 of both mandibles. However, in a pre-
ceding experiment, the controls had highly significantly better feed
conversion. A.Texas commercial producer (Sink, 1964) reported that
severe debeaking reduced feed consumption “too far". iAfter debeaking
rsithin l/B-inch of the nostril, feed consumption did not increase beyond

18 pounds per 100 birds per day by 52 weeks of age.

‘Qage population size

The severity of debeaking is usually increased as the number of birds

per cage is increased and as problems with cannibalism increase. It
would appear, therefore, that an adequate study of debeaking should
take into consideration possible interactions between level of debeak-
ing and cage population size.

Presently available research evidence which compares the perform-
ance of different cage p0pulation sizes is fairly inconclusive. Re-
search which has been statistically analyzed is very sparse, but a
number of non-statistical reports have been published. Research lit-
erature cited herein on cage population size was 39! statistically
analyzed unless so stated. The general trend of these reports indicate
that, as a rule, a decline in egg production and an increase in mortal-
ity occurs as the number of birds per cage is increased.

The difference in egg production between birds in l-bird and 2-bird
cages has usually been reported as negligible (McCluskey, 1962; Anon.,
1963b; Johnson and Zindel, 1963; Michelson, 1963; Ostrander, 1963;

Bezpa, 1964; Lowe and Heywang, 1964; Quisenberry g£_gl.. 1964; Wilson

and Harms, 1964). Lowe and Heywang (1964) statistically analyzed egg
production data fro-.1-bird and 24bird cages and found no statistically
significant differences. The differences in egg production between birds
in l-bird and 2-bird cages versus 36bird cages is a little more clear-cut,
but again, statistical differences have not been reported. In most exper-
iments reported, birds in 3-bird cages laid fewer eggs than birds in 1 or
24bird cages (McCluskey, 1962; Anon.. 1963a; Anon., 1963b; Bell, 1963;
Michalson, 1963; Quisenberry £31., 1964; Wilson and Harms, 1964). Con-
parisons between labird and Sabird cages have also indicated that birds

in l-bird cages lay better (Ostrander, 1963; Lowe and Heywang, 1964;

Quisenberry et al., 1964). On the other hand Quisenberry et al., (1964)

found that birds in 5-bird cages laid better than did birds in 3-bird
cages. Lowe and Heywang (1964) found a significant difference in egg
production between birds in l-bird and S—bird cages when calculated
on a hen-housed basis but not when calculated on a hen-day basis.

The egg production of birds housed in units of 7 to 25 birds per
cage has also been reported as being lower than that of birds in 1-bird
cages (Shupe and Quisenberry, 1961; Michalson, 1963; Ostrander, 1963;
Quisenberry ££_al., 1964). Shupe and Quisenberry (1961) found that egg
production of birds in l-bird cages was significantly higher than the
production of birds in 25-bird cages. Carlson and Strangeland (1960),
however, found no consistent differences between the production of birds
in l-bird cages and birds in lB-bird cages.

Statistical analyses of differences in mortality have not, to our
knowledge, been reported in the literature. Very little numerical dif-
ference in mortality between l-bird and 2-bird cages has been reported
(McCluskey, 1962; Anon., 1963b; Michelson, 1963; Lowe and Heywang, 1964;
Quisenberry ££_§l., 1964;'Wilson and Harms, 1964). In comparisons of
l-bird and 2-bird cages with S-bird cages, the results reported in three
experiments showed differences of less than two percent (Anon., 1963a;
Anon., 1963b; Michelson, 1963); one experimenter simply reported "greater
mortality" in 3-bird cages (McCluskey, 1962); and three reports showed a
4 to 7 percent higher mortality in 3-bird cages (Bell, 1963; Quisenberry
.2£_2l" 1964;'Wilson and Harms, 1964). Research comparing l-bird cages
with 5-bird, 10-bird or 25-bird cages showed 8 to 35 percent less mortal-
ity in the l-bird cages (Shupe and Quisenberry, 1961; Ostrander, 1963;
Lowe and Heywang, 1964). A six-month progress report by Quisenberry

et al., (1964), however, showed only 1.1 percent mortality in 10-bird

cages as compared with 0.0 percent mortality in l—bird cages. Although
the overall mortality picture may be somewhat clouded, when vent pick-
ing occurs this form of mortality can be directly correlated with the
number of birds per cage (Bell, 1963; Lowe and Heywang, 1964).

Comparisons of body weights of birds in l-, 2-, 3-, 5-, 7-, 10-,
and 25-bird cages have not revealed any clear-cut differences (Shupe and
Quisenberry, 1961; Lowe and Heywang, 1964; Quisenberry g£_gl., 1964).

Michelson (1963) and Lowe and Heywang (1964) found practically no
differences in feed conversion between 1, 2, 3, 5, and 20 birds per
cage. Shupe and Quisenberry (1961), however, reported that birds
housed in single cages had significantly better feed conversion than did
birds in 25-bird cages.

Comparisons of egg weights from birds in l-, 2-, 3-, 5-, 7-, 10-,
and 25-bird cages have not revealed any consistent differences (Shupe

and Quisenberry, 1961; Quisenberry et al., 1964).

OBJECTIVES

The objectives of this project were:

1. To determine the effect of severe debeaking on egg production,
feed consumption, mortality, body weight, egg weight and beak
regrowth of caged laying hens.

