Canonical correlation analysis to identify the semen characteristics used to forecast the freeze survival of Curimba (Prochilodus lineatus) spermatozoa.

　　OBJECTIVE: To identify which sperm characteristics were able to predict more accurately the quality of curimba (Prochilodus lineatus) semen upon freezing using canonical correlation analysis.

METHODS: Eleven fish breeders with initial mean weight of 705.21 ± 111 g were used. For cryopreservation, 200 µL of semen were taken from each animal and diluted in the cryoprotectant solution (10% dimethyl sulfoxide and 5% Beltsville Thawing Solution Minitub) in a 1:4 ratio and placed into 0.5-mL straws. Sperm characteristics (motility, sperm abnormalities, total antioxidant activity and lipid peroxidation) were evaluated. A randomized block design with duplicate samples per treatment (fresh and frozen semen) was used. The block factor was the animals, and the experimental unit the ejaculates. Canonical correlation was used to evaluate the association between sperm characteristics of fresh semen and thawed semen.

RESULT: There was a significant association (P = 0.10) among the variables measured in fresh semen with the variables measured in thawed semen, and 78.6% of the difference observed in the thawed semen can be attributed to variation of variables measured in fresh semen. Sperm motility, motility duration and antioxidant activity of the thawed semen showed an inverse relationship with those of the fresh semen; whereas the minor sperm abnormalities, major sperm abnormalities and lipid peroxidation showed a direct relationship with those of the fresh semen. Only the rate and motility duration of the thawed semen presented high correlation (-0.63 and -0.73, respectively) with the canonical variable represented by the sperm characteristics of fresh semen.

CONCLUSIONS: The rate and motility duration of fresh semen may be used to predict the quality of the thawed sperm in Prochilodus lineatus.