Kai O, Sakemi K, Suzuki Y, Sonoda Y, Imai K
Laboratory of Animal Reproduction, College of Agriculture and Veterinary Medicine, Nihon University, Fujisawa, Japan.
Exp Anim. 1995 Oct;44(4):307-13. doi: 10.1538/expanim.44.307.
Effects of age at first-pairing on the reproductive performance of the gerbil were studied throughout the reproductive life. Six groups of 7-30 female gerbils were paired monogamously with males at different ages. Out of 101 pairs in 6 groups, 79 (78.2%) produced 1 or more litters. The mean litter size at birth and mean weaning rate of 846 litters were 4.4 (totally 3,733 pups) and 67.4% (2,517 pups), respectively. Reproduction was compared in the 6 age groups. The littering rate (No. of females with litters/No. of female paired) was significantly lower in two groups in which mature females were paired with age-matched males (Group 4) or the oldest females with younger, sexually mature males (Group 6). The interval from pairing to the first litter was shortest in two groups in which mature females were paired with one month older, sexually mature males (Groups 3 and 5). Although the oldest pairs (Group 6) produced about 7 litters, the pairs from the other 5 groups produced about 10 or more litters throughout their reproductive life. The weaning rate was significantly higher in Group 6 (the oldest pairs) than in the younger groups. The effects of parity on reproduction were estimated from the data for the 61 pairs which produced more than 8 litters in the 6 groups. The number of pups at birth and the weaning rate were decreased in last 20-30% of the total parity in all 6 groups, although the age at the last litter in all groups was significantly different. The data suggest that any decline in reproduction may be due to not age but parity in the Mongolian gerbil.
在整个生殖期研究了首次配对年龄对沙鼠生殖性能的影响。将六组7至30只雌性沙鼠分别与不同年龄的雄性沙鼠进行一夫一妻制配对。六组中的101对沙鼠中，79对（78.2%）产下一窝或更多窝幼崽。846窝幼崽的平均出生窝仔数和平均断奶率分别为4.4只（共3733只幼崽）和67.4%（2517只幼崽）。对六个年龄组的繁殖情况进行了比较。在两组中，即成熟雌性与年龄匹配的雄性配对（第4组）或最年长雌性与年轻的性成熟雄性配对（第6组），产仔率（产仔雌性数量/配对雌性数量）显著较低。在两组中，即成熟雌性与大一个月的性成熟雄性配对（第3组和第5组），从配对到第一窝产仔的间隔最短。虽然最年长的配对组（第6组）产仔约7窝，但其他五组的配对在其整个生殖期产仔约10窝或更多。第6组（最年长的配对组）的断奶率显著高于较年轻的组。根据六组中61对产仔超过8窝的数据估算了胎次对繁殖的影响。在所有六组中，总胎次的最后20 - 30%出生的幼崽数量和断奶率均下降，尽管所有组最后一窝产仔时的年龄有显著差异。数据表明，在长爪沙鼠中，繁殖能力的任何下降可能是由于胎次而非年龄。
