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

The deleterious effects of urine contamination on the quality of spermatozo a were observed in turbot (Psetta maxima). In order to overcome this proble m, two methods of sperm collection were compared to evaluate on urine conta mination. When collected by stripping, the mean contamination rate of sperm by urine was 15.3% (urine volume: sperm volume). The catherization of uret er prior to sperm collection significantly decreased the urine contaminatio n to 9.3%. The composition of urine was measured in starved and fed juvenil e turbots during a 24-h period. Both urea concentrations and pH varied in r elation with the diet and showed significant daily variations (P < 0.05). T he concentration of urinary inorganic ions, the osmolality, and the glucose content were not influenced by the dietary status of fishes. Artificial ur ine contamination of milt induced a delay in the initiation of spermatozoa motility. Compared to control, sperm velocity of 30% urine contaminated sam ples 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 s perm samples for a 15 min incubation time significantly decreased the perce ntage of motile cell at 10-s post-activation from 83.4 to 54.2%. Furthermor e, the deleterious effect of urine contamination on motility parameters wer e marked with the incubation time. The endogenous ATP stores showed 32.4% d ecrease in sperm contaminated by 10% (v/v) urine. Short-term storage and fe rtilization capabilities of urine contaminated sperm samples were also lowe red. Nevertheless, the short-term storage capacity could be improved by dil uting sperm in an artificial seminal plasma. In practice, urine contaminati on of turbot sperm samples must be absolutely prevented by previously empty ing the urinary bladder. (C) 1998 Elsevier Science B.V. All rights reserved .