Breeding of Djungarian hamsters (Phodopus sungorus): influence of parity and litter size on weaning success and offspring sex ratio
1995
Lerchl, Alexander
The reproduction of 368 breeding pairs of Djungarian hamsters (Phodopus sungorus) has been recorded and evaluated during 5 consecutive years. Three-hundred-and-eight pairs (=83.7%) were successful breeders giving birth to 2113 litters (up to 13 per dam) with a total of 12,591 offspring (mean: 6.0α2.2 [αSD] per litter). One-hundred-and-fifty dams delivered within 25 days after pairing, indicating a breeding success in the first oestrous cycle of 40.8% of all pairs (95% confidence interval: 35.7%-46.0%). The average number of offspring was higher in the 2nd than in the first litter, reaching a maximum in the 3rd (6.8α2.0), and decreasing thereafter. The loss of offspring (mean: 24.2%) was higher in older parents and influenced by the number of offspring per litter, indicating that experience and stress contribute to breeding success. A small, but significantly higher number of females was recorded only when no loss of offspring occurred until weaning (females: 2.36α1.75; males: 2.16α1.63, P<0.001). There was no indication of a shift of the offspring sex ratio towards favouring females with increased litter numbers, in contrast to the predictions of the Trivers-Willard hypothesis, at least with respect to the species and the breeding conditions as described in this report. Since all breeders were kept under long-day type photoperiods (16L : 8D), no signs of seasonality in breeding outcome were noted.
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