2. To determine the presence or absence of interaction between
the degree of debeaking and cage population size.

3. To determine the effect of cage population size on egg pro-
duction, feed consumption, mortality, body weight and egg

weight of caged laying hens.

EXPERIMENTAL PROCEDURE

Pullets from a closed population of pure line Single Comb'White
Leghorns (Michigan State University) were debeaked at 18 weeks of age
and randomly placed in l-bird 8" x 16" cages and 3—bird 12" x 18" cages.
Other pullets from the same strain were debeaked at 24 weeks of age and
placed in 2l-bird 3' x 4' cages. None of the birds had been previously
debeaked. Another group of pullets which had been debeaked 1/2 one to
five weeks prior to the initiation of this experiment were debeaked again
at 25 weeks of age and placed in 2-bird 8" x 16" cages. The "controls"
in this case were not debeaked a second time. The number of birds used
for each group is presented in Table 1.

Three degrees of debeaking plus a non-debeaked control were used.
The three degrees were 1/2, 3/4, and all of the distance between the tip
of the beak and the nostrils. The group in which all of the beak in
front of the nostrils was removed will be hereinafter referred to as
"entire" or "E". Both upper and lower mandibles were removed with one
stroke of the electric debeaker, with the throat held back in such a
manner as to leave the lower mandible slightly longer than the upper
mandible. This method is referred to in the literature as ”block
debeaking". Photographs of the resultant gradations are presented in
Figures 1 through 13.

Understandably, the conditions of the experiment do not permit
completely comparable management conditions between the different cage
sizes. These conditions are presented in Table 2 so that they may be

taken into consideration. A lighting period of 13.5 hours per day was

10

 

 

11

used throughout the experiment. .An all-mash feed containing 15 percent
protein, 756 calories per pound of productive energy, 2.8 percent cal-
cium and 0.9 percent phosphorus was used. The ration fed is presented
in Table 3.

The characteristics measured were egg production, feed consumption,
egg weight, body weight, beak length and mortality. Feed consumption
was measured weekly from four replicates of each treatment in the l-bird
and 3-bird cages and from each of the four treatments in 2l-bird cages
through the first 20 weeks of lay. From the twentieth week of lay until
the end of the experiment, feed consumption was measured in 28-day pe-
riods. All eggs were collected for five continuous days at the end of
each 28-day period and weighed to the nearest gram. Eggs were stored
from two to five days at 60° F. before weighing. All eggs collected on
any one date were stored for the same length of time. Body weights and
beak length were measured at the end of each 28-day period, beginning
6 weeks after debeaking. The 28-day periods were based both on age of
birds and weeks after debeaking in order to compare measurements be-
tween the different cage sizes. All measurements were continued until
the birds were 500 days of age.

All birds that died before 25 weeks of age were removed from com-
putation. In addition, one bird that exhibited male characteristics
and failed to lay any eggs during the experiment was removed from the
computation of egg production, body weight and beak length. This bird
still consumed feed, however, so it could not be removed from the com—
putation of feed consumption. There was no predominance of any treat-
ment group among the birds thus removed.

Statistical analyses were based on several forms of analysis of

12

variance (Guenther, 1964). In analyzing egg production, feed consump—
tion and feed efficiency, averages for each treatment were used as a
single observation and the pooled variance (82) of all individual ob-
servation was used as error mean square in a two-way analysis of
variancel. Days to first egg, changes in beak length, and changes in
body weight were analyzed by the one-way analysis of variance.

Egg weight, body weight, and beak length would normally be ex-
pected to be affected by the age of the bird, so a three-way analysis
of variance in which time was used as the third variable was used to
analyze these factors. All significant differences demonstrated by
analysis of variance were further tested by use of Tukey's method for

multiple comparisons (Guenther, 1964).

 

1Dr. Stapleton, Statistics Department,‘Michigan State University.

RESULTS AND DISCUSSION

The two birds per cage group did not have a comparable non-debeaked
control and consequently, the data for this group are reported sepa-
rately from the data for the other groups.

A. gggrrroduction: Egg production figures are presented in Tables

 

4, S, and 6 and Graphs l and 2. An analysis of variance showed that
significant interactions between degree of debeaking and cage papula-
tion size did not occur, and therefore, all data except that for the
2-bird cages were combined. Consistent differences in egg production
between treatments during the first 20 weeks of lay were noticeable
(Graph 1), but significant differences were found only in comparisons
between entirely debeaked birds and the other three treatments. These
differences were all highly significant (P<:0.01). While the differ-
ences appeared to be smaller through the rest of the experiment (Graph
1), the differences between the entirely debeaked birds and the other
treatments were highly significant (P<10.01) over the entire experi-
mental period.from.25 weeks of age to 500 days of age. The results
observed for the birds in 24bird cages followed the same trend, but
the only significant difference (P<:0.05) found in this group was be-
tween the "controls" (debeaked prior to this experiment) and entirely
debeaked birds. The lack of significance in comparisons of egg pro-
duction between the controls, 1/2 and 3/4 debeaked birds in all cage
sizes in this experiment are in agreement with the findings previously
reported in the literature (Morgan, 1957; Bray e_t_gl., 1960; Roles g;
51., 1962; Slinger and Pepper, 1964).

