• TABLE OF CONTENTS
HIDE
 Front Cover
 Front Matter
 Summary
 Introduction
 Experimental procedure
 Results and discussion
 Literature cited














Group Title: Bulletin - University of Florida. Agricultural Experiment Station ; no. 420
Title: Periodic increase in lighting versus continuous lighting for layers
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00015132/00001
 Material Information
Title: Periodic increase in lighting versus continuous lighting for layers
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 12 p. : ; 23 cm.
Language: English
Creator: Moore, Oscar Keeling, 1916-
Mehrhof, N. R ( Norman Ripley ), b. 1899
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1946
 Subjects
Subject: Poultry -- Housing -- Lighting   ( lcsh )
Poultry -- Effect of light on   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 12.
Statement of Responsibility: by Oscar K. Moore and N.R. Mehrhof.
General Note: Cover title.
Funding: Bulletin (University of Florida. Agricultural Experiment Station)
 Record Information
Bibliographic ID: UF00015132
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000925490
oclc - 18237918
notis - AEN6141

Table of Contents
    Front Cover
        Page 1
    Front Matter
        Page 2
        Page 3
    Summary
        Page 4
    Introduction
        Page 5
        Page 6
    Experimental procedure
        Page 7
        Page 8
    Results and discussion
        Page 9
        Page 10
        Page 11
    Literature cited
        Page 12
Full Text



February, 1946


UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
HAROLD MOWRY, Director
GAINESVILLE, FLORIDA





PERIODIC INCREASE IN LIGHTING
VERSUS

CONTINUOUS LIGHTING FOR LAYERS

By


OSCAR K. MOORE and N. R. MEHRHOF










TECHNICAL BULLETIN











Single copies free to Florida residents upon request to
AGRICULTURAL EXPERIMENT STATION
GAINESVILLE, FLORIDA


Bulletin 420











BOARD OF CONTROL


N. B. Jordan, Chairman, Quincy
Thos. W. Bryant, Lakeland **
M. L. Mershon, Miami
J. Henson Markham, Jacksonville
J. Thos. Gurney, Orlando
J. T. Diamond, Secretary, Tallahassee



EXECUTIVE STAFF

John J. Tigert, M.A., LL.D., President of the
University3
H. Harold Hume, D.Sc., Provost for Agricul-
ture
Harold Mowry, M.S.A., Director
L. O. Gratz, Ph.D., Asst. Dir., Research
W. M. Fifield, M.S., Asst. Dir., Admin.
J. Francis Cooper, M.S.A., Editor3
Clyde Beale, A.B.J., Associate Editor3
Jefferson Thomas, Assistant Editor3
Ida Keeling Cresap, Librarian
Ruby Newell, Administrative Manager3
K. H. Graham, LL.D., Business Managers
Claranelle Alderman, Accountant3



MAIN STATION, GAINESVILLE

AGRONOMY

W. E. Stokes, M.S., Agronomist'
Fred H. Hull, Ph.D., Agronomist
G. E. Ritchey, M.S., Agronomist2
G. B. Killinger, Ph.D., Agronomist
W. A. Carver, Ph.D., Associate
Roy E. Blaser, M.S., Associate5
H. C. Harris, Ph.D., Associate
Fred A. Clark, B.S., Assistant


ANIMAL INDUSTRY

A. L. Shealy, D.V.M., An. Industrialist' 3
R. B. Becker, Ph.D., Dairy Husbandman3
E. L. Fouts, Ph.D., Dairy Technologist3
D. A. Sanders, D.V.M., Veterinarian
M. W. Emmel, D.V.M., Veterinarians
L. E. Swanson, D.V.M., Parasitologist
N. R. Mehrhof, M.Agr., Poultry Husb.3
G. K. Davis, Ph.D., Animal Nutritionist
T. R. Freeman, Ph.D., Asso. in Dairy Mfg.
R. S. Glasscock, Ph.D., An. Husbandman
0. J. Smith, B.S.A., Asst. An. Husb.
P. T. Dix Arnold, M.S.A., Asst. Dairy Husb.3
C. L. Comar, Ph.D., Asso. Biochemist
L. E. Mull, M.S., Asst. in Dairy Tech.
J. E. Pace, B.S., Asst. An. Husbandman4
Katherine Boney, B.S., Asst. Chem.
Ruth Taylor, A.B., Asst. Biochemist
Peggy R. Lockwood, B.S., Asst. in Dairy Mfs.
J. C. Driggers, B.S.A., Asst. Poultry Hush.
W. P. Vaughan, B.S.A., Asst. An. Husb.
W. J. Greene, B.S.A., Asst. An. Husb.


