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 Copyright
 Front Cover
 Table of Contents
 Introduction and review of...
 Molting techniques
 Response of various strains to...
 Summary and conclusions
 References
 Back Cover






Title: Forced molting of laying hens
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Permanent Link: http://ufdc.ufl.edu/UF00027303/00001
 Material Information
Title: Forced molting of laying hens
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 22 p. : ; 23 cm.
Language: English
Creator: Wilson, H. R ( Horace Reginald )
Publisher: Agricultural Experiment Stations, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville Fla
Publication Date: 1969
 Subjects
Subject: Molting   ( lcsh )
Chickens -- Experiments   ( lcsh )
Eggs -- Production   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 22).
Statement of Responsibility: H.R. Wilson ... et al..
General Note: Cover title.
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00027303
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: aleph - 003278542
oclc - 60562805

Table of Contents
    Copyright
        Copyright
    Front Cover
        Page 1
    Table of Contents
        Page 2
    Introduction and review of literature
        Page 3
        Page 4
        Page 5
    Molting techniques
        Page 6
        Methods
            Page 6
        Results and discussion
            Page 7
            Page 8
            Page 9
            Page 10
            Page 11
    Response of various strains to molting
        Page 12
        Methods
            Page 12
            Page 13
            Page 14
        Results and discussion
            Page 15
            Page 16
            Page 17
            Page 18
            Page 19
            Page 20
    Summary and conclusions
        Page 21
    References
        Page 22
    Back Cover
        Page 23
Full Text





HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida




BULLETIN 728 (TECHNICAL)


Forced Molting of

Laying Hens

H. R. Wilson, J. S. Moore, A. W. O'Steen
J. L. Fry, and R. H. Harms


Agricultural Experiment Stations
Institute of Food and Agricultural Sciences
University of Florida, Gainesville
J. W. Sites, Dean for Research


FEBRUARY 1969



















CONTENTS

Page

Introduction and Review of Literature ..............------------......... 3
Molting Techniques .--...---...--...------------.. ....----- 6
Methods ..................--- ........................-------- 6
Results and Discussion ..................--....-............--------. 7
Response of Various Strains to Molting- ....--.............-.......... 12
Methods ............ .......---..---------------.-------- 12
Results and Discussion ...----................... ...----- .. -------- 15
Summary and Conclusions ............--............................ ---21
References ...................... .......--------................................... 22







Forced Molting of Laying Hens
H. R. Wilson, J. S. Moore, A. W. O'Steen, J. L. Fry
and R. H. Harms1

INTRODUCTION AND REVIEW OF LITERATURE

Forced molting is the term given any technique or procedure
used to induce a bird to replace its old feathers. In common
usage, it also implies that the hen is induced to stop laying, usu-
ally after 8 to 12 months of production, and remain out of pro-
duction for a few weeks. Molting or the phenomena associated
with it are generally believed to be a period of restoration and
rejuvination of the reproductive system, enabling the hen to
produce eggs subsequently in greater quantity and of better
quality (6)2.
Although forced molting was practiced by a few poultrymen
around 1900, Rice in 1905 (17) was doubtful that the practice
of forced molting laying hens would be profitable. It was his
opinion that the birds should be allowed to lay as long as possible
the first year. More recent opinion's have been variable, and the
advantages and disadvantages have been summarized by Cox in
1964 (6) and Bell in 1965 (4).
Some of the advantages reported for forced molting are:
1. Reduced layer replacement cost per dozen of eggs.
2. Production improved over that of non-molted birds of the
same age.
3. Improved shell quality and albumen quality.
4. Improved feed efficiency.
5. Fewer small eggs.
In addition, forced molting has been reported to improve poor
fertility in turkeys (14), and to increase the DDT (1,1,1-tri-
chloro-2,2-bis [p-chlorophenyl] ethane) depletion rate in hens
(20).
Some of the disadvantages reported for forced molting are:
1. Lower rate of production than in pullet year.
2. More rapid decline in egg quality.
3. Greater percentage of off-grades and defective eggs.
4. Handling problem with high-speed equipment.
5. Oversized eggs may not bring premium price.
6. More disease buildup; mortality may be higher.

1 Associate Poultry Physiologist; Extension Poultryman; Supervisor of
Florida National Egg Laying Test, Chipley; Associate Poultry Products
Technologist; and Poultry Nutritionist and Chairman of Department.
2 Numbers in parentheses refer to References.









Table 1. A selection of methods used for forced molting.
Author and Date Lights Water Feed Drugs, Etc. Other
Poultry Council of Turn off at None for 36 No mash; 6 lbs. grain/100 birds/ None Return birds to laying
the State College start hrs.; One 2 day 1-5 days, then 8-9 lbs. grain house after 8-10 wks.
of Washington, hr. period until molt is finished; at about 2 and use regular lay-
1947 until pro- wks. put on range and feed 2 lbs. ing program
duction mash
stops; ad.
libitum
thereafter
Cox, 1964 Turn off at None for 48- None until birds are out of pro- None Return to full feed
start 72 hours duction; then 1/6-1/4 of normal and regular light pro-
amount for 30-45 days gram
Len, et al., 1964 Turn off at None for None for 31 days; 3 lbs. milo None
start; 14 3/2 days per 100 birds 31/2-6 days; 6 lbs.
hours after milo/100 birds 7-9 days and lim-
4 weeks ited mash 9-10 days; full mash
from 11th day
Marble, 1963 Turn off 10 None for 48 None until production ceased; 12- None
days prior hours 14 lbs. mash/100 birds for 3 wks.
to start; 14 after production ceased then full
hours start- feed
ing 3 wks.
after pro-
duction
ceased
Shaffner, 1955 Normal Normal Normal Progesterone, 20 or
40 mg inj.

