Sperm motility of Prochilodus lineatus in relation to dilution rate and temperature of the activating medium

P>The objective of this study was to assess the effects of an activating solution on the sperm motility duration (SMD) of 'curimbata', Prochilodus lineatus through of the definition of qualitative and quantitative parameters of the semen pool used in the experiment; evaluation of the effects of different ratios of semen dilution corresponding to 1 : 1, 1 : 2, 1 : 20, 1 : 200, 1 : 2000, 1 : 20 000 and 1 : 100 000 semen:dilute solution on the SMD and, assessment of the effects of different temperatures of the activating solution (5, 10, 15, 20, 25, 30, 35, 40, 45 and 50 degrees C) on the SMD. The results of SMD were directly proportional to the dilution (P < 0.05), starting from the dilution of 1 : 2 (semen:water), with 23.04 s. Were used three replicates of the semen pool for each test. Two-year-old brookstock were maintained in ponds culture conditions. In November-December 2006, twelve mature males broodfish were selected (mean weight and length of 405.8 +/- 134.2 g and 25.6 +/- 3.1 cm, respectively). The males released that semen under slight pressure of the urogenital papilla were selected for the experiment. The SMD increased proportionally to the increase in dilution, until it reached a maximum of 28.83 s for the ratio 1 : 100 000 semen: dilute solution. The results of SMD in relation to the temperature of the activating solution exhibited a quadratic behavior (P < 0.05) with a maximum theoretical performance in terms of sperm motility duration of 21.36 s at a temperature of 17.3 degrees C. Thus, for the species considered, the increase in the dilution ratio proved favorable for the rise in motility duration until the maximum value studied of 1 : 100 000 semen:dilute solution. As for the temperature of the activating solution, the best results of SMD were obtained at the temperature of 17.3 degrees C. At higher temperatures used in the experiment (25, 30, 35, 40, 45 and 50 degrees C), a decrease in motility duration.