Factors affecting the presence of reactive oxygen species in the fresh and extended porcine ejaculate.

摘要

Experiment 1 examined changes in ejaculate characteristics, semen quality and membrane lipid peroxidation over time in boars maintained under a 3 times or 1 time per week collection frequency and determined the effects of semen extender and storage time on semen quality and sperm membrane lipid peroxidation. In general, extender and storage time affected sperm quality. Sperm stored in a commercially available 3-day extender were lower for sperm quality and higher for lipid peroxidation after 7 days of storage post-collection compared to a commercially available 5-day extender.;Experiment 2 used density gradient centrifugation to separate extended boar sperm into sub-populations for analysis of sperm quality, plasma membrane lipid peroxidation and sperm cell fatty acid composition over a 7 day storage period post-collection. Three ejaculates were collected and analyzed following exposure to three consecutive collection periods. The first ejaculate was collected from boars that had previously been maintained on a 1 time per week frequency. The second ejaculate was collected following a period of five collections in four days (fifth collection analyzed). The third ejaculate was a collected after a period of three days of rest following the collection of the second ejaculate. Collection period affected sperm motility over the storage period post-collection. Collection period, density layer and day of storage post-collection affected the separation patterns of sperm cells using density gradient centrifugation. These results suggest that changes in sperm separation seem to be primarily affected by collection period and day of storage post-collection and to a lesser extent, sperm motility, but not plasma membrane lipid peroxidation.;Experiment 3 evaluated the effect of dietary selenium on sperm production and sperm quality. The dietary treatments were a non-supplemented negative control basal diet or the basal diet supplemented at 0.3 ppm with either organic selenium or inorganic selenium. A secondary objective was to examine changes in sperm quality over a six day storage period post-collection. Boars were fed the dietary treatments beginning at the time of weaning. Dietary treatment affected the level of selenium in the blood plasma but not the semen. Dietary treatment did not affect volume, concentration or total sperm in the ejaculate, nor did dietary treatment affect sperm motility, progressive motility, morphology, membrane lipid peroxidation and glutathione peroxidase activity over the 6 day storage period postcollection.;Following density gradient centrifugation, sperm motility, progressive motility, morphology and the percentage of sperm recovered were higher in the 90% gradient compared to the 45% gradient on day 1 but not day 6 of storage post-collection. These results indicate that dietary treatment affected selenium levels in the blood, but did not affect sperm production or quality. Boar sperm cells decrease in progressive motility and buoyant density over a six day storage period which appears to affect the sperm motility, progressive motility, morphology and the percentage of sperm recovered in the high and low density layers following density gradient centrifugation, however these changes do not appear to be affected by lipid peroxidation.