Hansen, 1960 Normal Normal Normal Progesterone, 20 mg
inj. or Enheptin-A,
0.15 per cent







7. Houses may be empty if flock becomes unprofitable earlier
than anticipated.
Numerous methods have been used to induce molting in laying
hens. Selected methods are presented in Table 1. The method
most commonly used for inducing a molt has been some varia-
tion of a feed and/or water restriction method such as that sug-
gested by the Poultry Council of the State College of Washington
(19). Noles (15) also reported that feed and water restriction
is an effective method of forced molting.
Progesterone has been shown to be effective in causing a ces-
sation of lay accompanied by a molt (1, 2, 11, 18). The rest
period can be extended with multiple injections of this hormone
(10). Hansen (9) reported higher egg production subsequent to
molts induced by feed and water restriction than with those in-
duced by progesterone. It has also been reported that egg pro-
duction of hens molted with an oral progestin, 6 chloro A"-17-
acetoxy progesterone (CAP), was equivalent to that of birds
molted by feed and water restriction (8).
High levels of dietary iodine have been reported to cause a
cessation of egg production without an accompanying molt (16).
Later studies, however, have indicated that the response to high
iodine may be greater in old birds, as indicated by the effect on
egg production and occurrence of molt in some old hens (3).
Since thyroxine has been reported to induce molting (11), it is
possible that iodine may have some effect through its relationship
with the thyroid gland.
Several methods have been compared in field studies with
various degrees of success (5). The criteria suggested for de-
termining the best molting program were simplicity, low cost, low
mortality, and high egg production following the molt.
Strain and breed differences in response to forced molting
have been suggested by the Poultry Council of the State College
of Washington (19), Marble (13), and Len et al. (12). This
appears to be true for severity of the molt as well as subsequent
performance.
The following experiments were conducted to evaluate: 1)
several molting techniques and their effect on subsequent per-
formance of the birds; and 2) the effect of strain of bird on re-
sponse to molting.







MOLTING TECHNIQUES3


Methods
Experiment 1 began in June with 540 commercial White Leg-
horn hens (Hy Line 934-H) that had completed 10 months of
lay in floor pens. They were randomized into 18 floor pens
(11.1 m2) with 30 birds per pen. The following treatments were
used: 1) control (non-molted) ; 2) water and feed withheld (72
and 168 hours, respectively) ; 3) injected progesterone (one 40
mg intramuscular injection) ; 4) an oral progesterone, 6 chloro
An-17-acetoxy progesterone (CAP),4 fed at the level of 12 gm/ton
of feed for 21 days; 5) CAP fed at the level of 12 gm/ton for 35
days. Two pens of birds on each treatment were fed on a high
protein laying mash (17.00 per cent protein) and two pens (ex-
cept controls) were fed a low protein diet (8.27 per cent protein)
during the 5-week molt period (Table 2).
All birds were fed the high protein laying mash for the 168-
day experimental period following molt. They received 15 hours
of light per day during the entire experiment.
Experiment 2 was conducted with 240 commercial White
Leghorn hens (Heisdorf and Nelson) which had completed 12
months of lay in cages. They were randomized into individual
cages with four replications of six birds each per treatment. The
same molting techniques were used as in Experiment 1, except
for the addition of a low protein control group, and feed was
withheld for 120 hours in the feed and water deprived group.
The birds were maintained for a 35-day molt period, beginning
in September, and a 168-day experimental period. They received
15 hours of light per day during the entire experiment.
Experiment 3 was initiated in May to evaluate high dietary
iodine levels and high initial levels of CAP as molt techniques.
The following treatments were used: 1) control or non-molted;
2) CAP fed at a level of 12 gm/ton for 21 days; 3) CAP fed at
a level of 36 gm/ton for 5 days, then 12 gm/ton for 16 days;
4) 5,000 ppm added dietary iodine (as KI) for 35 days. All
treatments received the 17.00 per cent protein diet (Table 2).
Four replicates of 14 egg production type individually caged
hens were used per treatment. The birds had completed 11
months of lay in cages when the experiment began. The experi-
ment was conducted for a 35-day molt period and 112-day post-
molt period.
Egg production was calculated on a hen-day basis. Livability