A significant difference (P<10.05) in egg production was found

13

14

between birds in l-bird cages and birds in 3-bird cages during the first
20 weeks of lay. The differences between birds in 3—bird cages and
birds in the other two cage sizes were not significant. The differences
in egg production were increased with.time, however, and the difference
between egg production in l-bird cages and Zl-bird cages was highly
significant (P<(0.0l) for the entire experflmental period. Egg produc-
tion over this period was also significantly different (P<:0.05) be-
tween l-bird and 3-bird cages. The highly significant difference in
egg production observed between birds in lébird cages and birds in 21-
bird cages is in accord with the results previously reported by Shupe

and Quisenberry (1961).

3. Days to First Egg; The number of days from hatching to the first
egg laid in a regular production cycle are presented in Table 7. un-
fortunately, initial egg records are available only for the birds in
l-bird cages. Consequently, comparisons between cage pOpulation size
and age at sexual maturity could not be made. The birds debeaked 3/4
took slightly longer (13 days) than the controls in coming into pro-
duction, but this difference was not significant. The birds that were
entirely debeaked, however, were highly significantly longer (P<:0.01)
in coming into lay than birds in any of the other three treatments.
Slinger and Pepper (1964) found that sexual maturity was significantly
delayed when birds were debeaked 2/3 at 8 weeks of age, but no signif-
icant difference was observed when birds were debeaked 2/3 at 20 weeks
of age.

C. Feed Consumption: The pertinent data on feed consumption are re-

ported in Tables 8 and 9 and Graphs 3, 4 and 5. No significant

15

interaction was found, so the various treatments were combined for
analysis. For the first 20 weeks of lay feed consumption differences
were all highly significant (P4<O.Ol). Feed consumption decreased as
degree of debeaking increased in severity and feed consumption de-
creased as cage population size increased. Feed consumption over the
entire experiment, however, was more variable, although the same trend
was still evident. Differences in feed consumption between the con—
trols and birds debeaked 3/u or entire were still highly significant
(P¢(0.0l) for the test period, but birds debeaked 1/2 were not signif-
icantly different from the controls or birds debeaked 3/fl. Differences
in feed consumption were significant (P<:0.05) between entirely de-
beaked birds and birds debeaked 3/h, and highly significant (P<:0.01)
between entirely debeaked birds and birds debeaked 1/2. These results
are somewhat at variance with results reported in the literature.
Slinger and Pepper (196a) found no significant differences in feed con-
sumption between controls and birds debeaked 2/3 over the first 20
weeks of lay when the birds were debeaked at 20 weeks of age. However,
feed consumption differences were significant when the birds were de-
beaked at 8 weeks of age.

The differences in feed consumption for the entire experiment be-
tween the different cage population size groups were highly significant

(P<0.01).

D. Feed Efficiency: Feed efficiency figures are presented in Tables
10 and 11. Analysis of variance revealed that a highly significant
(P<:0.0l) interaction in feed efficiency occurred between degree of

debeaking and cage population size. Consequently, each treatment was

16

treated separately. With 66 possible combinations of comparisons,
complete understanding of the results is difficult. In the first 20
weeks of egg production, most differences were highly significant
(P<:0.0l). The birds subjected to entire debeaking required highly
significantly (P<:0.0l) more feed to produce a dozen eggs than birds
in any of the other treatments. Eleven of the 17 non-significant
differences observed were between 1/2 and 3/# debeaked groups.

Overall feed efficiency to 500 days of age, however, shows few
significant differences. Three treatments (l-bird entire, Zlébird
entire, and Zl-bird 3/u) accounted for all highly significant (P<:0.0l)
differences. Twenty-one-bird 3/h was highly significantly different
(P<C0.0l) from.all other treatments except l-bird 1/2, Zl-bird 1/2,
and 3-bird 3/h. Twenty-one-bird 3/h was significantly (P<:0.05) dif-
ferent from l-bird l/Z and Zl-bird 1/2. One-bird I and 2l6bird B‘were
highly significantly different (P<:0.0l) from.all but one (3Abird 1/2)
of the 1/2 and 3/h treatments. Twenty-one-bird entire was signifi-
cantly different (P<.0.0S) from.3-bird 1/2. The 3-bird control treat-
ment was significantly different (2:30.05) from.21-bird 3/h and 3-bird
3/h. All other differences in feed efficiency to 500 days of age were
non-significant. These data must be viewed in the light of the findings
of Noles g£_§l., (1962) that a highly significant difference in feed

efficiency can be completely reversed in a subsequent experiment.

3. Feed wastage; Feed wastage was measured for one week among one-
fourth of the birds in 3Abird batteries. The results are reported in
Table 12. Attempts at measuring feed wastage were discontinued because

of problems in feeding and egg collection. The reliability of these data

17

is unknown, since statistical analysis was not possible. The magni-
tude of the differences reported here is much less than that reported

by Bauermann (1959).

F. Body weight: The pertinent data on body weight are presented in
Tables 13, 14 and 15 and Graphs 6, 7, 8 and 9. The well-known effect
of age on body weight prevented direct comparisons between body weights
of birds in all treatments, since debeaking and housing was performed
at different dates for the different cage groups. However, the birds
in the l-bird and 3-bird cages were debeaked and housed at the same
age, so valid comparisons could be made between the two. The differ-
ence in body weight gains between birds in l-bird and 3-bird cages

was highly significant (P<f0.01) for the first 6 weeks after debeaking.
During the following 8 weeks, however, no significant differences in
body weight were observed. The not change in body weight over the
entire SOdweek period was not significantly different between the birds
in l-bird and 3-bird cages.

