1. Signs of estrus

We classify estrus into three stages: early, mid, and peak, and collect information on estrus signs and behavior for each item. (Table 1) Estrus stage classification of males and females was conducted for 10 cases that came into estrus and mated between February and June in the period 2001-2020 (Table 2). The first day of mating is set as day 0, and the date (mean ± standard deviation) of onset of each symptom is shown retroactively. The timing of mid- and peak estrus is synchronous between males and females, but the onset of early estrus is around one month for females, whereas it begins two to three months earlier for males.

• 表1.発情ステージ 分類

  estrus stage		発情兆候・行動
  メス	first term (e.g. of pregnancy)	マーキング、水浴、陰部レベル１
  	mid-stationary period	恋鳴き、オスへの興味、陰部レベル２
  		膣粘細胞角化細胞増加 発情ホルモン上昇
  	peak of estrus	陰部レベル３、発情ホルモンピークから下降
  		プレゼンティング⇒交尾
  male (animal)	first term (e.g. of pregnancy)	マーキング、水浴
  	mid-stationary period	恋鳴き、メスへの興味
  	peak of estrus	メスへの強い興味、マスターベーション⇒交尾

• 表2.発情ステージ 発現時期

  	first term (e.g. of pregnancy)	mid-stationary period	peak of estrus
  メス	-20.0±12.2 days	7.6±1.4 days	0.6±0.8 days
  male (animal)	2~3 months	6.3±2.0 days	2.4±1.9 days

  ※交尾初日を0日とする　n=7

語句説明及び補足

• 陰部レベル ・・・・色調や腫脹により1～3にランク付け
• 恋鳴き・・・・・・発情期特有の鳴き声
• 膣粘膜細胞・・・・当パークの場合尿中に排泄された細胞をパパニコロウ染色をして青色有核細胞、赤色有核細胞、無核細胞に分類カウント
• 発情ホルモン・・・当パークの場合は、尿中エストロジェン代謝産物の一つであるエストロンｰ3ｰグルクロニド（Estron-3-Glucuronide,E1G）を測定

2. Determining the right time for mating

To summarize the estrus signs and E₁G of "Ryohama" in 2020 (Figure 1), an increase in E₁G, an increase in the frequency of love cries, and swelling and redness of the pubic region were observed toward the peak of estrus. Eventually, they cohabitated and mated after mutual purring and presenting, in which the female turned her buttocks toward the male and raised her tail, was observed. Babara et al. (2003) collected cells from vaginal swabs and classified them by Papanicolaou staining as "nucleophilic", "nucleophilic", and "anucleolipid". cells" by Papanicolaou staining. The Park has reported that the percentage of basophilic cells crosses with acidophilic cells approximately one week before mating, and that the percentage of keratinocytes exceeds that of other cells two to three days before mating, indicating that this method is effective in predicting the optimal time for mating in advance. To reduce the burden on individuals, the Park does not collect vaginal mucosa cells directly from the vagina, but rather observes them from exfoliated cells of the vaginal mucosa excreted in urine. The variation of vaginal mucosa cells in Ryohama (Figure 2) showed a predominance of acidophilic cells and keratinocytes 6 and 2 days before mating, respectively, and similar results were obtained from exfoliated cells excreted in the urine.

尿中に排出された膣粘膜剥離細胞（パパニコロウ染色）

• 

  発情中期 （有核好塩基性細胞と有核好酸性細胞）

• 

  発情ピーク （無核角化細胞優位）

Figure 1: Signs of estrus and urinary E₁G (Ryohama, 2020)

図2.尿中膣粘膜細胞及びE₁Gの推移（2020年 良浜）

3. breeding results

In order to give first priority to natural mating, we aimed to synchronize the estrus of males and females and had them frequently exchange exercise areas and smell their feces and markings during winter and spring. As a result, 14 cases of mating were approved between 2001 and 2020. Out of the 14 cases, 11 were litters, and the conception rate was 78.6%, which is high. In recent years, the aging of breeding individuals has become an issue. In the case of the male "Eimei," since 2016 (age 24), in order to preserve his stamina during mating, we have been trying to minimize the time he sees the female over the cage and to give him time to rest by leaving at least 7 hours between mating.

アドベンチャーワールドにおける繁殖成績