Reproduction Abstracts

Introduction: Frozen and thawed ovine semen undergo morphological and functional changes that prevent or decrease the efficiency of fertilization. Sperm selection methods seek to improve the quality and viability of the fertilizing materials.

Material and methods: Four sperm selection methods by centrifugation were employed, using two silica colloidal solutions coated with silane (Ovipure™– Nidacom, Gothenburg, Swedis) or by polyvinylpyrrolidone 45% and 90% (Percoll – Nutricell, Campinas, Brazil), and varying the volume of colloidal solution (4 or 1 ml). Sperm total motility (TM) were evaluated by means±S.E.M. of CASA. In order to measure the integrity of the plasmatic and acrosomal membrane (integrity), an association of probes FIT-PSA/IP were used.

Results and discussion: Sperm samples TM before selection on 4 and 1 ml protocols were 27.0±3.1% and 24.3±1.9%, integrity were 19.9±2.1% and 27.1±1.6%. Protocols using silica colloidal-silane showed higher (P<0.05) TM (4 ml: 62.0±4.1%; 1 ml: 64.6±3.8%) and integrity (4 ml: 52.8±3.7%; 1 ml: 63.4±4.1%) compared to the methods employing silica colloidal-PVP (TM 4 ml: 30.0±3.6%; 1 ml: 45.9±4.3% and integrity 4 ml: 37.1±4.1%; 1 ml: 46.8±4.2%) and compared to the samples prior to sperm selection. Only the method using 4 ml of silica colloidal-PVP was not efficient (P>0.05) in selecting samples with better quality compared to the samples analyzed prior to sperm selection. The method using 1 ml of silica colloidal-silane was equally efficient to the method using 4 ml, presenting itself an alternative to process samples with lower sperm concentration.