Necessity of exact examination of sperm characteristics to assess artificial insemination-subfertile bulls

Abstract

Conception rates of artificial insemination (Al) have gradually been decreasing in the cattle. In order to overcome this problem, Al centers need supply high-quality frozen semen whose insemination makes cow pregnant efficiently. Semen quality is conventionally assessed under the light microscope with cell biological methods, and only high-quality frozen semen straws are used for Al. However, lower conception rates are occasionally recorded in Al with frozen semen straws from some bulls (Al-subfertile bulls). In this paper, we introduce new methods to assess sperm molecular characteristics to find Al-subfertile bulls. (J. Reprod. Dev. 66:199-203, 2020)