Growth and Reproduction of the Chinchilla-Age at Vaginal Opening, Oestrous Cycle, Gestation Period, Litter Size, Sex Ratio, and Diseases Frequently Encountered

KUROIWA Junichi, IMAMICHI Tomonori

doi:10.1538/expanim1957.26.3_213

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Other Title

チンチラの発育と繁殖初回膣開口日令・性周期・妊娠期間・性比・飼育中頻発する疾病
チンチラの発育と繁殖--初回腟開口日令・性周期・妊娠期間・性比・飼育中頻発する疾病
チンチラノハツイクトハンショクショカイチツカイコウニチレイセイシ

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The paper deals with observations on growth and reproduction of the chinchilla in recent 4 years started from 1966 at this laboratory. There were large variations in age of vaginal opening (less than 71 days-308 days) with an average of 173.2±57.6 days in 45 females. The average length of 100 oestrus cycles in 24 females was 35.7±7.9 (15-62) days. The mean period of 5 gestations in 5 females was 110.4 (108-112) days. Eighty-one out of 123 litters were born between March and August during 3 years, and parturition never occurs in December. The most suitable season for reproduction of chinchillas may be from January to April, and a summer anoestrous seems to be present in August to early September as reported by Weir. The litter size ranged from 1 to 4 with a mode of 2 (46.3%) and an average of 1.90±0.76. More male kids were produced at birth at this laboratory, and sex ratio was 133.7 (98 females and 131 males) . In 1973, 37 chinchillas gave birth to 71 kids with an average litter size of 1.92, and 59 of them were successfully weaned (1.59 per litter) . Of these kids, 50 (1.35 per litter) attained 240 days of age (adulthood) . Among 91 subjected to investigation for causes of death, 23 (25.3%) were dead during newborn period, and 9 and 5 adults were dead of malocclusion (9.9%) and the prolapse of rectum respectively.

Journal

EXPERIMENTAL ANIMALS

EXPERIMENTAL ANIMALS 26 (3), 213-222, 1977

Japanese Association for Laboratory Animal Science

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