title: Variation in fecal testosterone hormone concentration with season and harem size in Misaki feral horses.
abstract: On Misaki peninsula, Japan, fecal samples were collected from 14 Misaki stallions at monthly intervals for 12 consecutive months. The fecal testosterone concentration was measured by radioimmunoassay. We examined monthly fecal testosterone hormone patterns and the relationship between fecal testosterone concentration and breeding season and later harem size. Marked monthly variations in fecal testosterone concentration were observed. The fecal testosterone concentration began rising in March; the highest mean monthly concentration, 2.87 +/- 0.18 ng/g, was found in April, and the level remained elevated until the end of August and thereafter decreased. A significant correlation was found between the fecal testosterone concentrations and harem size in both the breeding and non-breeding season among the 14 stallions. It is therefore possible that the testosterone levels in feces, instead of blood, correlate very well with harem size in Misaki stallions. Our findings emphasized that the fecal testosterone concentration can be a powerful indicator for monitoring of endocrine status in wild stallions.
authors.affiliation: Department of Animal Hygiene, Zoonoses and Animal Behavior, Suez Canal University, Ismailia, Egypt. akhalil42@yahoo.com
authors.forename: Ashraf M
authors.initials: AM
authors.lastname: Khalil
authors.forename: Keiko
authors.initials: K
authors.lastname: Nakahara
authors.forename: Mikihiko
authors.initials: M
authors.lastname: Tokuriki
authors.forename: Yujiro
authors.initials: Y
authors.lastname: Kaseda
authors.forename: Noboru
authors.initials: N
authors.lastname: Murakami
mesh_terms: D000818:Animals; D000835:Animals, Wild / Q000502:physiology; D001947:Breeding / Q000706:statistics & numerical data; D005243:Feces / Q000737:chemistry*; D012739:Gonadal Steroid Hormones / Q000502:physiology; D006736:Horses / Q000502:physiology*; D007564:Japan; D008297:Male; D012621:Seasons; D012726:Sexual Behavior, Animal / Q000502:physiology*; D013739:Testosterone / Q000032:analysis* / Q000097:blood
chemical_list: D012739:Gonadal Steroid Hormones; D013739:Testosterone