Effect of Nest-Deprivation on Serum Prolactin Level in ... - CiteSeerX

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Riddle. (1963). Few studies, however, have reported levels of circulating. PRL during the reproductive cycle of birds. Sharp et al. (1979) have ob-. Accepted. May.
BIOLOGY

OF

REPRODUCTION

23,

Effect

118-123

of Nest-Deprivation Level

M.

E.

EL

(1980)

on Serum

in Nesting

HALAWANI,2

Female

W.

H.

Department St.

BURKE

and

of Animal

University

of

P. T.

DENNISON

Science,

Minnesota,

Minnesota

Paul,

Prolactin

Turkeys’

55108

ABSTRACT

Serum

levels of prolactin (PRL), luteinizing hormone (LH), progesterone and estradiol-17t1 were compared in female turkeys during various phases of their reproductive life cycle. Prolactin levels of broody turkeys were higher (2164 ± 127 ng/ml) than those of laying turkeys (468 ± 74 ng/ml), which were in turn higher than those of hens that had stopped laying (119 ± 18 ng/ml). Serum LH, progesterone, and estradiol-17 levels of laying hens were significantly higher than those of the other two groups. The levels of these hormones did not differ between broody hens and hens that had stopped laying, but were not broody (photorefractory hens). Serum prolactin levels of broody hens dropped markedly within a day of nest-deprivation and confinement to cages. Levels remained low while hens were in cages. When nests were again made available to broody hens that had been deprived of nests for 48 h, they resumed nesting within 5 mm, and serum prolactin levels then increased. In other experiments, it was found that a significant decline in serum prolactin occurred after 8, but not 4 h of nest-deprivation. After a 48 h period of cage confinement of hens, prolactin levels were seen to increase within 30 mm after hens were returned to their home pens. Levels continued to rise and had nearly reached pre-cage confinement levels by 12 h after resumption of nesting. INTRODUCTION

Several observations (PRL) involvement in birds: 1) California

served suggest nesting

the

a prolactin behavior of

pituitary PRL is elevated in gulls (Baily, 1952), chickens

PRL

(Cherms et al., 1962); induces nesting in chickens

1935; 3)

Nakajo

nesting

and

doves

Lehrman, has Riddle Few

crop

been

presented

studies,

however, PRL

birds.

have

during

Sharp

et

Accepted May 9, 1980. Received March 24, 1980. This paper is Scientific of

the

Minnesota

Station. 2Correspondence partment St. Paul,

Lehrman

of

in levels

chickens, and Burke

of circulat-

as have Burke and Dennison

of

of

the

present

study

serum

PRL,

progesterone,

and

laying,

nesting,

the

investigate

the

deprivation

on

(1963)

PRL

in nesting

involvement was

estradiol

of PRL

1)

(LII), levels

photorefractory

effects

to:

hormone

and

serum

but

unclear.

undertaken

luteinizing

and

behavior,

are

turkeys; nesting

and

in 2) nest-

levels.

(1963).

of

11,129

determine

1971);

discussion

details The

al.,

in pigeons

Friedmann

by

the

et

Opel,

growth

extensive

an involvement

exogenous

(Riddle

1956; sac

1966;

An

circulating

cycle

Tanaka,

(Hansen, 1968).

subject and

of

and

stimulates

2)

increase

(1980) in turkeys. On the contrary, Etches et a!. (1979) found no differences in PRL levels of laying and broody turkeys. These data support

nesting (Saeki

and Tanabe, 1955; Nakajo and Tanaka, 1956), pheasants (Breitenbach and Meyer, 1959) and turkeys

a significant

ing PRL in incubating and Papkoff (1980)

of MN

Animal 55108.

to:

reported the

al.

(1979)

Journal

Dr.

have

Series

Agricultural

Science,

MATERIALS

levels

M. E. El University

paper

AND

METHODS

Large white female line turkeys in their second laying season were used for these experiments. The birds were ‘\‘17 months of age and weighed ‘\‘8 kg. All birds were hatchmates that had been reared and housed together throughout their life. The hens were housed in floor pens equipped with trap nests. Once a hen entered a nest, she could not get out until released by the caretaker. Nests were checked seven times daily between 0730 and 1700 h, and the presence of each

reproductive ob-

no.

nesting hen was recorded. If an egg was present in the nest with a hen, this was recorded and the egg was removed. At each nest check, any nesting hens were removed from the nests. Thus, the number of times

Experiment Halawani, Deof Minnesota,

each

118

hen

entered

the

nest

each

day

was

known,

and

IN NEST-DEPRIVED

PROLACTIN

TURKEYS

ovarian

activity

assays

records

was

Burke were

as indicated by daily egg production known. Birds were exposed to 54 Iux 15 h with lights on from 0400-1900 h

also

of light for daily. They were given free access to food and water. One or more of the following categories of birds were used in this study depending on the experiment: 1) laying birds that had laid regularly up to the date of the experiment and showed only one or two nest visits per day; 2) nesting birds that were on the nest six or seven times each day for at least 2 weeks without producing eggs, showed aggressive nest-protective behavior when disturbed, and offered pronounced

resistance

to

photorefractory

being birds

dislodged that

from

the

nest; and

3)

had

neither laid nor nested for at least 2 weeks despite the 15L:9D photoperiod and had hard, tight pubic bones and small, dry cloaca that are associated with ovarian quiescence. Nest deprivation was accomplished by separating hens from their nests and placing each hen into an individual wire cage. On the morning of the day of nest-deprivation experiments, turkeys were separated

from their nests and kept nest-deprived for different periods of time depending on the experiment and the treatment. In Exp. 1, daily nesting frequency, serum LH, PRL, progesterone, and estradiol levels were compared laying, samples

photorefractory,

in

1500

for

hormone

and

nesting

determinations

turkeys.

were

Blood

taken

were performed as described by Camper and (1977a). Serum samples for each experiment run in a single assay. The within-assay coefficients of variation were 24.7% for LH, 18.1% for PRL, 23.0% for estradiol, and 10.7% for progesterone. Sensitivities were 0.08 ng for LII, 1.11 ng for PRL, 0.58 pg for estradiol, and 3.94 pg for progesterone.

Statistical

h. In Exp.

Analysis

Data

were

significant

by

variance.

If

means

were

the

using

Least

LTS

I hormone

Serum

their

reproductive

and

serum

various

levels life their

in

significantly

2, nesting turkeys were randomly assigned to two groups. One group remained undisturbed, while the birds of the second group were nest-deprived by placement in individual cages. The birds were bled immediately before nest-deprivation and daily thereafter for 5 days. Serum PRL was determined in samples taken on Days 0, 1, 2, 3, and 5 following

did

not

nest-deprivation. In Exp. 3, nesting turkeys were bled on Days I and 2 (pretreatment) and then randomly assigned to four groups. Birds in Groups 1, 2, and 3 were deprived of nests, and birds in Group 4 were left in their pens as non-deprived controls. Group 1 was returned to their pens after 24 h of deprivation, and Group 2 was returned after 48 h of deprivation. Group 3 remained nest-deprived throughout the experiment. Blood was

nest

and

at

refractory

all.

turkeys

nesting

hens

were

mediate

PRL

levels.

Serum

LU

of

laying

hens

of

nesting

or

PRL

were

lowest,

cycle

visits

were

hens

levels

of

and

and

photo-

those had

levels

than

birds. found levels

those

No

in of

of inter-

estardiol

(P