In comparing debeaking treatments in labird and 3-bird cages, the
body weight gains of the controls, 1/2 and 3/h treatments were highly
significantly greater (P<:O.91) than that of the birds in the entirely
debeaked treatments during the first 6 weeks following debeaking. The
controls made significantly higher gains than the birds debeaked 1/2
(P< 0.05) and SI“ (P< 0.01). Significant differences in body weight
gain during the first 6 weeks after debeaking were not found between
birds debeaked 1/2 and 3/h. Body weight gains over the following 8
weeks were not found to be significantly different between any of the

debeaking treatments. The net change in body weight over the entire

18

50-week period was significantly different between treatments at the
same significance levels as at 6 weeks after debeaking.

In the 2-bird cages the same results were found -- the "controls"
weighed highly significantly more (P<'0.01) than the birds in the other
treatments, and the entirely-debeaked birds weighed highly significantly
less (P<f0.01). The birds debeaked 1/2 and 3/% were not significantly
different from each other in body weight.

The relationship of body weight to severity of debeaking in 21-bird
cages, however, was quite different from the relationship found in the
other cage sizes. In 21-bird cages the birds debeaked 1/2 and S/h
attained the highest average body weights. The differences between
these two treatments and the controls and entirely debeaked birds were
highly significant (P<10.0l}. The average body weights of the birds de-
beaked 1/2 and 3/& were not significantly different from each other.

The controls weighed significantly (P<(0.05) more than the entirely de-
beaked birds. It is possible that the lower body weight of the controls
reflected a greater incidence of feather picking among this group. How-
ever, this would not explain why the debeaked birds in 21-bird cages
would gain more than debeaked birds in other cage population sizes.

Previous research, although sparse, supports the present findings.
Studies of birds in floor pens (Bray and Ridlen, 1960; Slinger and
Pepper, 1964) showed that debeaking l/2 significantly reduced body weight.
Comparisons of body weights between cage population sizes have not re-
vealed any significant differences (Shupe and Quisenberry, 1961; Lowe
and Heywang, 1964; Quisenberry g£_gl., 1964).

G. Beak Length: Beak length data are reported in Tables 16 and 17 and

 

graph 10. Photographs of beaks at different ages are presented in

19

Figures 1 through 13. Initial beak length was measured only on birds
in l-bird cages, so analysis is restricted primarily to this group.
Beak length was measured to the nearest millimeter with calipers. An
increase in beak length appeared to occur in all debeaked treatments
until lh-18 weeks after debeaking (Graph 10). Statistical analysis,
however, did not reveal any significant differences between the beak
growth of the controls. 1/2 and 3/4 debeaked birds for the first 18
weeks following debeaking. The difference in beak growth rate be-
tween controls and entirely debeaked birds for this period. however,
was highly significant (P<<0.0l). Eighteen weeks after debeaking, the
length of the beaks of the entirely debeaked birds was no longer sig-
nificantly different from that of the birds debeaked 3/4. Visual
observations, however, showed the presence of the usual horny covering
on the beaks of birds debeaked 3/h, while the beaks of the entirely de-
beaked treatment had a leathery covering (see Figures 1 - 13). Changes
in beak length in the debeaked treatments from 18 weeks after debeaking
to the end of the experiment were not significantly different from.the
controls.

It is interesting to note that the beaks of the Z-birds per cage
"controls" grew back to where they were not significantly different
from.the beak lengths of non-debeaked controls in the other treatments.
This would tend to indicate that complete beak regrowth occurs when less
than 1/2 of the beak is removed. However, records were not available
on the exact level of debeaking initially performed on the "controls”
in 2-bird cages.

The degree of beak regrowth was comparable in most of the cage

population size groups. Some differences were noted, however. Highly

20

significant differences (P<:0.01) occurred between the birds debeaked
1/2 in l-bird, 3-bird and Zl-bird cages. The entirely debeaked birds
in 21-bird cages finished the experiment with highly significantly
shorter (P<(0.0l) beaks than birds in the other entirely debeaked
treatments. The possibility exists that these differences existed

at the tfime of debeaking. The magnitude of difference between the
different levels of debeaking, however, is such that these differences

would not appear to seriously affect interpretations of results.

H. Egg weight: Average egg weights for the experflment are reported
in Table 18. Differences in egg weights between debeaking treatments
were not significant. Differences in egg weight between l-bird,~3-
bird and Zl-bird cages were not significant. Egg weights from.Z-bird
cages were significantly higher (P<(0.0S) than some, but not all, of

the other treatments.

I. ‘Mortalitz: ‘Mortality data are reported in Tables 19 and 20. A
total of ten blow-outs and pick-outs occurred.smong the 98 deaths.
Four of these occurred in 24bird cages, five occurred in 34bird cages.
and one occurred in the 21—bird cages. Three blowbouts occurred in
controls, five in birds debeaked 1/2, one in a bird debeaked 3/h, and

one in an entirely debeaked bird.