ECONOMICS, AGRICULTURAL

C. V. Noble, Ph.D., Agri. Economist' s
Zach Savage, M.S.A., Associate3
A. H. Spurlock, M.S.A., Associate
Max E. Brunk, M.S., Associate5
Daniel E. Alleger, M.S., Associate
Wade P. Young, Ph.D., Associate

Orlando, Florida (Cooperative USDA)
G. Norman Rose, B.S., Asso. Agr. Economist
J. C. Townsend, Jr., B.S.A., Agri.
Statistican 2
J. B. Owens, B.S.A., Agri. Statistician 2

ECONOMICS, HOME
Ouida D. Abbott, Ph.D., Home Econ.1
R. B. French, Ph.D., Biochemist

ENTOMOLOGY
J. R. Watson, A.M., Entomologist1
A. N. Tissot, Ph.D., Associate3
H. E. Bratley, M.S.A., Assistant

HORTICULTURE
G. H. Blackmon, M.S.A., Horticulturist'
A. L. Stahl, Ph.D., Asso. Horticulturist
F. S. Jamison, Ph.D., Truck Hort.
Byron E. Janes, Ph.D., Asso. Hort.
R. J. Wilmot, M.S.A., Asst. Hort.
R. U. Dickey, M.S.A., Asst. Hort.
Victor F. Nettles, M.S.A., Asst. Hort.
J. Carlton Cain, B.S.A., Asst. Hort.5
F. S. Lagasse, Ph.D., Asso. Hort.2
R. A. Dennison, Ph.D., Asso. Hort.
R. K. Showalter, M.S., Asso. Hort.

PLANT PATHOLOGY
W. B. Tisdale, Ph.D., Plant Pathologist' 3
Phares Decker, Ph.D., Asso. Plant Path.
Erdman West, M.S., Mycologist and Botanist
Lillian E. Arnold, M.S., Asst. Botanist

SOILS
F. B. Smith, Ph.D., Chemist1 3
Gaylord M. Volk, M.S., Chemist5
J. R. Henderson, M.S.A., Soil Technologist
J. R. Neller, Ph.D., Soils Chemist
L. G. Thompson, Ph.D., Soils Chemist
C. E. Bell, Ph.D., Associate Chemist
L. H. Rogers, Ph.D., Associate Biochemist
R. A. Carrigan, B.S., Asso. Biochemist
G. T. Sims, M.S.A., Associate Chemist
H. W. Winsor, B.S.A., Assistant Chemist
Geo. D. Thornton, M.S., Asst. Microbiologist5
R. E. Caldwell, M.S.A., Asst. Soil Surveyor4
Olaf C. Olson, B.S., Asst. Soil Surveyor*
Nathan Gammon, Jr., Ph.D., Soils Chemist
W. W. McCall, B.S.A., Asst. Soil
Microbiologist

1Head of Department.
2 In cooperation with U. S.
3 Cooperative, other divisions,: U. of F.
SIn Military Service.
5 On leave.









BRANCH STATIONS


NORTH FLORIDA STATION, QUINCY

J. D. Warner, M.S., Vice-Director in Charge
R. R. Kincaid, Ph.D., Plant Pathologist
W. H. Chapman, M.S., Asst. Agron.
R. C. Bond, M.S.A., Asst. Agronomist
Frank S. Baker, Jr., B.S.A., Asst. An. Husb.


Mobile Unit, Monticello

R. W. Wallace, B.S., Associate Agronomist


Mobile Unit, Milton

Ralph L. Smith, M.S., Associate Agronomist


Mobile Unit, Marianna

R. W. Lipscomb, M.S., Associate Agronomist


Mobile Unit, Wewahitchka

J. B. White, B.S.A., Associate Agronomist


CITRUS STATION, LAKE ALFRED

A. F. Camp, Ph.D., Vice-Director in Charge
W. L. Thompson, B.S., Entomologist
J. T. Griffith, Ph.D., Entomologist
V. C. Jamison, Ph.D.. Soils Chemist
J. B. Redd, Ph.D., Insecticide Chemist
Harold C. Beard, Ph.D., Chemist
R. F. Suit, Ph.D., Plant Pathologist
E. P. Ducharme, M.S., Plant Pathologist
T. W. Young, Ph.D., Asso. Horticulturist
J. W. Sites, M.S.A., Asso. Horticulturist5
C. R. Stearns, Jr., B.S.A., Asso. Chemist
W. W. Lawless, B.S., Asst. Horticulturist
H. O. Sterling, B.S., Asst. Horticulturist
John A. Granger, B.S.A., Asst. Hort.
B. R. Fudge, Ph.D., Associate Chemist


