The Effect of Frequency of Ejaculation on the Semen Production, Seminal Characteristics, and Libido of Bulls during the First Post-Puberal Year

Abstract

Summary In a study using nine Holstein bulls, sexual interest was first expressed at an average age of 29.4 weeks. Ability to ejaculate was first demonstrated at an average of 38.9 weeks. Approximately 10 weeks was required for the transition from the infantile to the sexually functional bull. Highly significant differences were found in semen volume, per cent motile sperm, sperm concentration, total sperm per ejaculation and total motile sperm per ejaculation as the bulls aged during a 1-year period after puberty. No significant differences in semen volume, sperm concentration, per cent motile sperm, semen pH, total sperm per ejaculation, total motile sperm per ejaculation, or per cent atypical sperm were found attributable to frequency of ejaculation when frequencies of once, twice, and three times per week were compared. A highly significant reduction of libido, as measured by the proportion of failures to mount and ejaculate, was found in bulls scheduled to ejaculate three times per week. Ejaculation frequencies up to three times per week were not harmful to the seminal characteristics nor to spermatozoan production of young bulls except as they adversely affected libido.