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Optimising the use of fresh semen: insights for use with young genomically-selected bulls

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dc.contributor.advisor Fair, Seán
dc.contributor.author Holden, Shauna A.
dc.date.accessioned 2021-03-15T14:43:33Z
dc.date.available 2021-03-15T14:43:33Z
dc.date.issued 2017
dc.identifier.uri http://hdl.handle.net/10344/9879
dc.description peer-reviewed en_US
dc.description.abstract With the advent of genomic selection, bulls are being used in the artificial insemination industry during early puberty. These young bulls produce ejaculates of low volume and low spermatozoa concentration that are highly valued. The objective of this thesis was to investigate methods that best utilise the semen from young genomically-selected bulls. As a result of the characterisation of in vitro quality of sex-sorted (SS) and non-sex-sorted (NS) fresh and frozen spermatozoa there was ~40% of the SS fresh spermatozoa agglutinated while the SS (fresh and frozen) had lower levels of oxidative stress. Both motility and viability positively correlated to field fertility of SS spermatozoa, however, no functional assessments correlated to field fertility of NS spermatozoa. Different seminal plasma (SP) components were correlated to field fertility for both SS and NS cohorts. The effect of seminal plasma from high and low fertility bulls on the function of caudal epididymal spermatozoa was investigated via a number of in vitro assessments. Results from these assessment demonstrated a beneficial effect of SP on the motility of caudal epididymal spermatozoa (P<0.05). There was no effect of SP from high or low fertility bulls on fresh or frozen-thawed parameters assessed of caudal epididymal spermatozoa, or the fertilising ability of caudal epididymal spermatozoa. Seminal plasma reduced the osmotic resistance of caudal epididymal spermatozoa regardless of source form high or low fertility bull. Finally, this study sought to prolong the functional lifespan of spermatozoa in fresh egg yolk based diluent through the addition of antioxidants; l carnitine (0 to 20 mM), crocin (0 to 2 mM), α-tocopherol (0 to 1 mM), quercetin (0 to 250 µM) and catalase (0 to 500 IU). Following 4h at 39 o C incubation all catalase treated spermatozoa had greater acrosome intact populations compared to the control. When fresh semen was stored in the presence of antioxidants motility, lipid peroxidation and membrane fluidity decreased with time but there was no effect of treatment on any other the in vitro parameters assessed during the storage period. In conclusion, this thesis provides new insights into the physiological effects of sex-sorting on spermatozoa physiology. en_US
dc.language.iso eng en_US
dc.publisher University of Limerick en_US
dc.subject bulls en_US
dc.subject genomic selection en_US
dc.subject artificial insemination en_US
dc.title Optimising the use of fresh semen: insights for use with young genomically-selected bulls en_US
dc.type info:eu-repo/semantics/doctoralThesis
dc.type.supercollection all_ul_research en_US
dc.type.supercollection ul_published_reviewed en_US
dc.type.supercollection ul_theses_dissertations en_US
dc.rights.accessrights info:eu-repo/semantics/openAccess en_US


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