EVERGLADES STA., BELLE GLADE

R. V. Allison, Ph.D., Vice-Director in Charge
J. W. Wilson, Sc.D., Entomologist4
F. D. Stevens, B.S., Sugarcane Agron.
Thomas Bregger, Ph.D., Sugarcane
Physiologist
G. R. Townsend, Ph.D., Plant Pathologist
B. S. Clayton, B.S.C.E., Drainage Eng.2
Wm. D. Wylie, Ph.D., Entomologist
W. T. Forsee, Jr., Ph.D., Asso. Chemist
F. S. Andrews, Ph.D., Asso. Truck Hort.4
Robt. C. Cassell, Ph.D., Asso. Plant Path.
R. W. Kidder, M.S., Asst. An. Hush.
R. A. Bair, Ph.D., Asst. Agronomist
C. C. Seale, Asst. Agronomist
L. O. Payne, B.S.A., Asst. Agronomist
C. L. Serrano, B.S.A., Asst. Chemist
Earl L. Felix, Ph.D., Asst. Plant Path.
T. C. Erwin, Assistant Chemist


SUB-TROPICAL STA., HOMESTEAD


Geo. D. Ruehle, Ph.D., Vice-Director in
Charge
P. J. Westgate, Ph.D., Asso. Horticulturist
H. I. Borders, M.S., Asso. Plant Path.
D'. O. Waltenbarger, Ph.D., Asso. Ento.
Roy W. Harkness, Ph.D., Asst. Chemist

W. CENT. FLA. STA., BROOKSVILLE

Clement D. Gordon, Ph.D., Asso. Poultry
Geneticist in Charge2

RANGE CATTLE STA., ONA

W. G. Kirk, Ph.D., Vice-Director in Charge
E. M. Hodges, Ph.D., Associate Agronomist
Gilbert A. Tucker, B.S.A., Asst. An. Husb.4
E. R. Felton, B.S.A., Asst. An. Husb.
D. W. Jones, B.S.A., Asst. An. Husb.


FIELD STATIONS

Leesburg

G. K. Parris, Ph.D., Plant Path. in Charge

Plant City

A. N. Brooks, Ph.D., Plant Pathologist

Hastings

A. H. Eddins, Ph.D., Plant Pathologist
E. N. McCubbin, Ph.D., Truck Horticulturist

Monticello

S. O. Hill, B.S., Asst. Entomologist2 4
A. M. Phillips, B.S., Asst. Entomologist2

Bradenton

J. R. Beckenbach, Ph.D., Horticulturist in
Charge
E. G. Kelsheimer, Ph.D., Entomologist
A. L. Harrison, Ph.D., Plant Pathologist
David G. Kelbert, Asst. Plant Pathologist
E. L. Spencer, Ph.D., Soils Chemist
R. O. Magie, Ph.D., Hort., Glad. Inv.
A. J. Pratt, Ph.D., Asst. Hort.

Sanford

R. W. Ruprecht, Ph.D., Chemist in Charge
J. C. Russell, M.S., Asst. Entomologist5
A. A. Foster, Ph.D., Asso. Hort.
B. F. Whitner, Jr., B.S.A., Asst. Hort.

Lakeland

Warren O. Johnson, Meteorologist2

1 Head of Department.
2 In cooperation with U. S.
3 Cooperative, other divisions, U. of F.
4 In Military Service.
6 On leave.



















SUMMARY

1. Birds receiving all-night light laid 2.44 percent more eggs
during the experiment than those receiving an increasing sched-
ule of lighting.
2. A gradual increase in the length of day as administered
the birds in Lot I of this experiment produced a greater initial
response in increased egg production, but after a period it caused
a greater refractoriness to light stimulation than all-night
lighting.
3. Birds of Lot II, receiving all-night lighting, consumed 0.32
pound less feed per dozen eggs than Lot I birds on an increasing
schedule of lighting.
4. Birds in Lots I and II laid eggs in a normal progression
mainly during the daylight hours. The changing schedule of
lighting used in Lot I did not affect noticeably either time of
laying or rhythm of laying.