SUMMARY AND CONCLUSIONS

The results of this experiment clearly demonstrate that there is
a practical limit to the severity of debeaking that should be used in
commercial caged layer Operations. Block debeaking just in front of
the nostrils caused highly significant changes in production character-
istics: age to sexual maturity was prolonged, egg production was de-
creased, feed consumption was decreased, feed efficiency was poorer,
and body weight gains were smaller.

Intermediate degrees of debeaking did not cause any significant
loss in egg production. Debeaking 3/u produced a significant drop
in feed consumption, and the drOp in feed consumption from.debeaking
1/2 approached significance. .A corollary improvement in feed effi-
ciency, however, was obscured by interactions with cage population
size. Debeaking both 1/2 and 3/4 produced significantly smaller body
weight gains than in the controls.

The results of this experiment tend to indicate that debeaking
1/2 to 3/# at 18 weeks of age is a normally safe practice without
adverse effects on egg production. Indeed, the savings in feed con-
sumption may make it desirable to debeak even where cannibalism is
not a problem. However, it is possible that the lowered feed con-
sumption might mean that debeaked birds would be more susceptible to
stresses that increase the feed requirement. The present data indicate
that debeaking beyond 3/h should be avoided.

The reasons why changes in production characteristics result from

debeaking have not been established. It is popularly assumed that de-

21

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7 .
< .
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22

beaking reduces the ability to waste feed, thus reducing feed consump-
tion. However, a reduction in feed wastage would be expected to result
in an improvement in feed efficiency. This did not occur in the en-
tirely debeaked birds used in this experiment. A brief attempt at
measuring feed wastage during this experiment failed to show any great
differences in relative feed wastage. The sharp drop in feed consump—
tion below physiological needs immediately after debeaking would tend
to indicate a loss of desire or ability to eat rather than a loss of
ability to waste feed. The beak is plentifully supplied with nerves,
so it should not seem overly speculative to postulate that severing
the beak would affect the sensitivity of the beak. It is interesting
to note that many birds reacted to the placing of the calipers on the
beak when taking beak.measurements. Ewen controls often reacted to
the placing of the caliper point at or near the nostril. .A response
could always be elicited by scraping a fingernail ever the beak.

If debeaking made the beak over-sensitive, the birds would have
an incentive to eat less feed. The reduction in feed consumption alone
could be used to explain most of the other results obtained. The mod-
erate reduction in feed consumption in birds debeaked 1/2 and 3/h was
not severe enough to affect egg production but was reflected in lower
body weight gains. The feed consumption in entirely debeaked birds,
however, was reduced below physiological needs for normal egg produc-
tion.

Other reasons for the results obtained are certainly possible.
Further research.must be conducted before a physiological basis for
the results observed in this experiment can be established.

The data on beak regrowth help clarify one of the reasons commonly

23

given for the use of severe levels of debeaking. It is claimed that
beaks of lightly debeaked birds grow back to their former size. In
this experiment, however, regrowth was limited. What actually happened
was that the beaks tended to resume their former shape even though they
were not quite as long. The results free the 2-bird "controls" indi-
cated that complete regrowth can occur when lighter debeaking is
practiced.

Statistical interaction between levels of debeaking and cage popu-
lation size was found only in measurements of feed efficiency, beak
length, body weight and egg weight. If more cannibalism had occurred,
more interaction would probably have occurred.

Significant differences in egg production and feed consumption
were found between the different cage population sizes. The birds in
l-bird cages laid significantly better and ate significantly more feed
than birds in 3-bird and 21-bird cages. Social interaction between
birds probably caused some of the difference, but how much is unknown.
Recommendations for optimmn cage population size cannot be based en-
tirely on these results since economic factors must also be taken into

consideration.

24

Table 1. Experimental design. Upper figure is number of cages;
lower figure is number of birds

 

L
fi

___<:ontrol .112. 3.42. 92.122
1-bird 2h/24 24/2u 24/24 24/2h
2-bird 18/36 18/36 18/36 18/36
36bird 12/36 12/36 12/36 12/36

Zldbird 1/21 1/21 1/21 1/21

 

Table 2. Functional housing conditions

 

Feeder waterer Floor
space space space Cubic
lin. in./bird lin. in./bird sq. ft./bird ft./bird

 

25

Table 3. (Souposition of diet

W

 

Ingredients Percent
Ground yellow corn 3h.5
Ground oats 20.0
Wheat bran 15.0
Flour middlings 10.0
Alfalfa meal (17% dehyd.) 3.0
Dried skim milk 2.0
White fish.mea1 2.5
Heat scraps 3.0
Soybean oil meal (hh%.prot.) 2.5
Ground oyster shell flour 5.0
Steamed bone meal 1.5
Salt 0.6
lish oil (NOD, 2000A) 0A

 

Total 100.0

26

Table 0. Egg production -- 20 weeks of lay (25 to uh'weeks of age)

A. Average total production:

i4!”- L/l _3_/_l_g E g Average
l—b ird 88 87 71 38 71
3—b ird 79 71 7 1 1+4 66
21-b ird Z_l_ fl _6_3_ 52 69
Average 79 75 68 u1
Debeaking L.S.D. .05 a 12.7 Cages L.S.D. .05 a
.01 3 17.3 .01 3 13.6
B. Percent production (hen-housed)
_c- 1.42. .312 _n_.
l-bird 63.1 62.3 50.5 29.5
3-bird 56.6 50.6 51.0 31.2
21-bird 50.3 118.0 115.2 28.6
C. Percent product ion (hen-day)
.9. 1a 229. .22..
l-bird 63.1 62.3 52.0 30.5
3—bird 58.3 52.2 52.0 32.1
21-bird 50.3 119.5 45.6 28.6

 

Q G 8 control

a E ' entire

Table 5. Total egg production (25 weeks to 500 days of age)

27

 

 

A. Average total production:

La

l-bird
3-bird
Zl-bird

Average

Debeaking L.S.D.

