Effects of age and parity on litter size and offspring sex ratio in golden hamsters (Mesocricetus auratus)

• Published in: Journal of reproduction & fertility Vol. 83; no. 1; pp. 209 - 214
• Main Authors: Huck, U W, Pratt, N C, Labov, J B, Lisk, R D
• Format: Journal Article
• Language: English
• Published: England Society for Reproduction and Fertility 01-05-1988
• Subjects: Aging - physiology; Animals; Cricetinae; Female; Litter Size; Mesocricetus; Parity; Sex Ratio; Weaning
• ISSN: 1470-1626; 0022-4251; 1741-7899
• DOI: 10.1530/jrf.0.0830209

Golden hamsters that were mated repeatedly from 55 days of age produced 6–12 litters. Litter size at birth rose between the
1st and 2nd litters, peaked on the 3rd, and declined steadily after the 5th litter. Offspring sex ratio (% male) at birth
followed a similar pattern: increasing between the 1st and 2nd litters, remaining high through the 3rd, and becoming increasingly
female-biased thereafter. Weaning success decreased sharply after the 6th litter and most dams failed to raise any young to
weaning after the 9th litter. These sequential effects on litter size, offspring sex ratio and weaning success were also observed
in females mated once at different ages, but they occurred considerably later in life, i.e. increasing parity hastened the
effects of advanced age. These ageand parity-related changes in litter composition are consistent with the Trivers–Willard
hypothesis that physiologically-stressed females would skew offspring sex ratios to favour daughters. However, since the observed
changes in sex ratio were probably due to differential prenatal mortality, their adaptive significance is unclear.
Keywords: age; parity; sex ratio; weaning success; golden hamsters; litter size