东方田鼠室内繁殖与生长发育观察

目的　探寻室内东方田鼠的繁殖与生长发育规律。方法　以F4代鼠及其仔代(F5)为对象，分别观察其繁殖与生长发育情况。结果　室内东方田鼠一年四季均具有繁殖能力，春(3～4月)秋(10～11月)两季为繁殖高峰期；雌雄单一配对比多性比配对的母鼠繁殖率明显提高；母鼠怀孕期20～21d，窝产仔数3～11只，平均(4.8±1.5)只，初生重2.5～4.4g；幼鼠3　d龄耳壳全部竖立，6～8d龄被毛长全，7～11d龄开眼，10～11d牙齿长齐；15d龄左右具有采食能力，20d龄可完全断奶；60～70d龄可见个别雌鼠阴门开孔，75～90d龄可见多数雌鼠阴门开孔和雄鼠睾丸明显下位；3月龄后体重、身长增长不显著。结论　开放式(普通级)饲养环境下，室内东方田鼠的繁殖季节、窝产仔数及初生重与野生东方田鼠基本相似；种群密度、性比对雌鼠的繁殖率有明显影响；2～3月龄为性成熟期，3～4月龄为体成熟和初配时期。但成熟时间存在个体差异，同时受饲料营养和环境因素的影响。

Laboratory Observation onBreeding and Growth and Development of Microtus fortis

Objective To find out the bree ding， growth and developmentcharacteristics of Microtus fortis[ H T5”SS in laboratory.Methods Laboratory o bservations were carried out on the fourth and fifth filial generation (F4 & F 5).Results The females bred all the year with the major seasons from March to April and from Oc tober to November. The breeding rate for single sex ratio mating was much highe r than that for multi-sex ratio mating. The pregnant period was 20-21 days. The nest size was ranged from 3 to 11 with the mean size of 4.8±1.5. The wei ght of newborn M. fortis was 2.5-4.4 g， Ear erectio n occurred among 3-day-old infant M. fortis. Hair cover was fully-grown at the age of 6-8 days. Eyes opened at 7-11 days old. All teeth emerged at 10-11 days old. Young M. fortis could feed th emselves at the 15th day after birth and live completely independently at the 20 th day when breast-feeding could be stopped. A few of female pudenda holes coul d be seen at 60-70 days old， and most of female pudenda ones and apparent male t entes seen at 75-90 days old. The growth of body weight and height weren't rema rkable after 3 months from birth.Conclusion Under the open indoor environment， the breeding season， nest size and weight o f newborn of M. fortis in laboratory were as that of w ild M. fortis.The densi ty and sex ratio of colony showed an apparent influence on breeding rate of f emales. Most of M. fortis matured completely at the s econd to 3rd month after birth and could make the first mating at the 3rd-4th month. But there existed i ndividual difference in maturing period， which was influenced by nutrition and environmental factors.