PSX-42 Characterization of the effects of high selenium feed on spermatogenesis in rams

Abstract

Abstract Selenium (Se) is an essential element that is required by animals to maximize health and production. Some western rangelands contain alkaline soils that are naturally high in Se while others have been contaminated with elevated concentrations of bioavailable Se. Anecdotal evidence of poor reproductive efficiency has been reported on some seleniferous ranges. In order to determine the effects of high Se feeds on spermatogenesis, mature rams were fed alfalfa pellets containing 0.1, 7.5, 15, or 25 ppm Se. Desired Se concentrations were achieved by mixing western aster containing approximately 3,000 ppm Se with alfalfa. Pellets were fed at 3% of body weight for twelve weeks during the breeding season. Semen and blood samples were collected weekly and semen viability, motility, and morphology were evaluated. After twelve weeks of being fed high Se pellets, one testicle from each ram was surgically removed for morphometric and histological evaluation. The rams were then fed a control alfalfa pellet during an eight week recovery period while monitoring and collection of samples continued. At the conclusion of the recovery period the second testicle was surgically removed for analysis. None of the rams demonstrated any visible clinical signs of chronic Se poisoning during the study. Rams fed the high Se-containing alfalfa pellet had a decrease in sperm motility and an increase in the percentage of abnormal sperm. Within several weeks of beginning the recovery period, the negative side effects were reversed. Initial histological surveys suggest minimal histologic changes. This is supported by the rapid recovery of spermatic motility which suggests a maturation defect and not a change in spermatogenesis. These findings indicate that in sheep, subclinical Se intoxication does cause significant male reproductive damage. More work is needed to better characterize this damage and to determine its effect on fertility and production.