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I-NCWALL AND KRISTAL
tion and the complete absence of placentophagia to donor
placenta just after parturition (see Table 1). Placentophagia
during parturition was completely eliminated in 2 animals
(placentophagia index of 0.00). Placentophagia scores for
the 6 animals ranged from 0.00 to 0.75, with a mean score
of 0.26 ± 0.12. When Group CP was compared with the
group of females given I AC (Subgroup CP), the difference
in the incidence of placentophagia at parturition was
significant (p = 0.008, by the Fisherexact probability test).
Females in Subgroup CP that exhibited an aversion spent
abnormally long periods of time devoted to attempts at
consuming placenta. While the consumption of placenta in
CP and in normal females was usually completed within I
min after delivery, females exhibiting the aversion would
pick up the placenta, chew vigorously on the attached
unbilicus for several minutes only to drop the placenta,
eventually, on the cage floor. Females would often return
to the placenta after a few minutes and attempt to consume
it once again. During the time devoted to attempts at
placentophagia, the female spent very little time caring for
her litter. Although the females continued to clean the fetal
membranes from their pups, the pups were often observed
scattered about the cage with the umbilicus and placenta
still attached.
Observation о I Maternal Behavior
When observed at 2 days postpartum, all the females in
both pregnant groups (Subgroup CP and Group CP) built
nests, nursed their pups and kept their litter in a single pile
within the nest. Two animals in each of the 2 groups failed
to retrieve their pups during the 15 min retrieval test. In the
group that had exhibited an aversion to placenta at
parturition (Subgroup CP), 4 of the 7 females lost a small
number of pups from the litter size recorded at parturition,
the mean number of pups lost being 2.0 ± 0.7. Although
there was no pup loss observed in the noncontingent LiCI
treatment group (Group CP), the 2 groups were not
significantly different (p = 0.07, Fisher test).
Two week Postpartum Test
During this test (39 days after TAC), all females in both
groups ate placenta. The response of the conditioned group
(CP) was of particular interest. Whereas only I of the 7
animals in this subgroup had eaten placenta at parturition,
all exhibited placentophagia during the 2 wk postpartum
test. This change in response was found to be significant (p
= 0.02: McNemar test).
Response of Nonpreftnant Females (CP)
In the test given to these animals after the control
interval (25 days after TAC), only I of the 7 females
exhibited placentophagia: this was very similar to the
response of the pregnant group (Subgroup CP) at parturi-
tion.
A difference in the expression of the aversion in the
pregnant and nonpregnant groups did appear, however,
when both groups were tested on donor placenta 39 days
after reaching criterion. Whereas 6 of 8 females in the
nonpregnant group (Subgroup CP) were still exhibiting an
aversion to placenta at 39 days, none of the females in the
group that had completed their first parturition (Subgroup
CP) exhibited an aversion to placenta at this time. This
difference was statistically significant (p = 0.006. Fisher
test).
In summary, females conditioned and tested as virgins
(Subgroup CP) expressed an aversion to placenta that was
observable 25 and 39 days after induction. Females
conditioned as virgins and tested at parturition (Subgroup
CP), expressed the aversion to placenta at the first
parturition but not when tested 2 weeks after parturition.
Females given LiCl unpaired with placenta as virgins (Group
CP), did not express an aversion to placenta either at
parturition or 2 weeks after parturition.
EXPERIMENT 2
Experiment 2 was designed to assess the effects of TAC
to placenta induced during the nonpregnant state following
the first pregnancy (prior parturition experience) on the
incidence of placentophagia during the second parturition.
Before the administration of TAC, females in Experiment 2
completed a normal parturition which included the con-
sumption of placenta.
METHOD
Animals
Animals for Experiment 2 were 15 female rats that had
exhibited placentophagia during the pretest.
Procedure
Mating and observations at the first parturition. Within 1
week after the pretest, each virgin female was bred using
procedures described in Experiment 1. On the afternoon of
Day 21 of gestation, females were moved to the testing
room and placed in test cages. They were allowed to
complete a normal parturition, including the consumption
of placenta. Within 8 hr after delivery of the last pup, the
litter was removed and the female returned to her home
cage.
Taste aversion conditioning. One week after parturition,
the taking of vaginal smears to confirm estrous cyclicity
was begun. Two weeks after parturition, LAC was adminis-
tered as in Experiment I.
Mating and observations at the second parturition. Upon
reaching the criterion for taste aversion, the sample was
divided into 2 groups: Group P (pregnant, n = 7), and
Group P (nonpregnant, n = 8). The 2 groups were balanced
for the number of pairings to reach criterion as in
Experiment 1. Females in Group P were mated within 1
week after reaching criterion. During the second parturi-
tion, observation of placentophagia and other perinatal
maternal behaviors was conducted as in Experiment 1.
Females in Group P were not mated.
Observation of maternal behavior and 2 week post-
partum test. Testing procedures were as described in
Experiment 1.
Testing procedures for nonpregnant females. Females in
Group P were given a single exposure to donor placenta 30
days after reaching criterion in TAG. The second control
interval test was administered as in Experiment 1 and took
place 44 days after reaching criterion.
RESULTS
Taste A version Conditioning
Two weeks after the first parturition, all females having
resumed normal estrous cyclicity, females in Experiment 2
were given TAC. The mean number of pairings-to-eriterion