Influence of ejaculation frequency on sperm characteristics, ionic composition and enzymatic activity of seminal plasma in rams

Abstract

Influence of frequency of ejaculation on the ionic composition and enzymatic activity of the seminal plasma and the spermatozoa parameters was evaluated. Semen was collected from 8 rams for a period of 12 days in four successive phases with a gradually increasing semen collection intensity. Each phase continued for 3 days and rams were ejaculated 1, 3, 6 and 8 times per day during phase I, II, III and IV, respectively. Semen volume, sperm concentration and progressive motility rates decreased significantly with regards to elevated semen collection frequency. Though abnormal sperm morphology increased, no specific type of sperm abnormality or localization, i.e. acrosome, head, mid-piece or tail, was noted in response to increased ejaculation frequency. Dead sperm rate fluctuated between 3.4 and 6.2% during the study. The highest daily sperm output was reached by 3–6 times of collection per day. However, further increase of the ejaculation frequency to 8 times or decrease to once a day reduced daily sperm output ( P<0.05). Seminal plasma sodium and potassium concentration increased significantly with regard to elevated semen collection intensity. In contrast, calcium and magnesium levels reduced markedly ( P<0.01) from phase I to IV. Although aspartate amino transferase (AAT) and glutamic–pyruvic transaminase (GPT) activity increased ( P<0.01) in the seminal plasma the lactate dehydrogenase (LDH) level dropped ( P<0.01) in the later phases of higher intensity semen collection. Semen collection frequency may influence ionic composition and enzymatic activity in the seminal plasma in addition to the spermatozoa parameters and daily sperm output in the ram.