3 Portions of this work were previously published (21).
4 Supplied by Elanco Products Company, Indianapolis, Indiana.







MOLTING TECHNIQUES3


Methods
Experiment 1 began in June with 540 commercial White Leg-
horn hens (Hy Line 934-H) that had completed 10 months of
lay in floor pens. They were randomized into 18 floor pens
(11.1 m2) with 30 birds per pen. The following treatments were
used: 1) control (non-molted) ; 2) water and feed withheld (72
and 168 hours, respectively) ; 3) injected progesterone (one 40
mg intramuscular injection) ; 4) an oral progesterone, 6 chloro
An-17-acetoxy progesterone (CAP),4 fed at the level of 12 gm/ton
of feed for 21 days; 5) CAP fed at the level of 12 gm/ton for 35
days. Two pens of birds on each treatment were fed on a high
protein laying mash (17.00 per cent protein) and two pens (ex-
cept controls) were fed a low protein diet (8.27 per cent protein)
during the 5-week molt period (Table 2).
All birds were fed the high protein laying mash for the 168-
day experimental period following molt. They received 15 hours
of light per day during the entire experiment.
Experiment 2 was conducted with 240 commercial White
Leghorn hens (Heisdorf and Nelson) which had completed 12
months of lay in cages. They were randomized into individual
cages with four replications of six birds each per treatment. The
same molting techniques were used as in Experiment 1, except
for the addition of a low protein control group, and feed was
withheld for 120 hours in the feed and water deprived group.
The birds were maintained for a 35-day molt period, beginning
in September, and a 168-day experimental period. They received
15 hours of light per day during the entire experiment.
Experiment 3 was initiated in May to evaluate high dietary
iodine levels and high initial levels of CAP as molt techniques.
The following treatments were used: 1) control or non-molted;
2) CAP fed at a level of 12 gm/ton for 21 days; 3) CAP fed at
a level of 36 gm/ton for 5 days, then 12 gm/ton for 16 days;
4) 5,000 ppm added dietary iodine (as KI) for 35 days. All
treatments received the 17.00 per cent protein diet (Table 2).
Four replicates of 14 egg production type individually caged
hens were used per treatment. The birds had completed 11
months of lay in cages when the experiment began. The experi-
ment was conducted for a 35-day molt period and 112-day post-
molt period.
Egg production was calculated on a hen-day basis. Livability

3 Portions of this work were previously published (21).
4 Supplied by Elanco Products Company, Indianapolis, Indiana.







Table 2. Composition of diets.


Calculated Per Cent of Diet
Ingredient 17.00% protein 8.27% protein
Yellow corn meal 67.73 91.90
Soybean meal (50% protein) 20.60 -
Alfalfa meal (20% protein) 3.00 -
Ground limestone 5.81 6.00
Defluorinated phosphate 1.96 1.20
(18% P and 32% Ca)
Iodized salt 0.40 0.40
Micro-ingredients1 0.50 0.50
Kcal/Kg (PE) 2017 2233

'Supplied per kg diet: 6600 IU vitamin A; 2200 ICU vitamin D3; 2.2 mg vitamin K
(MSBC) ; 4.4 mg riboflavin; 13.2 mg pantothenic acid; 39.6 mg niacin; 499.4 mg choline;
22 mcg vitamin B12; 125 mg ethoxyquin; 19.8 mg iron; 1.98 mg copper; 198 meg cobalt; 1.1
mg iodine; 99 mcg zinc; 83.6 mg manganese.


was calculated and expressed as per cent of potential hen-days
(number birds started X number days) days lost due to deaths
S(number birds started number days). Egg quality (Haugh
units, shell thickness, and egg weight) was measured monthly
and reported as an average of 6 post-molt measurements in Ex-
periments 1 and 2. Egg quality was measured at the end of the
112-day post-molt period in Experiment 3. Body weight gain
was calculated on weight change from the start to the end of the
study.
Data were subjected to analysis of variance and Duncan's (7)
multiple range test where appropriate.

Results and Discussion
In Experiments 1 and 2, all molt techniques were effective in
inducing a feather molt. Injected progesterone caused the most
severe molt and the most immediate and pronounced effect on
egg production (Table 3). The percentages of birds in Experi-
ment 2 which were out of production for at least one week during
the molt period were 17, 79, and 96 per cent for the controls on
high protein mash, controls on low protein, and those fed CAP
for 21 days with high protein mash, respectively. Other treat-
ments caused all birds to be out of production for one week or
more. The low protein diet increased the severity of the molt
and extended the rest period. Feeding the low protein diet with-
out additional treatment caused a partial molt and decreased egg
production in Experiment 2.














Table 3. Egg production during and following force molt treatments.


Treatment1


Molt Period (35 days)
Exp. 1 Exp. 2 Average


C-LP2
WF-S
oo WF-LP
IP-S
IP-LP
CAP 21-S
CAP 21-LP
CAP 35-S
CAP 35-LP


Egg Production (Per Cent Hen Days)
Post-Molt (168 days)
Exp. 1 Exp. 2 Average
49.2 52.2 50.7
53.1 -


23.0
6.0
7.4
0.8
15.4
12.4
11.8
8.4


Molt and Post-molt
Exp. 1 Exp. 2 Average


- 47.3
53.8 52.4
52.0 52.1
49.5 49.0
47.8 43.7
51.6 51.7
52.3 53.6
49.9 45.4
49.6 51.5


'Key: C=control, WF=feed and water withheld, IP=injected progesterone, CAP 21=CAP fed for 21 days, CAP 35=CAP fed for 35 days, S=17.00%
protein mash, LP=8.27% protein mash.
2Not included in Experiment 1.








