Analysis of Sexual Behavior in Rams (Ovis aries)

Abstract

In this study, a matured ram was paired with an estrus ewe and sexual behavior was investigated. All the behavior was recorded by a time-lapse video tape recorder from the start of pairing. The series of unit movements comprising the sexual behavior, the mounting series (MS), was extracted from the record and analyzed quantitatively (n=774). The MS starts from ram's approaching or following a ewe and ends by ram’s mounting on a ewe. The sexual behavior was consisted of the following eight unit movements, following or approaching (F/A), chin resting (CR), flehmen (Fl), mounting (Mo), nosing (No), nudging (Nu), pushing (Pu) and twisting (Tw). Analysis of a frequency of any combinations of two unit movements consisted of preceding and succeeding ones, observed in the MS was conducted by cell-by-cell test using the transitional matrix to make a flow-diagram of the ram's sexual behavior. As a result, the pattern of unit movements, F/A-Tw-Nu-CR-Mo, formed a main route of the MS, whereas the repertoire of a sequential pattern increased by diverging. Though Fl and No didn’t lead to mounting directly, these movements associated with olfactory perception also belonged to sexual behavior and may have independent function from other six unit movements that constitute the MS.