218
17“
171

188

lgg'
213
169
‘ggg

179

.05 = 27.7
.01 3 37.3

B. Percent production (hen-housed)

1-bird

3-bird

21-bird

_£L.
67.0
53.5

52.6

1.4.2.

65.6
51.9

48.1

C. Percent production (hen-day)

l-bird
34bird

21-b1rd

.9.
67.6
57.7

53.8

141

66.4

56.3

50.h‘

345
181
172
‘12;

173

Cages L.S.D.

2.41

55.7
52.8

50.7

9/11

”.7
57.#

53.5

_§L/Z. Average
135 187
137 163
IQQ, 150
127
.05 8 21.4
.01 = 29.“
._§_
#5.3
“2.1
33.3
.11.
#7.“
46.0
33.9

 

A C 8 control

[2,3 I entire

28

Table 6. Egg production, 2-bird cages (25 weeks to 500 days of age)

 

 

c A 1/2 3/4 n 42.
Total average production 132 126 112 88
Percent production/ 28.3 24.7 20.2 16.6
hen-housed
Percent production/ #6.2 42.6 39.0 31.6
hen-day

 

‘11 C 8 debeaked control

‘3': 8 entire

Table 7. Days to first egg (l-bird cages)

 

 

Control 178 L.S.D. .05 8 27.8
.01 3 35.7

1/2 178

3/h 191

Entire 23h

 

 

 

 

 

 

 

29

Table 8. Feed consumption (lbe./bird/day) 25 to 44 weeks of age

 

 

_g_L1. L/_2_ 313 La Average
l-bird .329 .289 .248 .244 .278
36bird .299 .269 .251 .223 .261
21-b ird ._2_8_2 :_2_§_Q a_2__2_§_ ;_2_(_)_7_ .2339.
Average .306 .273 .242 .225
Debeaking L.S.D. .05 I .014 Cages L.S.D. .05 8 .011
.01 8 .017 .01 8 .014

 

Table 9. Feed consumption (lbs./bird/day) 25 weeks to 500 days of age

 

 

ill _1_/_2_ 315 i& Average
1-bird . 329 . 307 . 283 .259 . 293
3-bird .302 .279 .259 .235 .269
21-bird :15; ._2_§_4 fiL _._1_§_Z_ .223
Average .293 .273 .252 .227
Debeaking L.S.D. .05 I .023 Cages L.S.D. .05 = .019
.01 I! .028 .01 8 .023

 

A C i control

8. E 8 entire

31

Table 12. Feed wastage (3-bird cages, 44 weeks of age)

 

 

 

Total feed Wasted feed Percent
Treatment (lbs/bird/day) (lbs/bird/day) wasted
Cbntrol .357 .033 8.9
1/2 .270 .025 9.2
3/4 .254 .018 7.1

Entire .259 .019 7.3

 

32

 

 

 

Table 13. Body weight gains (lbs.)
42.4 __.1/2 112 L43

A. 0 - 6 weeks after debeaking:

l-bird 0.74 0.50 0.45 0.23

3-bird 0.91 0.82 0.69 0.47
B. 6 - 14 weeks after debeaking:

l-bird 0.27 0.32 0.32 0.19
C. 14 - 26 weeks after debeaking:

l-bird 0.50 0.65 0.63 0.75

3-bird 0.29 0.41 0.46 0.54
D. 0 - 50 weeks after debeaking:

l-bird 0.62 0.40 1.24 0.55

3-bird 1.47 1.17 1.11 0.85
A C 3 control
a B . entire

33

Table 14. Body weight averages (lbs.)

 

 

4.3.4 1.4 2.41 .22?—
A. At time of debeaking:
1-bird 3.0 3.0 2.9 2.9
3-bird 2.9 2.9 2.9 2.8
21-bird 3.6 3.5 3.6 3.5
B. At 25 weeks of age:
l-bird 3.7 3.5 3.3 3.1
3-bird 3.8 3.6 3.6 3.3
21-bird 3.6 . 3.6 3.6 3.5
C. .At 44 weeks of age:
l-bird 4.5 4.4 4.3 4.0
3-bird 4.3 4.3 4.3 4.1
21-bird 4.1 4.3 4.5 4.0
D. At 500 days of age:
labird 4.5 4.5 4.1 3.7
3-bird 4.3 4.2 4.0 3.7
21-bird 4.5 4.7 4.9 4.2

 

(1’0 8 control

[3,8 I entire

32

 

 

 

Table 13. Body weight gains (lbs.)
.24 ........1/2 9.4: 2.13

A. 0 - 6 weeks after debeaking:

l-bird 0.74 0.50 0.45 0.23

3-bird 0.91 0.82 0.69 0.47
B. 6 - 14 weeks after debeaking:

l-bird 0.27 0.32 0.32 0.19

3-bird 0.22 0.22 0.27 0.32
C. 14 - 26 weeks after debeaking:

l-bird 0.50 0.65 0.63 0.75

3-bird 0.29 0.41 0.46 0.54
D. 0 - 50 weeks after debeaking:

labird 0.62 0.40 1.24 0.55

3-bird 1.47 1.17 1.11 0.85
A C I control
[3.3 8 entire

33

Table 14. Body weight averages (lbs.)

