Boar semen encapsulation in barium alginate has recently been proposed for artificial fecundation to obtain the controlled release of the spermatozoa and reduce the number of instrumental insemination (1, 2). The semen encapsulated using this technique preserved membrane and acrosome integrity and showed good motility. In this work an in vitro fertilization test was carried out in different seasons of the year to verify if the encapsulation process could impair the fertilization ability of the spermatic cells. Mixed semen from two Large White boars (sperm concentration > 4xl0~8 cells/mL; motility > 90 %; average velocity > 60 mu m/sec) was added of BaCl_2 saturated solution, to obtain a 0.02M barium concentration and dropped into a 0.5 % w/v sodiumalginate solution (Sodium Alginate Medium Viscosity, Sigma-Aldrich, D). The capsules were rinsed and suspended in a standard extender for swine sperm. A fraction of the capsules was employed for the in vitro fertilization test (A cps) and the other fraction was cross-linked with a 1% w/v solution of protamine sulphate (Sigma-Aldrich, D) for 20 min (B cps). Five batches have been produced in different seasons of the year. Multiparous sows ovarian follicles were collected after slaughtering and transferred into culture medium BSA-free NCSU-23 (3) supplemented with porcine follicular fluid, cysteine, equine and human chorionic gonadotropins for the in vitro maturation (4). After incubation (22 hours, followed by a 22-hours incubation without hormones), oocytes were decumulated and immediately put into mTBM medium (4); 30-40 oocytes were included in each medium drop (50 mu L). Spermatozoa were aspirated from the capsules, diluted until a concentration of 5x10~5 cells/mL, capacitated and added to each dropfor fertilization (total volume of drop: 100 mu L). The coincubation lasted 6 hours and then the oocytes were put into culture medium. The zygotes were microscopically observed after 96 hours of incubation and classed in "cleaved" or "not cleaved". In each test the oocyte pool has been divided in three groups: the first was treated with refrigerated commercial semen as control, the second and the third was treated with the semen contained in A and B cps respectively.
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