Table 4. Livability and body weight gain during combined molt and
post-molt.

Livability' (%) Body Weight Gain' (gm)
Treatment2 Exp. 1 Exp. 2 Average Exp. 1 Exp. 2 Average
C-S 93.7 95.6 94.6 189 74" 131.5
C-LP 95.6 144a' -
WF-S 94.5 92.2 93.4 215 2260 220.5
WF-LP 86.9 89.3 88.1 140 1261b 133.0
IP-S 91.1 97.5 94.3 222 213bc 217.5
IP-LP 78.8 83.2 81.0 168 202b" 185.0
CAP 21-S 91.3 92.2 91.8 108 224' 166.0
CAP 21-LP 82.1 96.6 89.4 183 181b" 182.0
CAP 35-S 93.0 90.3 91.6 236 213b' 224.5
CAP 35-LP 82.8 97.2 90.0 204 1340b' 169.0
'Means having the same superscripts are not significantly different (P<.05).
2See footnote 1, Table 3.

All molted groups laid at a higher rate than controls during
the 168-day post-molt period (Table 3) ; however, the differences
were not statistically significant. With the exception of the
progesterone injected groups, those groups which had received
low protein during the molt period laid at a higher rate than
those which had received the high protein mash. The highest
peak in production following molt was 75 per cent for a 1-week
period and 70 per cent for a 4-week period.
Total egg production during the combined molt and post-molt
periods did not differ significantly from that of controls. It
would appear that an increased egg production rate would need
to be maintained beyond 6 months post-molt to give forced molt-
ing an advantage in total number of eggs produced.
There were no significant differences in livability due to treat-
ment when it was expressed as per cent of potential hen-days
(Table 4). There was considerable variation between replicates
within treatments, especially in Experiment 1 in which an out-
break of cannibalism occurred in some groups fed the low protein
diet.
Body weight gains during the experimental period tended to
be greater for those groups given the 17.00 per cent protein diet
during the molt period (Table 4). Most birds lost weight during
the molt period and gained at a faster rate than controls after
the molt. The birds fed CAP for 21 days and the low protein
diet lost significantly more weight during the molt period than
all other treatments in both experiments.














Table 5. Feed consumption during molt and post-molt periods.


Feed/Bird/Day (gm)
Exp. 2


Molt Post-Molt 1 wk. 2 wk. 3 wk. 4 wk. 5 wk. Av(Molt) Post-Molt


2.0 95.7 71.7 83.5 91.6 88.9
- 60.8 63.0 50.8 53.5 46.3
9.3 85.3 78.0 82.1 91.6 91.6
5.2 70.8 70.3 64.9 60.8 58.1
1.6 93.0 64.9 59.4 67.6 68.9
2.4 77.6 47.6 40.4 36.3 31.3
6.6 87.5 67.6 71.7 67.6 60.8
7.0 70.3 68.9 75.8 71.7 43.1
'5.7 86.2 70.3 80.7 79.4 62.6
'7.5 74.4 67.6 79.4 70.3 62.1


Treatment'


Exp. 1


C-LP
WF-S
SWF-LP
IP-S
IP-LP
CAP 21-S
CAP 21-LP
CAP 35-S
CAP 35-LP


11


9
13
12
14
9
10
9
10


'See footnote 1, Table 3.


96.2
98.0
105.7
107.5
97.1
109.3
98.9
100.7
100.7
96.2














Table 6. Egg quality characteristics following forced molting.

Egg Weight Albumen Quality Shell Thickness Blood and Meat Spots
(gm) (Haugh Units) (mm)l (per cent)
Treatment2 Exp. 1 Exp. 2 Avg. Exp. 1 Exp. 2 Avg. Exp. 1 Exp. 2 Avg. Exp. 1 Exp. 2 Avg.
C-S 62.0 62.7 62.4 60.8 64.9 62.9 .358" .376 .367 10.3u 11.5 10.9
C-LP 63.6 69.5 .368 7.2 -
WF-S 61.9 63.9 62.9 64.2 68.0 66.1 .364b .361 .362 10.0" 8.3 9.2
- WF-LP 61.3 63.7 62.5 62.1 71.5 66.8 .3700 .363 .367 3.1t 8.3 5.7
IP-S 61.0 63.3 62.2 64.2 69.3 66.8 .366b .368 .367 2.6t 6.2 4.4
IP-LP 61.4 63.5 62.4 63.1 69.3 66.2 .3730 .386 .380 4.2t 6.0 5.1
CAP 21-S 60.5 62.8 61.6 64.1 67.6 65.9 .373' .371 .372 3.2t 7.8 5.5
CAP 21-LP 60.2 63.6 61.9 63.4 69.7 66.6 .366b .363 .364 3.6t 9.6 6.6
CAP 35-S 60.6 62.6 61.6 65.6 71.6 68.6 .368b .376 .372 5.2t 9.2 7.2
CAP 35-LP 60.4 62.8 61.6 63.8 69.9 66.9 .366b .366 .366 4.2t 4.8 4.5

'Means having the same superscripts are not significantly different (P<.05).
-See footnote 1, Table 3.







