The name is absent

Placentophagia and taste aversion conditioning

placed with a breeder male. Vaginal smears were obtained
every morning until sperm in the vaginal smear or a vaginal
plug was observed (Day 1 of pregnancy).

Observations at the first parturition. Pregnant females of
Subgroup CP and Group CP were moved to the
testing room on the afternoon prior to the expected date of
parturition (Day 22). (The unequal group sizes are ac-
counted for by the removal, at this point, of females failing
to become pregnant.) Each female was placed in a test cage;
food, water, and a paper towel for nest-building were
provided. The testing room was maintained on a light-dark
cycle synchronized with that of the colony room. A 40 W
red light bulb provided illumination during the dark period.
Beginning at 9:00 the next morning, each pregnant female
was checked at 30 min intervals until she began to deliver.
The entire parturition was observed and notes were taken
on perinatal behavior with special emphasis on placento-
phagia.

Thirty min after delivery of the last pup, the litter was
removed from the cage. Unattached placentas were also
removed and counted. The litter was inspected to deter-
mine whether the pups had been cleaned and the placentas
detached. The litter was placed uder a 75W white incandes-
cent bulb to provide warmth. To assess the expression of an
aversion to placenta in the parturition tests only, a
Placentophagia index was computed by dividing the num-
ber of consumed placentas by the total number of placentas
delivered.

Immediately after the removal of the litter, the female
was presented, for 15 min, with 4 donor placentas in a
specimen dish. Then, the litter was reintroduced into the
cage and the female’s latency to retrieve all pups to the nest
site was recorded. The mesh grid was then removed, and
coarse sawdust placed in the cage for nestbuilding. The cage
containing the female and her litter was moved to a metal
rack in the testing room.

Observations of maternal behavior at 2 days postpartum.
Two days after parturition, the female was tested for
several general indices of maternal behavior: the presence of
a well-built nest, the number of surviving pups, and the
arrangement of the litter. The litter was then scattered
around the cage floor and the female’s latency to retrieve
the litter to the nest site was recorded: if the female did not
retrieve her litter during a 15 min test period, she was
recorded as not having exhibited retrieval. The litter was
then removed and the female returned to her home cage.

Placentophagia test at 2 weeks postpartum. Another
measure of placentophagia of donor placenta was taken 2
weeks after the date of parturition (39 days after condi-
tioning) for females in Group CP and Subgroup CP.

Testing procedure for nonpregnant females. Eemales in
Subgroup CP were given an opportunity to consume donor
placenta 25 days after reaching criterion in TAC (compara-
ble to the interval prior to the parturition test for Subgroup
CP) and again at 39 days after reaching criterion (compara-
ble to the interval between conditioning and the postpar-
tum test for Subgroup CP).

RESULTS

Taste Λ version Conditioning

The majority of animals receiving TAC (Subgroups CP
and CP) required 2 pairings of placenta with LiCEinduced
illness to reach criterion. The mean number of pairings-to-
criterion for each group is presented in Table I. Most
animals exhibited diarrhea and general inactivity following
the injection of LiCl, but no long-term effects such as
weight loss were noted. All females continued to show
ovarian cyclicity as verified by vaginal smears obtained
throughout the conditioning procedure.

Observations of Placentophagia at the First Parturition

The 2 measures of placentophagia (ingestion of delivered
placenta during parturition, and of donor placenta immedi-
ately after parturition) were combined to provide an
indication of the female’s response to placenta at parturi-
tion. To be scored as exhibiting an aversion to placenta at
parturition, an animal had to manifest both a decrement in
the consumption of her own placenta during parturition
and the absence of ingestion of donor placenta presented
immediately after parturition.

All the females that had been treated with LiCl unpaired
with placenta (Group CP) continued to exhibit placento-
phagia during, and immediately after, parturition. The
conditioned females (Subgroup CP) exhibited an aversion
to placenta at parturition: 6 of the 7 animals in Subgroup
CP showed a decrement in placentophagia during parturi-

TABLE I

DESIGN AND RESULTS OF EXPERIMENT I: TAC TO PLACENTA INDUCED IN NULLIPARAE
(PROPORTION OFGROUP EXHIBITING PLACENTOPHAGIA)

*AII animals determined to be placentophagcs in a pretest.

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