Effect of Month and Stallion on Seminal Characteristics and Sexual Behavior

Abstract

Eight seminal and three behavioral characteristics were measured during and immediately following collection of first and second ejaculates of semen from each of five stallions over a 12-month period. The number of paired ejaculates per criterion ranged from 165 to 173. The parameters studied were: volume of gel-free semen, sperm concentration per milliliter, total sperm per ejaculate, motility in raw and diluted semen, degree of clumping, pH, freezing-point depression, number of mounts per ejaculate, reaction time and copulation time. A highly significant difference (P<.01) among months was found for all measurements on first ejaculates except sperm concentration per ml, pH, freezing-point depression of seminal plasma and copulation time. Sperm concentration per ml and freezing-point depression were significant at the 5% level of probability. Variation due to stallion was significant (P<.01) for all characteristics of first ejaculates except motility, freezing-point depression and copulation time, and freezing-point depression was different at the 5% level of probability. The trends were similar for second ejaculates, with respect to the influence of month and stallion (table 1). Differences (P<.01) between the means of first and second ejaculates were observed for all criteria except semen volume, motility, freezing-point depression and copulation time.