In uniparental Phodopus sungorus, new mothers, and fathers present during the birth of their offspring, are the only hamsters that readily consume fresh placenta

Abstract

Placentophagia is common among parturient female mammals but non-parturient females generally refuse placenta. Biparental male dwarf hamsters (Phodopus campbelli) readily consume placenta. The present study quantified placentophagia and liver acceptance in the closely related Siberian hamster P. sungorus in which males do not participate in the birth and are not responsive to a displaced pup. Sexually naïve P. sungorus males and females refused both placenta and liver (all groups <10%). Reproductive females specifically consumed placenta on the day before (G17), and the day of, parturition (G18) (>80%). Males rejected both tissues on G17 and accepted placenta soon after the birth (G18) (80%) only if they were present during the birth. Palatability of the placenta was not responsible for the species difference as P. campbelli accepted P. sungorus placenta. Results are consistent with a neophobic reaction to both placenta (conspecific or heterospecific) and liver as P. sungorus also rejected P. campbelli placenta.

Differences in placentophagia in relation to reproductive status in the california mouse (Peromyscus californicus)

“…In contrast to findings in rats (Kristal et al, 1981), rabbits (Melo & González-Mariscal, 2003), dwarf hamsters (Gregg & Wynne-Edwards, 2005) and Djungarian hamsters (Gregg & Wynne-Edwards, 2006), however, our results indicate that pregnancy alone does not increase placentophagia in female California mice. Among males, the prevalence of placentophagia was higher in expectant first-time fathers and in experienced fathers than in virgins, similar to findings in the biparental dwarf hamster (Gregg & Wynne-Edwards, 2005).…”

“…In summary, our results show that the pattern of placentophagia in female California mice is similar to that in female rats (Kristal, 1980) and rabbits (Melo & González-Mariscal, 2003) in that females tended to increase their attraction to placenta with maternal experience. In contrast to findings in rats ), rabbits (Melo & González-Mariscal, 2003), dwarf hamsters (Gregg & Wynne-Edwards, 2005) and Djungarian hamsters (Gregg & Wynne-Edwards, 2006), however, our results indicate that pregnancy alone does not increase placentophagia in female California mice. Among males, the prevalence of placentophagia was higher in expectant firsttime fathers and in experienced fathers than in virgins, similar to findings in the biparental dwarf hamster (Gregg & Wynne-Edwards, 2005).…”

“…To determine if mice show changes in their attraction to placenta specifically or to highly vascularized tissues in general, we also presented animals with liver in a similar manner (Gregg & Wynne-Edwards, 2005, 2006; Melo & González-Mariscal, 2003). Consistent with the hypothesis that placentophagia facilitates the onset of parental behavior in both sexes (Gregg & Wynne-Edwards, 2005, 2006; Jones & Wynne-Edwards, 2000), we predicted that both males and females would show increased likelihood of ingesting placenta with pregnancy (of their mates in the case of males), and would show further increases in placentophagia with birthing and/or parental experience. Additionally, we predicted that the prevalence of liver ingestion would not differ between the sexes or among reproductive conditions; we argue that although California mice mostly eat seeds (Merritt, 1974; Meserve, 1976), they are potentially likely to eat meat if the opportunity arises (pers.…”

Behavioral and endocrine consequences of placentophagia in male California mice (Peromyscus californicus)

“…Specifically, females' response to placenta changes from aversion when they are sexually inexperienced to attraction during late pregnancy or with birthing experience [18,20]. This behavioral transition has been reported in rats (Rattus norvegicus; [18]), house mice (Mus musculus; [18]), California mice (Peromyscus californicus; [27]), Siberian hamsters (Phodopus sungorus; [9]), Djungarian hamsters (P. campbelli; [8,9]), rabbits (Oryctolagus cuniculus L.; [25]), and sheep (Ovis aries) [23].…”

Placentophagia in weanling female laboratory rats

“…This might reflect a species difference related to the biparental social structure in P. campbelli , such that all of its members are highly disposed to exhibit placentophagia even outside the natal nest. In support, juveniles of the uniparental P. sungorus are less likely to completely consume placentae in a novel testing chamber than when in the natal nest with their parturient mother present (Gregg & Wynne‐Edwards, ). It is important to note that the Phodopus juveniles studied by Gregg and Wynne‐Edwards (, ) were not given a choice of novel substances to ingest, unlike our rats given liver and cake frosting at the same time as placenta, and this may have divided our weanlings' attention among multiple attractive stimuli and perhaps contributed to the apparent species differences the appetite for placenta.…”