Feed consumption was not measured separately for replicate
groups, and therefore was not statistically analyzed. The treat-
ment data suggested that hens which received the high protein
diet consumed more feed (Table 5) during the molt period than
the groups which received the low protein mash (71.8 vs. 59.0
gms and 77.9 vs 60.8 gms in Experiments 1 and 2, respectively).
There was also a tendency for consumption to be higher follow-
ing molt in those groups which had been fed low protein during
the molt period. Feed consumption during the molt period is in-
fluenced by two factors: egg production and energy level of the
feed. Following molt it is influenced by egg production and
weight gain.
There were no significant differences in egg weights due to
molting treatments, although there appeared to be a slight re-
duction in those groups which received CAP (Table 6). This
finding agrees with the lack of effect on egg weight reported by
Len et al. (12) and Noles (15).
Albumen quality (Haugh units) was numerically increased
by molting, but the difference was not statistically significant
(Table 6). Shell thickness was increased significantly by molt-
ing in Experiment 1, but there were no significant effects in
Experiment 2 (Table 6). The incidence of blood and meat spots
did not appear to have been affected by molting (Table 6) a's
previously reported (13). However, when compared with pre-
molt levels, the controls and molted groups increased 60 and 110
per cent respectively, indicating a possible effect due to molting.
In Experiment 3, egg production following the molt reached
a peak higher than controls, but average production was less
(Table 7) for the 112-day period. All molted groups were lay-
ing at a higher rate than controls at the end of the experiment.
The birds treated with a high level of CAP for 5 days and those
treated with iodine recovered more slowly. In contrast to re-
ports (3, 16) using young birds, iodine caused a considerable
molt in this experiment using old hens.
Egg weights and Haugh units were affected very little by
molting (Table 7). Shell thickness was improved slightly by
molting with CAP, but there was no apparent improvement from
iodine.

RESPONSE OF VARIOUS STRAINS TO MOLTING
Methods
This experiment was conducted at the Florida Random
Sample Test, Chipley, Florida, using 8 commercial egg produc-
tion stocks (Table 9). The stocks had just completed the 400 day
12







Feed consumption was not measured separately for replicate
groups, and therefore was not statistically analyzed. The treat-
ment data suggested that hens which received the high protein
diet consumed more feed (Table 5) during the molt period than
the groups which received the low protein mash (71.8 vs. 59.0
gms and 77.9 vs 60.8 gms in Experiments 1 and 2, respectively).
There was also a tendency for consumption to be higher follow-
ing molt in those groups which had been fed low protein during
the molt period. Feed consumption during the molt period is in-
fluenced by two factors: egg production and energy level of the
feed. Following molt it is influenced by egg production and
weight gain.
There were no significant differences in egg weights due to
molting treatments, although there appeared to be a slight re-
duction in those groups which received CAP (Table 6). This
finding agrees with the lack of effect on egg weight reported by
Len et al. (12) and Noles (15).
Albumen quality (Haugh units) was numerically increased
by molting, but the difference was not statistically significant
(Table 6). Shell thickness was increased significantly by molt-
ing in Experiment 1, but there were no significant effects in
Experiment 2 (Table 6). The incidence of blood and meat spots
did not appear to have been affected by molting (Table 6) a's
previously reported (13). However, when compared with pre-
molt levels, the controls and molted groups increased 60 and 110
per cent respectively, indicating a possible effect due to molting.
In Experiment 3, egg production following the molt reached
a peak higher than controls, but average production was less
(Table 7) for the 112-day period. All molted groups were lay-
ing at a higher rate than controls at the end of the experiment.
The birds treated with a high level of CAP for 5 days and those
treated with iodine recovered more slowly. In contrast to re-
ports (3, 16) using young birds, iodine caused a considerable
molt in this experiment using old hens.
Egg weights and Haugh units were affected very little by
molting (Table 7). Shell thickness was improved slightly by
molting with CAP, but there was no apparent improvement from
iodine.

RESPONSE OF VARIOUS STRAINS TO MOLTING
Methods
This experiment was conducted at the Florida Random
Sample Test, Chipley, Florida, using 8 commercial egg produc-
tion stocks (Table 9). The stocks had just completed the 400 day
12








Table 7. Egg production and egg quality
and iodine.


of birds molted with CAP


Hen-Day Prod.
(per cent)


Egg Wt.


