Tama Zoo 's female Chimpanzee, "Mil" (21 years old), has been confirmed to be pregnant through artificial insemination. This marks the fourth successful artificial insemination in the park's efforts, which began in 2016. This article introduces the efforts made with Mil. For information on past artificial insemination attempts, background, and methods, please see "The Road to Success in Chimpanzee Artificial Insemination."


Chimpanzee "Mill"
Mill is the fourth individual to be selected. The selection criteria, as with previous individuals, was based on the "kinship occupancy rate" value in the domestic pedigree registry (from Japanese Association of Zoos and Aquariums Aquariums website). Pedigree registration and breeding plan The male is named "Decky" (estimated to be 45 years old). Although Decky possesses valuable genes of wild origin, he is unable to mate, so we are working to ensure he reproduces through artificial insemination and contribute to maintaining the genetic diversity of Chimpanzee kept in captivity in Japan.

Our efforts with the mill began in 2022. The method is: The same method used to successfully raise "Mikan" (female, 18 years old) two years ago. This was done. One of the important points in artificial insemination is the timing of the procedure. When Chimpanzee go into estrus, a part of their rear end called the sexual skin swells up like a balloon, so the degree of swelling is checked visually. However, since visual inspection alone is insufficient, human ovulation test strips are also used to estimate the ovulation period more accurately.

However, in Miru's case, the period of ovulation was inconsistent, sometimes long and sometimes short, making it difficult to determine the optimal timing for artificial insemination. Therefore, instead of making the decision alone, we decided to discuss it with multiple people before deciding on the date. In addition, to time the procedure as close to the ovulation period as possible, we increased the frequency of using ovulation test strips and also measured hormone levels in the blood through blood tests.

As a result, I underwent a total of six artificial insemination procedures in 2022 and 2023, and became pregnant twice. Unfortunately, the first attempt ended in a miscarriage, but this time the pregnancy is progressing well.

Mil loves children and takes good care of them on a regular basis. I'm sure she will raise her own child with great love. First and foremost, we will do our best to ensure Mil has a safe delivery by managing her health and creating a stress-free environment.

[Sato, Animal Care and Exhibition Staff, North Tama Zoo]

◎Related News
・ We're looking for names for Sazae-san's baby! (January 24, 2003)
・ Sazae-san's baby is named "Miru"! (February 28, 2003)
・ Chimpanzee "Mil" gives birth for the first time (May 24, 2013)
・ Thank you, Sazae Chimpanzee. (July 7, 2017)
・ Sperm preservation and artificial insemination efforts: From Wildlife Conservatio Center Laboratory (December 13, 2019)
・ Progress made! Efforts toward semen cryopreservation. (March 11, 2022)
・ Chimpanzee has been born! (June 14, 2022)
・ Chimpanzee "Mikan" gives birth for the first time (July 4, 2022)

(December 15, 2023)