Semen cryopreservation of Piau swine breed submited to three freezing protocols

Abstract

The objective of this study was to verify the effect of three protocols of cryopreservation on the sperm viability post-thawing of swine from the Piau breed (Sus scrofa), by means of evaluation assays in vitro and in vivo. Twenty-two ejaculates of 5 adult males of the Piau breed trough the gloved-hand method. In order to verify the sperm viability of the raw semen and post-thawing, the following traits were evaluated: sperm motility and vigor, hypoosmotic test, supra-vital color test and percentage of normal acrosomes. To freezing, the ejaculates were fractioned and submitted in: method 1, method of freezing recommended by Fürst et al. (2005), modified according to media extender; method 2, recommended by Fürst et al. (2005), modified according to the cooling curve; and method 3, recommended by Ohata et al. (2001). To test the in vivo fertility of the frozen/thawed semen, 23 intra-uterine (post-cervical) inseminations were performed in 14 females of the Piau breed, with semen from method 3. The mean values obtained with the use of methods 1 and 2 and post-thawing were inferior to those obtained with method 3. Four adult sows got pregnant (28.6% fertility rate). The freezing method recommended by Ohata et al. (2001), with balance period of 90 minutes at 22-26 ºC, enables higher results of in vitro sperm viability in comparison with the two other methods. The absence of balance period of method 1 and the cooling curve utilized in protocol 2 affect negatively the parameters of sperm viability evaluated in the present study. In spite of the satisfactory results in vitro for the freezing of semen with the utilization of method 3, it presents low fertility rate (28.6%).