Effect of urine on semen quality in turbot (Psetta maxima)

The deleterious effects of urine contamination on the quality of spermatozoa were observed in turbot (Psetta maxima). In order to overcome this problem, two methods of sperm collection were compared to evaluate on urine contamination. When collected by stripping, the mean contamination rate of sperm by urine was 15.3% (urine volume: sperm volume). The catherization of ureter prior to sperm collection significantly decreased the urine contamination to 9.3%. The composition of urine was measured in starved and fed juvenile turbots during a 24-h period. Both urea concentrations and pH varied in relation with the diet and showed significant daily variations (P < 0.05). The concentration of urinary inorganic ions, the osmolality, and the glucose content were not influenced by the dietary status of fishes. Artificial urine contamination of milt induced a delay in the initiation of spermatozoa motility. Compared to control, sperm velocity of 30% urine contaminated samples was significantly decreased from 230 mu m s(-1) to 160 mu m s(-1) when measured at 10-s post-activation(P < 0.05). The addition of 10% urine in sperm samples for a 15 min incubation time significantly decreased the percentage of motile cell at 10-s post-activation from 83.4 to 54.2%. Furthermore, the deleterious effect of urine contamination on motility parameters were marked with the incubation time. The endogenous ATP stores showed 32.4% decrease in sperm contaminated by 10% (v/v) urine. Short-term storage and fertilization capabilities of urine contaminated sperm samples were also lowered. Nevertheless, the short-term storage capacity could be improved by diluting sperm in an artificial seminal plasma. In practice, urine contamination of turbot sperm samples must be absolutely prevented by previously emptying the urinary bladder. (C) 1998 Elsevier Science B.V. All rights reserved.