PERIODIC INCREASE IN LIGHTING VERSUS
CONTINUOUS LIGHTING FOR LAYERS
By
OSCAR K. MOORE and N.-R. MEHRHOF

INTRODUCTION: LIGHT AS A PHYSIOLOGICAL STIMULUS
An important factor in the environment which governs the
reproductive cycle in birds is light, its duration and possibly
its intensity. Egg production in domesticated birds can be
stimulated temporarily during periods of seasonally short day-
light by subjecting the bird to artificial light, giving an increased
length of day in excess of that occurring naturally. Hereditary
characteristics determine the maximum number of eggs a bird
can lay. Environmental characteristics (feed, management,
housing, etc.) determine the actual number of eggs a bird will
lay. The duration and time of occurrence of lighting determine
the seasonal intensity of egg laying and, to a certain extent, the
time of day that the eggs are laid.
Chickens that have not been improved materially by the
technique of selective breeding to increase egg production lay
a relatively high percentage of their annual egg production in
the spring, the increasing length of day serving as the stimulus
to greater reproductive activity. Likewise, semen production
in the male is influenced by length of daylight. Maximum sperm
production has been reported by Parker and McSpadden (3)
to be reached in April and May. The female tends to react
faster to changes in length of day than the male, and conse-
quently, egg laying tends to increase at a faster rate than sperm
proliferation under the influence of lengthening days.
By modifying the natural seasonal incidence of daylight
through the use of artificial illumination in poultry houses the
seasonal distribution of egg and sperm production can be modi-
fied. Higher egg production and better fertility can be secured
in winter by artificially lengthening the day during that season.
Work at the Florida Agricultural Experiment Station indicates,
however, that response to artificial lighting merely changes the
seasonal distribution of egg production. It does not increase
the annual yield of eggs. The latter is determined by hereditary
and environmental factors other than lighting.
Since the eye is a receptor of light, knowledge of the effect
of light upon it will assist in an understanding of the manner







Florida Agricultural Experiment Station


in which light stimulates the reproduction systems of the male
and female. Light entering the eye is believed to start nerve
impulses in the optic system. The optic system comprises the
optic nerve which communicates between the eye and brain.
The optic nerve enters the eye at the retina and carries the
stimulation established by light striking the retina to the brain.
Apparently the brain, when stimulated by the nervous impulses
passing to it by the optic nerve, sends impulses to the pituitary
gland, which in turn secretes the gonadotropic hormones.
The pituitary hormones are secreted into the blood stream
and reach the reproductive organs, the activity of which they
govern. After the gonads (ovary in the female, testes in the
male) have been stimulated by the gonadotropic hormones over
a period of time resulting in prolific egg laying and sperm pro-
liferation in the female and male, respectively, the gonads secrete
a hormone which either depresses further production of the
gonad-stimulating hormone or neutralizes the activity of the
pituitary hormone. Consequently, when birds are subjected
to artificial light in excess of natural daylight, egg and sperm
production are accelerated only for a limited period of time.
After a time when the inhibitive hormones are produced in
sufficient quantity to overcome the stimulative ones, increasing
periods of lighting no longer stimulate egg and sperm produc-
tion. Stimulation is usually followed by a decline in egg pro-
duction below the normal rate.
Lighting systems commonly used where the relative amount
of daylight to darkness is increased result in an increasing rate
of production for a short time only. As an example, egg pro-
duction increases for a time after the length of day is increased,
but after a few weeks the peak of production is reached and
then a rapid decline sets in. It would be of inestimable value
to poultrymen if a lighting system could be devised which would
cause a sustained high rate of egg production.
The purpose of this introduction is to portray the role that light
plays as a physiological stimulus to the reproductive system in
poultry. The eye, brain, pituitary, blood stream and gonads
enter into the series of reactions established by the interception
of light by the eye. Originally it was believed that birds kept
under an unusually long day laid more eggs because the increased
period of lighting allowed more time for feed consumption which
allowed increased rates of laying. This viewpoint is obsolete
(Dakan 2), and the inverse is true. Birds are stimulated directly






Periodic Increase vs. Continuous Lighting


by light, as a result of which they lay more eggs. Because they
are more productive, they eat more feed. Feed and water
consumption are proportional directly to egg production.
The shortcoming in the use of artificial light to increase the
length of daylight and hence stimulate egg and sperm produc-
tion, as practiced by commercial poultrymen, is that lighting
systems in common usage do not give sustained production.
With this thought in mind an experiment was conducted at
the Florida Agricultural Experiment Station in an effort to
maintain egg production by the simple expedient of using a
changing schedule of lighting.

