Tesis doctoral de Isabel Casas Roqueta
The use of frozen-thawed (ft) sperm in artificial insemination (ai) of species with productive interest allows higher sanitary control and the creation of high genetic value sperm banks, among other advantages. In the swine market, most inseminations are still performed with refrigerated semen (fs) because of the successful application of long-term extenders and the sensitivity of boar sperm to cryopreservation. Although this sensitivity is provided by particular features of the sperm physiology in boars, some boar ejaculates maintain the sperm quality parameters after freezing (good freezability ejaculates, gfes) in front of others that do not survive the process (poor freezability ejaculates, pfes). The first objective of the study was to compare both groups in terms of field fertility. The second objective was to test the efficiency of the post-cervical ai (post-cai) with ft sperm. The third objective was to search for predictors of the ejaculate freezability by assessing, both in gfes and in pfes and in three steps during the cryopreservation procedure (17ºc, 5ºc and 240 min post-thaw), conventional sperm quality parameters and the location and reactivity, under the microscope, of three proteins related to the sperm physiology with potential roles in freezability (glut3, hsp90aa1 and cu/znsod). The fourth objective was to quantify, through western blotting, the expression of the three proteins, both in gfes and in pfes and in the three steps mentioned, to determine their potential as freezability predictors. For the first and second objectives, 86 sows were inseminated by post-cai with 26 ejaculates from piétrain boars divided into a 17ºc fs portion (control treatment) and a cryopreserved (ft) sperm portion, the two portions in turn classified into gfes and pfes. The most relevant outcomes were that the probabilities of pregnancy resulted two times lower after inseminations with ft-pfes (p < 0.05) compared to ft-gfes, which indicates that ejaculates with high post-thaw sperm progressive motility and membrane integrity (over 40% in gfes) are more likely to result in pregnancies than those with poor in vitro sperm function (pfes). Neither the number of farrowing sows and the litter size nor the risk of sperm backflow was significantly different in ft-gfes from that achieved in fs control treatments, which showed the good applicability of post-cai to boar ft sperm. For the third and fourth objectives, 29 and 11 piétrain boar ejaculates, respectively, were cryopreserved. Two kinematic indices, the sperm linearity (lin) and the sperm straightness (str), revealed higher hyperactivated motility in pfes than in gfes when assessed after 30 min at 5ºc during cryopreservation, the combination of the two motility parameters showing around 72% confidence in the freezability prediction of ejaculates. Whereas it was not possible to predict the freezability of the boar ejaculates by assessing the three proteins under microscope, results from western blot showed differences in the hsp90aa1 expression in sperm at 17ºc that are most possibly related to the best cryosurvival of gfes. This finding aims to promote the cryopreservation of boar sperm intended for use in ai through the development of tests for freezability prediction in fs.
Datos académicos de la tesis doctoral «A practical approach on boar sperm cryodamage. morphofunctional and immunocytochemical study of cryopreserved boar sperm intended for use in artificial insemination.«
- Título de la tesis: A practical approach on boar sperm cryodamage. morphofunctional and immunocytochemical study of cryopreserved boar sperm intended for use in artificial insemination.
- Autor: Isabel Casas Roqueta
- Universidad: Girona
- Fecha de lectura de la tesis: 08/07/2010
Dirección y tribunal
- Director de la tesis
- Sergi Bonet Marull
- Tribunal
- Presidente del tribunal: merce Durfort coll
- carmen Matas parra (vocal)
- montserrat Ponsa fontanals (vocal)
- pilar Coy fuster (vocal)