Effect of resveratrol supplementation in conventional slow and ultra-rapid freezing media on the quality and fertility of bull sperm.

The study investigated the impact of resveratrol (RES) on bull sperm cryopreservation employing conventional slow (CS) and ultra-rapid (UR) freezing methods on sperm quality and in vitro fertility. Twenty-four ejaculates from four bulls were divided into four groups based on the cryopreservation method and RES addition: CS-RES (n = 80), CS-Co (n = 80), UR-RES (n = 24), and UR-Co (n = 24). The CS freezing involved exposing sperm straws with 5% glycerol to liquid nitrogen (LN2) vapors, while UR freezing submerged sperm drops with 100 mM sucrose directly into LN2. Overall, sperm kinematic parameters and integrity of plasma and acrosome membranes significantly decreased (P < 0.001) after cryopreservation. Post-thaw values of motilities (total [TM] and progressive [PSM]), velocities (curvilinear and straight-line), beat cross frequency (BCF), and sperm with intact plasma membrane/intact acrosome (PI-/PNA-) were higher (P < 0.05) with CS-RES and CS-Co treatments compared to UR-RES and UR-Co treatments. CS-RES treatment resulted in greater percentages (P < 0.05) of TM, PSM, PI-/PNA-, and fertility (blastocyst rate) than their control, CS-Co; while UR-RES showed higher BCF values (P < 0.05) than its control, UR-Co. Additionally, UR-RES treatment exhibited lower oxidative stress percentages than UR-Co (P < 0.05). This study presents the following conclusions: (1) the CS freezing resulted in better cryosurvival of bull sperm than UR freezing; (2) the RES supplementation to CS freezing medium improved sperm motility, membrane integrity, and fertility; and (3) despite low cryosurvival sperm and fertility, the RES addition to ultra-rapid freezing medium reduced oxidative stress.

Egg Yolk-Supplemented Tris-Citric Acid Extender Improves the Prefreezing and Post-Thaw Sperm Quality Indices of Guinea Pig (Cavia porcellus) Epididymal Spermatozoa.

This study aimed to assess the suitability of egg yolk (EY) supplementation to a tris-citric acid-based extender on cryosurvival of guinea pig (Cavia porcellus) epididymal spermatozoa. Two synthetic-based extenders, tris-citric acid-glucose plus 20% EY (TCG-EY) and tris-citric acid-fructose (TCF) both with 5% glycerol, were compared. Thirty-two epididymides were recovered from 16 adult guinea pig males by gonadectomy, and then the sperm samples were retrieved by retrograde flushing using TCG-EY and TCF extenders for left or right epididymis, respectively. TCG-EY and TCF sperm samples were frozen in static liquid nitrogen vapors through a two-step cooling procedure. Before freezing, the percentage of progressive sperm motility and sperm with intact plasma and acrosome membranes from TCG-EY sperm samples were higher (p < 0.05) than those diluted with TCF. Post-thaw sperm kinematic variables and membrane integrity were drastically reduced (p < 0.001) compared with prefreezing samples, regardless of extender type. The post-thaw plasmatic and acrosome membrane integrity from TCG-EY sperm samples was higher (p < 0.05) than those from TCF samples. Except for the length, the morphometric head dimensions of sperm diluted with TCG-EY or TCF did not vary (p > 0.05) after the freezing-thawing process compared with the prefreezing samples. In conclusion, despite greater cell cryoinjury with both extenders, the EY supplementation exerted greater cell membrane protection before and after the freezing-thawing process. This research shows an in-depth analysis of guinea pig sperm cryopreservation; however, more studies are recommended.