REVIEW OF LITERATURE
Warren and Scott (4) found that light had a psychological
effect upon the time of egg laying. They found that under
conditions of normal lighting birds rarely laid between 5 P. M.
and 6 A. M., but when the day period was darkened and artificial
light provided at night, after about 4 days the birds laid mainly
from 5 P. M. to 6 A. M. They found that hens would lay at any
hour of the day or night under continuous artificial light.
Byerly and Moore (1) conducted an experiment to determine
whether clutch length may be increased by subjecting birds
to alternate light and dark periods totaling 26 hours. The birds
received 14 hours of light and 12 hours of darkness each 26
hours. It was believed that a 26-hour period should produce an
increase in clutch length if darkness is a limiting factor in clutch
length. The rhythmic use of 14 hours light and 12 hours dark-
ness prolonged clutch length without producing refractoriness
to light stimulation.
Whetham's (5) work strongly suggests that "there is some
evidence that stimulus to the pituitary may be caused by changes
in the light ration rather than by the quantitative amount of
light." By studying egg production at different latitudes of
the world, Whetham was led to believe that changes in the
number of hours of light received by chickens, and not so much
the amount of light available, was the primary factor which
causes increased egg production under increasing daylight.
EXPERIMENTAL PROCEDURE
Two lots of Light Sussex pullets were used in this experiment
for each of 3 trials which were conducted for 3 successive years
to determine the lighting schedule most effective for egg pro-







Florida Agricultural Experiment Station


duction. Each lot consisted of 50 pullets at the beginning of
the trial each year. The pullets in each lot were at approxi-
mately the same state of sexual maturity when the trials started.
These trials were started during the month of October.
In Lot I the experimental period for each of the 3 trials was
divided into 14-day intervals in which a changing schedule of
artificial light was used. The first interval of each trial in Lot I
provided no light in addition to the normal length of day. The
second period provided artificial light from 5 A. M. until daylight;
the third from 3 A. M. until daylight; and this schedule of a
2-hour increase per 14 days was followed until the birds received
continuous light. This schedule of increase was chosen arbi-
trarily. Perhaps other time-length combinations would prove
more effective. Eastern Standard Time was used throughout
the 3 trials.
In Lot II the birds were subject to continuous light for the
full length of the experiment. The artificial light was turned
on at 4 P. M. and remained on until 9 A. M. daily. In this man-
ner the birds were never without light. Automatic clocks oper-
ated the lights.
Feeding and management practices were as uniform as pos-
sible in the 2 lots for each successive trial. Both lots of birds
were kept in a single 16' x 25' laying house which was divided
into 2 pens of equal floor area. The partition between the pens
was of light-tight construction. A 40-watt bulb in a 14-inch
procelain reflector was hung above the floor in the center of
each pen. The entire floor area and roosts were flooded with
light. The maximum intensity of light in the pens on a level
with the eye of the bird was 4.8 foot-candles directly under
the light; the minimum intensity was 1.3 foot-candles in the
corners of the pens. (These readings were taken with a G. E.
light meter.)
Trapnest records were kept. The birds were released from
the nests at 2-hour intervals and the time of laying was recorded
when the bird was released, giving a possible maximum in-
accuracy of 2 hours.
Laying mash, grain, grit and shell were available in hoppers
at all times. This induced heavy grain consumption. Each lot
of birds had access to a 50' x 100' yard which provided green
pasturage for at least the first 3 months during each of the
3 trials.
Table 1 shows the lighting schedules used in Lots I and II







Periodic Increase vs. Continuous Lighting


by trials. The start and termination of each trial are indicated
in this table.