Albumen
Quality
(Haugh


Shell
Thickness


Treatment Molt+ Post-molt1 (gm) Units) (mm)
Control 43.10 59.6 69.3 .348
CAP 21 days
(12 gm/ton) 41.2b" 59.1 70.5 .363
CAP 5 days
(36 gm/ton)-
16 days (12 gm/
ton) 34.4ab 59.4 71.4 .366
I, 35 days
(5000 ppm) 33.2a 59.4 70.0 .348
'Means having the same superscripts are not significantly different (P<.05).


test period in floor pens and were selected at random for the
study from those strains having sufficient healthy survivors.
During the pullet-year laying phase, one half of the birds in each
stock had been fed an all mash diet (diet 1, Table 8) while the
other half had been fed a mash concentrate (diet 2, Table 8) and
whole corn. Both diets were fed ad libitum.
Culling prior to molting was limited to birds which were obvi-
ously sick or unthrifty. Three groups of 24 birds each were se-
lected at random from those birds of each strain which had been
fed all mash, and 3 groups of 24 birds each were selected from


Table 8.


Ingredient
Yellow corn
Soybean meal (44% protein)
Meat scraps (55% protein)
Fish meal (60% protein)
Alfalfa (17% protein)
Iodized salt
Ground limestone
Defluorinated phosphate (18%
Vitamin mix1
Mn SO,


Composition of diets.


Per Cent of Diet
Diet 1 Diet 22
67.6 7.4
13.1 37.4
5.0 14.3
2.5 7.1
5.0 14.3


P and 32% Ca)


'Supplied per kg diet: 4400 IU vitamin A; 748 ICU vitamin D3; 2.2 mg riboflavin; 9.9
mg niacin ; 4.0 mg pantothenic acid; 6.6 mcg vitamin Bi2; 550 mg choline.
'Fed with whole corn.
















Table 9. Egg production of strains (per cent hen-day).1


Molt

3.7ab
3.3ab
4.5b
3.2ab
3.9ab
2.7a
2.8'
2.7a


Post-molt

59.6"ab
60.2abed
59.2ab
64.7de
68.8e
63.8bed
58.2'
60.5"abd


Post-Molt
Molt+ After 50%
Post-molt Level Reached


49.2ab
50.1abe
49.4"b
53.9Cd
57.3d
53.1be
48.2"
50.0ob"


65.1ab
65.4ab
63.7"
71.1ed

74.4"
69.0bc

64.3ab
66.9"ab


One Week
Peak

73.8
76.1
75.4
79.7
82.6
77.8
75.0
75.1


Average 68.8 3.4 61.9 51.4 67.5 77.0

'Values having the same superscripts are not significantly different (P<.05).
Strains were as follows: 1-H & N "Nick Chick"; 2-True Line #365-B; 3-Babcock B-300; 4-Kimber K-137A; 5-Shaver Starcross 288; 6-Hy-Line
Hy-934D; 7-Garber G-200; 8-Honegger Layer.


Strain2

1
2
3
4
5
6
7
8


Pullet

67.9ab
66.5a
71.3 b
70.0abe
73.4e
68.2ab
66.5'
67.1"







those which had been fed mash concentrate and whole corn. A
total of 1152 birds, 144 birds per strain, were molted. The hens
were moved from the floor pens into 10 X 18 inch laying cages
with one bird per cage. The 35-day molting period began immedi-
ately when the birds were placed in cages (November) with no
feed, water or supplemental light. They received natural daylight
from 0 to 35 days. Water was provided after 72 hours and the
molting diet (8.27 per cent protein, Table 2) after 168 hours.
Both were furnished ad libitum. At the end of the 35-day molt-
ing period the birds were given supplemental light to a total of
16 hours of light per day, and changed from the molting diet to
a laying diet (diet 1, Table 8).
Egg production, livability (per cent potential hen-days), feed
conversion, Haugh units, shell thickness, egg size, and income
data through 168 days post-molt were compared between strains
and with pullet data. The data were subjected to analysis of
variance, Duncan's (7) multiple range test, and correlation an-
alysis where appropriate.

Results and Discussion
Egg Production
Egg production declined to zero in all strains at an average
of 3.8 to 5.5 days after they were placed on the molting diet. The
induction of a feather molt was effective in all 'strains. Initiation
of the molt was probably aided by moving the birds from floor
pens to cages. Egg production was very low during the molting
period (Table 9) and most of these eggs were laid in the first
4 days. Strain variations were apparent in molting period pro-
duction. Molting period production was positively, but not sig-
nificantly, correlated (+.482) with pullet-year production (Table
10). There was a significant (P<.05) interaction between
strains and pullet-year feed regime in respect to molt period
production. Strain 3 birds which were fed mash during the
pullet-year laid significantly more eggs than those which had
been fed corn, while the reverse was true for strain 5.
Egg production reached 50 per cent at 52.9 days after the
start of the molt, ranging from 50.8 days for strain 3 to 55.5 days
for strain 7 (Table 11). Strain 3 birds matured earliest in the
pullet year, laid at one of the highest rates during the pullet year
(Table 9), and were most resistant to the molt technique (4.5
per cent production during the molt period), but responded poor-
ly to molting by laying only 59.2 per cent in the post-molt periods.
On the other hand, strain 5 birds matured early in the pullet-year,
laid at the highest rate in the pullet-year, were moderately re-







Table 10. The correlation of various traits in molted birds.

