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