TABLE 1.-LIGHTING SCHEDULES OF LOTS I AND II BY TRIALS.
Lot I
Period Light Turned on Lot II
(Time of Day)
1 No artificial light All-night (continuous)
2 5 A.M. All-night (continuous)
3 3 A.M. All-night (continuous)
4 1 A.M. All-night (continuous)
5 11 P.M. All-night (continuous)
6 9 P.M. All-night (continuous)
7 7 P.M. All-night (continuous)
8 5 P.M. All-night (continuous)
9 Continuous All-night (continuous)
10 Continuous All-night (continuous)
11 Continuous All-night (continuous)
12 Continuous All-night (continuous)

RESULTS AND DISCUSSION

Egg production data were calculated by 14-day intervals to
correspond with the increasing lighting schedule given Lot I.
Feed consumption data, on the other hand, were calculated by
28-day intervals as feed was weighed in and out once each 28
days. There were 12 14-day intervals or 6 28-day intervals.
Table 2 gives a summary of percent egg production by 14-day
intervals, lots and trials. Average data for all intervals by lots
and trials are given also. Average data of all trials by lots and
intervals and for all intervals are recorded at the bottom of the
table. The average egg production of Lot I which received the
increasing light periods was 49.27 percent for all trials and all
intervals. The birds in Lot II, receiving all-night light, produced
at the rate of 51.71 percent. Thus, the birds receiving constant
and continuous light yielded 2.44 percent more eggs during the
experiment than those receiving an increasing schedule of light-
ing. Results were uniform in Trials 1 and 2; in Trial 3, when
compared with 1 and 2, there was lack of consistency in results.
In so far as the distribution of egg production is concerned,
after a slightly slower start, egg production tended to reach
a peak faster in Lot I than in Lot II in 2 trials out of 3. A
changing schedule of lighting, consequently, resulted in the
highest stimulatory effect. However, continuing increases in
the length of day did not maintain a high rate of egg production,
since egg production declined more rapidly in every trial in Lot
I than in Lot II. As a result, it may be concluded that a gradual














TABLE 2.-PERCENT EGG PRODUCTION BY 14-DAY INTERVALS BY LOTS, TRIALS AND AVERAGE DATA FOR ALL TRIALS.*

14-Day Intervals Corresponding to Light Increases Given Lot I
SAverage
2 3 4 5 6 7 8 9 10 11 12 All
Intervals

Trial 1, 1941-42
Percent egg production, Lot I...... 37.20 57.59 60.27 55.80 53.89 58.63 48.66 39.29 33.33 17.11 23.00 18.29 41.98
Percent egg production, Lot II.... 38.20 61.02 56.21 46.43 51.71 48.45 47.52 41.46 38.82 45.19 38.66 27.33 45.08
Trial 2, 1942-43
Percent egg production, Lot I...... 35.06 52.27 62.75 72.88 69.05 69.07 67.77 67.94 59.89 53.57 55.54 58.14 60.25
Percent egg production, Lot II.... 51.21 65.71 65.71 70.36 69.29 70.00 68.93 66.07 60.71 59.46 63.15 63.74 64.50
Trial 3, 1943-44
Percent egg production, Lot I..... 25.78 45.12 65.72 66.67 52.53 52.51 45.37 37.07 44.21 41.70 35.98 31.83 45.57
Percent egg production, Lot II.... 26.70 47.84 57.84 60.28 48.95 51.57 46.07 45.89 46.96 42.50 36.13 34.96 45.54
Average of all trials by Lots
Percent egg production, Lot I .... 32.68 51.66 62.19 65.12 58.48 60.07 53.93 48.10 45.81 37.46 38.17 36.07 49.27
Percent egg production, Lot II .. 38.70 58.19 59.92 59.02 56.65 56.67 54.17 51.14 48.83 49.05 45.98 42.01 51.71
_ I __ _


Lot I received a 2-hour increase in length of day at intervals of 14 days until they received continuous light; Lot II received continuous light
throughout the experiment.







TABLE 3.-MASH, GRAIN, TOTAL FEED CONSUMPTION AND POUNDS OF FEED REQUIRED TO PRODUCE A DOZEN EGGS BY 28-DAY
INTERVALS BY LOTS, TRIALS, AND AVERAGE DATA FOR ALL TRIALS.*

28-Day Intervals


Trial 1, 1941-42
Mash Consumption, lbs. per bird..........
Grain Consumption, lbs. per bird........
Total Feed Consumed, pounds ............
Pounds Feed per Dozen Eggs..............

Trial. 2, 1942-43
Mash Consumption, lbs. per bird........
Grain Consumption, lbs. per bird.:......
Total Feed Consumed, pounds..............
Pounds Feed per Dozen Eggs............

Trial 3, 1943-44
Mash Consumption, lbs. per bird........
Grain Consumption, lbs. per bird.......
Total Feed Consumed, pounds..............
Pounds Feed per Dozen Eggs.............

