| Abstract: | Investigated the initiation of pregnancy and the physiological significance of long intromissions (10–30 sec of intravaginal thrusting), in 4 experiments with 425 virgin and 808 multiparous female LVG golden hamsters and 102 stud males. Results show that virgin females required significantly less copulatory stimulation to induce pregnancy and maximize litter size. Ss receiving only long intromissions showed a 100% pseudopregnancy rate, suggesting that long intromissions can initiate the neuroendocrine response necessary to maintain pregnancy. When the male delivered only 1 or a few ejaculations, the inclusion of long intromissions significantly increased the percentage of both virgin and multiparous females that became pregnant. Order of ejaculations did not affect the proportion of multiparous females that delivered litters. However, litter size of females receiving the 1st or 5th ejaculation was significantly larger than that of females receiving the 10th or 15th ejaculation. Multiple-male matings did not augment pregnancy rates or litter sizes compared with matings with a single, rested male. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) |
