The effect of mating female rats at 35 or 80 days of age on pup production and maternal weight

Abstract

2 groups of 10 rats each were mated for the 1st time at 35 days and 80 days respectively. At 106 days of age the early-mating group had produced 233 pups, whilst the other group had produced 99 pups. Pups produced from the early litters were not smaller than those produced later, but individual litters were smaller. The size of the litter increased with parity. The weight of dams in both groups was similar at 106 days of age.