Average of All Trials
Mash Consumption, lbs. per bird .....
Grain Consumption, lbs. per bird........
Total Feed Consumed, pounds.............
Pounds Feed per Dozen Eggs ..............


1 2 1 3


Lot I ILot III Lot I ILot IIi Lot I


1.30 1.26 1.67 1.85 1.92
5.99 5.96 6.95 6.59 6.68
7.29 7.22 8.62 8.44 8.60
6.59 6.23 6.36 7.04 6.55


1.94 1.78
4.24. 4.64
6.18 6.42
6.07 4.64

1.68 1.65
5.78 4.82
7.46 6.47
9.02 7.51

1.64 1.56
5.34 5.14
6.98 6.70
7.23 6.13


2.90
4.61
7.51
4.71


3.47
3.55
7.02
5.22

2.93
5.06
7.99
5.87,


I 4 I 5 6 I Total


Lot III Lot I LotII Lot I Lot II Lot I ILot II Lot I Lot II


1.91 1.73
7.34 6.32
9.25 8.05
7.92 7.85

0 00 A 90


8.23 8.26 7.45
8.56 7.89 7.23

3.20 3.35 2.95
5.13 5.01 4.94
,8.36 8.36 7.89
7.37 7.13 8.89


1.48
6.77
8.25
8.42

4.60


8.02t

22.25
26.69
48.94
5.91t

19.03
28.86
47.89
7.79t-

20.64
27.78
48.42
7.24t


7.56t

23.81
28.47
52.28
5.76t

18.96
26.47
45.43
7.44t

21.39
27.47
48.86
6.92t


Lot I received a 2-hour increase in length of day at intervals of 14 days until they received all-night, continuous light; Lot II received continuous,
all-night light throughout each trial.
** Data lacking.
+ Average.


I







Florida Agricultural Experiment Station


increase in the length of day as administered the birds in Lot I
of this experiment produced a greater initial response in in-
creased egg production, but after a while it caused a greater
refractoriness to light stimulation than did all-night lighting.
Table 3 gives a summary of feed consumption by 28-day inter-
vals, lots and trials. The number of pounds of feed (mash and
grain) consumed to produce a dozen eggs is given also. A sum-
mary of all trials is given at the bottom of the table. Feed
consumption data were not recorded during the 6th 28-day
interval for Trial 1.
The birds in Lot I consumed 20.64 pounds of mash, 27.78
pounds of grain, or a total of 48.42 pounds of feed per bird,
while the birds in Lot II required 21.38 pounds of mash, 27.47
pounds of grain, or a total of 48.86 pounds of feed per bird.
Lots I and II consumed 7.24 and 6.92 pounds of feed per dozen
eggs produced, respectively. Lot II consumed less than a half
pound more feed per bird than Lot I. Lot II, however, con-
sumed 0.32 pound less feed per dozen eggs than Lot I. This
is due to the fact that birds in Lot II laid more eggs than birds
in Lot I.
The time of laying of each egg was recorded on the pen trap-
nest sheets. A study of these data indicates that the schedule
of lighting used for Lot I did not cause any abnormality in the
time of egg laying nor in the rhythm. In both Lots I and II
the first egg of a clutch was laid in the morning. Each suc-
cessive egg was laid from 1 to 2 hours later in the day, on the
average. Long clutches were terminated by the laying of an
egg in the early forenoon. Very few eggs (certainly not above
the normal expectation) were laid after sundown either on the
floor or on the roosts. The nests were closed at-sundown.

LITERATURE CITED
1. BYERLY, T. C., and 0. K. MOORE. Clutch length in relation to period
of illumination in the domestic fowl. Poultry Sci. 20: 387-390. 1941.
2. DAKAN, E. L. Ohio experiment gives new views on lighting. Poultry
Trib. (NE ed.) 40 (Oct.) : 6, 16-17. 1934.
3. PARKER, JESSE E., and B. J. MCSPADDEN. Seasonal variation in semen
production in domestic fowls. Poultry Sci. 22: 142-147. 1943.
4. WARREN, D. C., and H. M. SCOTT. Influence of light on ovulation in
the fowl. Jour. Exp. Zool. 74: 137-156. 1936.
5. WHETHAM, ELIZABETH O. Factors modifying egg production with
special reference to seasonal changes. Jour. Agri. Sci. 23: 383-418.
1933.




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