Animal Reproduction Science 92 (2006) 334–348 In vitro penetration of fresh and vitrified swine oocytes by homologous spermatozoa using different incubation systems Milton C. Macedo Jr., Jo˜ ao C. Deschamps ∗ , Thomaz Lucia Jr., Jonas Bordignon, Carolina G. Serret, Gissele Rambo, Ivo Pivato, Eduardo Schmitt Faculdade de Veterin´ aria, Centro de Biotecnologia, Universidade Federal de Pelotas, 96010-900 Pelotas-RS, Brazil Received 15 December 2004; received in revised form 15 April 2005; accepted 9 May 2005 Available online 25 July 2005 Abstract The present study consisted of two experiments. In the first one, ejaculates from four boars were used to compare in vitro penetration (IVP) rates of fresh and vitrified swine oocytes by homologous spermatozoa in four treatments: fresh oocytes in conventional incubation (CO 2 incubator) (FC), vit- rified oocytes in conventional incubation (VC), fresh oocytes in submarine (bag) incubation (FS) and vitrified oocytes in submarine incubation (VS). The IVP rates for FC, VC, FS and VS were 46.5, 44.3, 36.9 and 33.1%, respectively. Analysis through Chi-square tests identified no differences in IVP rates between FC and VC and between FS and VS (P > 0.05), but IVP rate for FC was greater (P < 0.05) than those for both FS and VS. Besides IVP rate for VC did not differ (P > 0.05) from those for FC and FS, but it was greater than that for VS (P < 0.05). Logistic regression analysis identified differential effects of treatments dependant on individual boars. The second experiment evaluated the influence of semen storage period on the semen quality of the two boars associated with greater IVP rate in the first experiment. Semen quality was estimated by IVP rate using the VC treatment and by the following methods: sperm motility, sperm morphology, hypoosmotic swelling test (HOST) and thermal stress test (TST). According to analysis using Chi-square tests, IVP rate did not differ (P > 0.05), for the first boar, between 0 (100.0%) and 24 h of semen storage (98.1%) nor after 48 and 72 h (66.0 and 59.3%, respectively), but IVP rates were greater during the 0–24 h period compared with the 48–72 h ∗ Corresponding author. Tel.: +55 53 275 7588; fax: +55 53 275 7551. E-mail address: deschamp@ufpel.edu.br (J.C. Deschamps). 0378-4320/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.anireprosci.2005.05.030