 

 

4.2.4 1.42. 242 3.4
A. At time of debeaking:
l-bird 3.0 3.0 2.9 2.9
3-bird 2.9 2.9 2.9 2.8
21-bird 3.6 3.5 3.6 3.5
B. At 25 weeks of age:
l-bird 3.7 3.5 3.3 3.1
3-bird 3.8 3.6 3.6 3.3
21-bird 3.6 , 3.6 3.6 3.5
C. .At 44 weeks of age:
l-bird 4.5 4.4 4.3 4.0
3-bird 4.3 4.3 4.3 4.1
21-bird 4.1 4.3 4.5 4.0
D. At 500 days of age:
1-bird 4.5 4.5 4.1 3.7
3-bird 4.3 4.2 4.0 3.7
21-bird 4.5 4.7 4.9 4.2

 

A C 8 control

[Z_E a entire

Table 15. Body weight averages, 2-bird cages (lbs.)

34

 

 

At time of debeaking:
At 44 weeks of age:

At 500 days of age:

4.6

 

v...—

A C = debeaked control

& E = entire

1.42.

3.“

3.9

.311

3.5

3.9

4.5

U
a
U1

 

 

 

 

 

 

 

Table 16. Beak length (cm.) l-bird cages
Weeks after debeakiggf
Before 0 10 18 26 54 42 50
Control 1.8 1.8 1.8 1.9 1.8 1.9 2.0 1.8
1/2 1.8 0.7 0.9 1.1 1.1 1.0 1.1 1.0
3/4 1.8 0.4 0.6 0.6 0.6 0.6 0.7 0.5
Entire 1.8 0.0 0.4 0.5 0.5 0.5 0.5 0.5

 

Tabl

e 17. Beak length (cm.)

36

l-bird, 3-bird and 21-bird cages

 

 

 

.41. 1/2 3/4 E 12
A. 10 weeks after debeaking:
l-bird 1.8 0.9 0.6 0.4
S-bird 1.8 0.9 0.5 0.5
21-bird 1.8 1.2 0.5 0.3
B. 18 weeks after debeaking:
l-bird 1.9 1.1 0.6 0.5
3-bird 1.9 1.2 0.7 0.6
21-bird 1.8 1.4 0.7 0.4
C. 50 weeks after debeaking:
l-bird 1.8 1.0 0.5 0.5
S-bird 1.8 1.2 0.5 0.5
21-bird 1.9 1.5 0.6 0.3
£2_C = control
13 E = entire

37

Table 18. Average egg weight (gms) 25 weeks to 500 days of age

 

 

 

 

 

 

.211 1.42. 2.41 42.3-
l-b ird 54 53 55 56
24> ird 57 60 S9 56
3-b ird 54 55 S4 55
2 l-b ird 53 54 55 ‘ 54

 

A C = control

a E 8 entire

38

 

 

 

 

 

Table 19. Mortality (‘75) 25 weeks to 44 weeks of age

0 L1 1/2 3/4 E a
l-bird 0.0 4.4 8.3 13.6
Z-bitd 16.7 1101 8.3 16e7
3-bird 5.6 8.6 2.8 8.3
Table 20. Mortality (70 25 weeks to 500 days of age

0 a 1/2 3/4 a £2
2-bird 33.3 30.6 27.8 27.8
3-bird 13.9 25.0 25.0 27.8

 

A C 3 control

a E 8 entire

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43

Graph 5. Feed consumption - immediate effects of debeaking
in l-bird cages (initial consumption extrapolated
as average of first 3 weeks' consumption by controls)

 

 

 

 

«I! ‘0
0.20 ‘“ . .
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gigure 1. Cbntrol Figure 2. Debeeked 1/2

 

 

 

 

 

Figure 3. Debeeked 3/h Figure h. Entirely debeaked

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12.

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14.

LITERATURE CITED

Anon. 1963a. Crowding cage layers pays off. Poultry Digest
22(251):25. January.

Anon. 1963b. Three-bird cages best. Poultry Digest
22(241):26-27. January.

Bauermann, Julius F.. 1959. An investigation of the effect of
debeaking on feed wastage and fertility of Single Comb
White Leghorn chickens. Poultry Sci. 38:1189.

Bell, Donald, 1963. Two or three hens per cage? Poultry
Tribune 69(3):50-62. March.

Bezpa, John, 1964. How many birds to a cage? Poultry Digest
23(263):26-27. March.

Bramhall, E. L., 1962. Six-day-old debeaking. Poultry Tribune
68(8):14,28. October.

Bramhall, E. L., 1963. Early precision debeaking. Poultry
Tribune 69(9):17,45. September.

Bray, D. J., S. F. Ridlen and J. A. Gesell, 1960. Performance
of pullets debeaked at various times during the laying
year. Poultry Sci. 39:1546-1550.