Associated Variables Correlation'
Pullet-year production and molt period production +.482
Pullet-year production and post-molt production +.436
Pullet-year production and molt+post-molt production +.383
Pullet-year production and days to 50% post-molt production -.199
Pullet-year production and per cent extra-large eggs
(pullet year) +.097
Post-molt production and per cent extra-large eggs (post-molt) +.233
Days to 50% production-pullet and molt +.778**
Albumen quality (Haugh units)-pullet and post-molt +.896**
Shell thickness-pullet and post-molt +.625**
Income and molt+post-molt production +.906**
Income and molt+post-molt feed conversion -.801**
Income and per cent medium eggs (post-molt) -.212
Income-pullet year and molt year +.156

'Significance (P<.01) indicated by **.


sistant to the molt, and laid at the highest rate following molt
(68.8 per cent). Although pullet-year production was positively
correlated ( .436) to post-molt production (Table 10), it did
not appear to give assurance of a good response to molting. This
correlation is in agreement with that (+.54) reported previous-
ly (13). There was a high correlation (+.778) for time to 50
per cent production for the pullet-year and the molt-year, indi-
cating that a flock which matured early could be expected to be-
gin production early following a molt.

Livability
Hen-day livability varied little among strains (Table 11).
Strain 1 livability was slightly lower and just reached significance
at the .05 level. With a criterion such as livability, which is nor-
mally quite variable, in addition to the low level of significance,
care should be taken in interpreting these results.

Egg Quality
Significant differences in Haugh unit scores were found among
strains in both pullet and molt years (Table 12). Scores during
the molt year averaged 2.5 Haugh units lower than during the
pullet year. There was a very high correlation, +.89, of Haugh
unit scores in the molt year with those obtained during the pullet-








Table 11. Time required to reach 50 per cent production and mortal-
ity rates during the pullet and molt-years.

Time to 50 Per Cent Production Livability
(Days)1 (Per Cent PHD)1,2
Strain Pullet Year Molt Year
(age) (from start of molt) Molt
1 168 53.3ab" 91.3'
2 170 52.7"b 96.1b
3 164 50.8" 97.4b
4 168 53.3abe 97.3b
5 166 51.5ab 97.2b
6 173 52.0'b 94.4"b
7 174 55.5' 94.2ab
8 173 54.0b' 93.2ab

Average 170 52.9 95.1

'Values having the same superscripts are not significantly different (P<.05).
2Potential hen days.

Table 12. Egg quality during pullet year and molt year.

Albumen Quality (Haugh Units)1 Shell Thickness (mm)1
Strain Pullet2 Post-molt3 Pullet2 Post-molt3
1 84.0' 81.7b .367a .366'b
2 81.8d 77.3' .372'b .372bc
3 79.2ab 76.8a .372" .365ab
4 85.2' 83.8' .384d .376
5 79.8b" 77.8' .373'b" .370abc
6 78.0' 76.8" .374b' .363'
7 84.2' 81.8b .3790d .374'
8 80.8d' 77.0" .374"b .372bC

Average 81.6 79.1 .374 .370
'Values having the same superscripts are not significantly different (P <.05).
2Average of four evaluations during year.
3Average of four evaluations after molt (60, 112, 162, and 199 days from start of molt
period).

year. This value agrees with that of Marble (13), +.81, who
stated that scores during the pullet-year could be used to predict
albumen quality for the hen year.
Shell thickness varied among strains in the molt-year as well
as the pullet-year (Table 12) and averaged .004 mm less during
the molt-year. A correlation value of +.625 for pullet year and
molt year shell quality compares with that of +.74 reported pre-
viously (13).
















Table 13. Egg size during pullet year and molt year (per cent of all eggs laid).


Molt+ Post-MoltI


Extra
Strain Large Large Medium


1
2
3
'- 4
00
5
6
7
8


24.8"bo
17.4a
27.6bed
22.21b
33.8e'
35.9d
29.8b'd
26.2"bc


18.4"b

27.0'
19.4"b
23.0bO
14.4a
14.5"
17.5"I
17.4b"


Pullet Year'


Peewee

1.3ab
2.8d
2.3'
1.6b

1.1a
0.91
1.01


Extra
Large

75.2b"
62.6'
70.6b
68.8ab

84.2"
83.0d
77.7'd
79.2'd


Average 27.2 52.4 19.0 1.5 75.2

IValues having the same superscripts are not significantly different (P<.05).


Large

24.4be
35.3d
28.8ed

30.1'd
15.5"
16.8"
21.0b
20.55b

24.0


Medium

0.4ab
1.81
0.5-b
1.1ab"

0.3ab
0.2'
1.2b

0.2"

0.7


Small+
Peewee

0.1
0.3
0.0
0.0
0.0
0.0
0.1
0.0


---


small-r







Egg size varied significantly among strains during the molt
year (Table 13), ranging from 62.6 per cent extra large in strain
2 to 84.2 per cent in strain 5. Large and extra large eggs com-
posed more than 99 per cent of all eggs during the molt-year, as
compared to 80 per cent during the pullet-year. It is of interest
that there were no significant strain differences in per cent large
eggs during the pullet-year. Though, there were significant dif-
ferences in per cent extra large eggs which were reflected in
changes of per cent medium eggs.

