Diagnosis and effects of urine contamination in cooled-extended stallion semen.

This research paper examines the effect of urine contamination in stallion semen and tests different methods to detect it. The study shows that urine affects sperm motility and can be determined through specific tests for urea and creatinine concentrations and a commercial test strip called Azostix.

Research Objectives and Process

• The study primarily aimed to gauge the impact of urine contamination on the sperm motility, both in fresh and cooled-stored stallion semen. Furthermore, it aimed to test the viability and accuracy of several methods to confirm the presence of urine in semen samples.
• The research was conducted using 37 ejaculates from 11 stallions with no prior history of urospermia (presence of urine in semen). The samples were divided into 5 ml aliquots and deliberately contaminated with urine for the study.
• The samples were then assessed for various parameters including sperm motility, color, odor, pH, creatinine concentrations, and urea nitrogen concentration. These tests occurred both before and after 24 hours of cooling.
• The research team used two methods to measure urea nitrogen concentration: a semiquantitative test strip (Azostix) and a quantitative automated analyzer. This allowed comparison between the two methods.

Research Findings

• Urine contamination led to a significant reduction in total and progressive motility in all analysed semen samples, both before and after cooling. The results indicated that the contamination led to a decrease in sperm motility and that the negative effects were not mitigated by cooling the samples.
• The concentrations of urea and creatinine in the semen (which are indicators of urine presence) were significantly different in urine-contaminated samples versus the control group with no contamination.
• An evaluation of the effectiveness of different detection techniques showed that:
  • Odor assessment had moderate sensitivity (65%) but was highly specific (100%), implying it only occasionally recognized contamination, but when it did, it was always correct.
  • Color assessment had low sensitivity (47%) and moderate specificity (79%), indicating it was often incorrect when identifying contamination.
  • Azostix strips demonstrated high sensitivity (95%) and specificity (97%), frequently correctly detected contamination.

Key Takeaways

• Urine contamination considerably impacts the motility of stallion sperm in both raw and cooled semen, and the degree of impairment is dependent on the concentration of urine present.
• The study demonstrates that standard practices of color, odor, and pH assessment to diagnose urine in stallion semen are not reliable methods alone.
• Measurements of urea and creatinine concentrations, along with Azostix strips test, are reliable methods to verify the presence of urine in the semen. Specifically, Azostix test strips can present an efficient point-of-care tool for diagnosing urine contamination in stallion semen.