(Physical, chemical and microscopic seminal characteristic of Rhamdia hilarii (Valenciennes, 1840) in field conditions.)

Abstract

Aiming to verify the seminal characteristics and indirect method of sperm evaluation of "bagre", Rhamdia hilarii (Valenciennes, 1840), in field condition, the spermatic material from 29 individuaIs from the Jaguari River near Jaguariúna city (São Paulo) was collected during the reproductive season from September to December 1981. The seminal characteristics examined and values obtained when estimated by confidence interval of 95% were: semen volume, 0.57 to 1.3 ml; subjective motility, 78.16% to 85.64%; spermatic concentration, 59,222,106 to 67,843,412 per mm³ and percentage of live spermatozoa by differential staining method, 83.82% to 89.64%. The correlation coefficient between the spermatocrit and concentration was found to be r= 0.75* and was statistically significant at the 5% leveI of probability. The regression equation was: Y = -6.531+1,460.095 X, where Y represents the spermatozoa concentration per mm³ and X, the spermatocrit per milimeter. The methylene-blue reduction test showed no correlation of the time of methylene-blue discoloration with the spermatic concentration.