Camp, A. A., J. H. Cartrite, J. H. Quisenberry and J. R. Couch,
1955. Debeaking in commercial broiler production. Poultry
Sci. 34: 371-3750

Carlson, C. W. and V. A. Strangeland, 1960. Protein levels and
furazolidone treatments versus cages and floor pens as
affecting egg production. Poultry Sci. 39:1239.

Darrow, M. I. and C. E. Stotts, 1954. The influence of debeaking
broilers upon growth rate, feed utilization and market
quality. Poultry Sci. 33:378-381.

Davis, Durrell, 1962. Reduce losses with proper debeaking.
Poultry Tribune 68(10):17,38. October.

Davis, B. H., J. L. Heath and P. S. WOodward, 1957. A comparison
of methods of debeaking broilers. Association of Southern
Agricultural Workers Proc. 54:241-242.

Godfrey, George F.. 1960. Why, when and how to debeak. Poultry
Tribune 66(7):15. August.

52

THI

wn-I‘

-‘\

‘ 1

15.

16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

27.

Guenther, William C., 1964. Analysis of Variance. Prentice-Hall,
Inc. Inglewood Cliffs, N. J. pp. 31-57, 99-129.

 

Huston, T. M., H. L. Fuller and C. K. Laurent, 1956. A compar-
ison of various methods of debeaking broilers. Poultry Sci.
35:806-810.

Johnson, H. S. and H. C. Zindel, 1963. Comparisons between
pullets housed in cages, on a slatted floor, and on a litter
floor. Report 11, 1960-61. Mich. Agr. Expt. Sta. Quart.
Bul. 45(4):664-678.

Keene, J. B., B. A. Tower and A. B. Watts, 1959a. A determination
of the immediate effects of debeaking day-old broiler-type
chickens. Poultry Sci. 38:738.

Keene, J. B., B. A. Tower and A. B. Watts, 1959b. The evaluation
debeaking broiler strain chicks at one and ten days of age
by two different methods. Association of Southern Agri-
cultural Workers Proc. 56:232.

Krueger, W. F., J. J.‘Woods, C. B. Ryan, J. C. Williams, R.‘W.
Lewis and J. H. Quisenberry, 1961. Effect of early vaccina-
tion for fowl pox on the performance of broilers. Texas
Agr. Expt. Sta. Misc. Publ. 479

Lonsdale, M. B., R. M. Vondell and R. C. Ringrose, 1957. De-
beaking at one day of age and the feeding of pellets to
broiler chickens. Poultry Sci. 36:565-571.

Lowe, R. W. and B. W. Heywang, 1964. Performance of single and
multiple caged White Leghorn layers. Poultry Sci.
43:801-805.

McCluskey, Bill, 1962. Can we crowd too much? Poultry Tribune
68(9):65-66. September.

McDonald, M. W., 1956. The effect of debeaking on the perform-
ance of the chicken. Australian'Veterinary Journal
32:119-122.

McIntosh, J. L., S. J. Slinger, I. R. Sibbald and G. C. Ashton,
1962. The effects of three physical forms of wheat on the
weight gains and feed efficiency of pullets from hatching
to fifteen weeks of age. Poultry Sci. 41:438-445.

Michalson, E. L., 1963. How housing systems compare. Poultry
Tribune 69(9):39,49. September.

Morgan, Walter, 1957. Effect of day-old debeaking on the per-
formance of pullets. Poultry Sci. 36:208-211.

28.

29.

30.

31.

32.

33.

34.

35.

36.

37.

38.

39.

Noles, R. K., J. C. Driggers, C. K. Laurent and W. O. Page,
1962. Floor space requirements of Single Comb White
Leghorn hens. Poultry Sci. 41:887-891

Ostrander, C. E., 1963. How many birds per cage? Poultry
Digest 22(252):l6-l7. February.

Perek, M. and E. Bedrak, 1962. The effect of cold and debeak-
ing upon the adrenal ascorbic acid concentration of chickens
fed aureomycin supplement. Poultry Sci. 41:1149-1156.

Price, F. C., 1959. Debeaking must be done right. Poultry
Tribune 65(10):l4-15,28. October.

Quisenberry, J. H., J. W. Bradley, J. W. Deaton and F. A.
Gardner, 1964. Layer research reports. Feedstuffs
36(19):98,100. May 9.

Shupe, D. W. and J. H. Quisenberry, 1961. Effect of certain
laying house environments on performance of incross egg
production-type pullets. Poultry Sci. 40:1165-1171.

Sink, Archie, 1964. My experiences with colony cages. Poultry
Tribune 70(3):23,56. March.

Slinger, S. J. and W. F. Pepper, 1964. Effects of debeaking and
feeding whole grain on the reproductive performance of
pullets. Poultry Sci. 43:356-362.

Slinger, S. J., W. F. Pepper and l. R. Sibbald, 1962. The
effects of debeaking at eight weeks of age on the grit con-
sumption, weight gains and feed efficiencies of growing
pullets. Poultry Sci. 41:1614-1615.

Vandervort, John, 1962. Reduce losses with proper debeaking.
Poultry Tribune 68(1):l7,38. October.

Vondell, R. H. and R. C. Ringrose, 1957. Debeaking at one day
of age and the feeding of pellets to broiler chickens. 2.
Poultry Sci. 36:1310-1312.

Wilson, H. R. and R. H. Harms, 1964. Crowding caged layers.
Feedstuffs. Jan. 11, p. 20.

‘59-

11
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