Feed Conversion
The feed required to produce a kilogram of eggs was greater
in molted birds than in pullets (Table 14), when the molt period
was included. Similar results have also been reported by Len
et al. (12). On the other hand, total feed consumption has been
reported to be less in molted birds than in pullets (13). Since
molted flocks do not gain as much body weight and lay fewer
eggs than pullets, a reduced feed consumption would be expected.
The larger egg size of molted birds tends to partially off-set the
low production rate. Feed conversion would be expected to im-
prove in molted flocks also because of the lower requirement for
body weight gains; however, the advantage is more than offset
by the lower rate of egg production, and possibly a higher main-
tenance requirement. It should be pointed out that in the present
experiment pullet-year feed consumption was measured during
the entire year, while molt-year feed consumption was measured
from the first of December through June. Feed consumption
could therefore be expected to be greater for the molted birds,

Table 14. Feed conversion during pullet and molt year.

Kg Feed/Kg Eggs'
Strain Pullets Post-molt Molt+Post-molt
1 2.8 2.8b 3.2c
2 2.8 2.8b 3.1b"
3 2.6 2.8b 3.1b"
4 2.7 2.7ab 3.0ab
5 2.7 2.6" 2.9a
6 2.8 2.6" 3.0ab
7 2.8 3.0 3.4d
8 2.8 2.8b 3.2'
Average 2.8 2.8 3.1
'Values having the same superscripts are not significantly different (P<.05).







since this period included the cold season which causes greater
feed intake.
Strain differences were apparent in feed conversion for the
molt and post-molt period with strains 1, 7, and 8 being least
efficient and strain 5 most efficient (Table 14). Strain 5 started
laying early after molting, had the highest egg production rate,
and laid larger eggs, all of which are determining factors of feed
efficiency.

Income
Income for the pullet-year was calculated as value of eggs and
meat produced minus feed and chick costs. Income for molted
birds was calculated as value of eggs and meat minus feed costs
and meat value of the birds at the end of the pullet-year. Income
from the molted flock was also compared with the income over
the same time period for the replacement pullet flock. This per-
mits a comparison of the income from the molted birds and the
income which could have been expected if they had been replaced
with a pullet flock of the same strain.
Significant differences in income were found between strains
in both the pullet and molt-years (Table 15). Molt-year income
was not closely correlated (r- +.156) to pullet-year income
(Table 10). Molt-year income was very closely correlated to
molt + post-molt egg production (r= +.906) and feed conversion
(r =-.801).
Many other factors must be considered, however, in a com-
plete economic analysis. Some of these factors would be flock de-

Table 15. Income over costs during pullet and molt years.

Income Over Costs (Cents/Bird)
Strain Pullet Year1 Molt Year1 Pullet Year2
1 458abe 124" 130
2 424a 141." 141
3 505e 138"b, 146
4 484b' 160cd 129
5 504' 172" 142
6 438"b 150bed 147
7 442"a 119, 125
8 438"b 131ab 120
Average 462 142 135
'Values having the same superscripts are not significantly different (P<.05).
2Income from the pullet flock which replaced the molted flock in floor pens. The data
covers only that period of time which coincides with the molt year of the molted birds.







preciation, losses due to poorer shell and albumen quality, pos-
sible premiums due to large egg size, efficient utilization of houses
and equipment, disruption of replacement program, and effect
on or possible loss of market.
Income data reported here apply only to the situation in
which the experiment was conducted and give only a limited
comparison of strains, and pullet and molt-year performance.
Any projection of the possible economic value of initiating a
molting program must be based on the projected economic situa-
tion for that period.

SUMMARY AND CONCLUSIONS
The data presented in these studies indicate that forced molt-
ing may be used under favorable conditions to partially restore
egg production rate. Albumen quality and shell quality may be
improved, but results were not consistent and differences were
not large. Larger egg size may partially offset deficiencies in
egg production and egg quality as compared to pullet flocks. The
data indicate that 6 or 7 months of post-molt production are
necessary to overcome production lost during the molt period.
It is evident from the production data that to obtain a com-
petitive and profitable production in molted birds it is necessary
to have birds which respond well to molting treatment, return to
production quickly, peak at a high level, and maintain a high
level of production after 50 per cent production is reached.
Before forced molting is used as a management practice, a
thorough examination should be made of the market situation,
pullet flock performance and efficiency of equipment and housing
utilization.
The method of choice for a practical forced molting program
would be:
1. Cull birds prior to starting the molt.
2. Turn off supplemental light, or provide decreasing light.
3. Withhold water for 3 days and feed for 7 days.
4. Feed a low protein diet (8.27 per cent protein diet, Table
2) for 4 weeks.
5. Return birds to normal laying mash and light regime 35
days after the start of the program.
A method utilizing progesterone would appear to be satis-
factory, but one using iodine would not be recommended.








REFERENCES
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842.
19. The Poultry Council of the State College of Washington. 1947. Sum-
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20. Wesley, R. J., A. R. Stamp, B. J. Liska, and W. J. Stadelman. 1966.
Depletion of DDT from commercial layers. Poultry Sci. 45:321-324.
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Performance of hens molted by various methods. Poultry Sci. 46:
1406-1412.

















































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