Effect of repeated semen ejaculation on sperm quality and selected biochemical markers of canine semen

The aim of this study was to evaluate the quality parameters and selected biochemical markers of canine semen sampled at 24-h intervals over a period of 5 days, preceded by 6 months of sexual abstinence. Full ejaculates were obtained from 6 dogs. Ejaculate volume and total sperm counts in the ejaculate decreased gradually on successive sampling days. The percentage of total motile spermatozoa (TMOT), percentage of progressively motile spermatozoa (PMOT), sperm plasma membrane integrity (SPMI), and sperm mitochondrial membrane potential (MMP) increased on successive days of sampling. In addition, ATP content increased in spermatozoa. Total protein content (TPC) and the activity of aspartate aminotransferase (AAT), alkaline phosphatase (AP), and acid phosphatase (AcP) decreased in seminal plasma. Repeated ejaculation over a period of 5 days induced changes in the qualitative and quantitative parameters of canine semen. A decrease in the values of some biochemical markers of semen, secreted by the epididymis and the prostate gland, could point to disturbances in the secretory activity of these organs. Canine semen sampled after prolonged sexual abstinence is generally characterized by less desirable quality parameters, and this observation should be taken into consideration when semen is collected for artificial insemination or preservation. Semen quality can be significantly improved by repeating the sampling procedure after 24 hours. On the other hand, repeated sampling on successive days can significantly decrease total sperm counts in the ejaculate. As a result, a sufficient number of semen doses for artificial insemination may not be obtained from a single ejaculate.