The objective of this study was to uncover molecular and cellular dynamics in spermatozoa from Holstein bulls with Good (11 bulls) and Poor (5 bulls) cryotolerance. Post-thaw sperm kinetics, membrane integrity, and DNA fragmentation were assessed. Data was analyzed using principal component analysis. The spermatozoa from Good bulls had a higher number of cells with intact membranes (P = 0.029), nonragmented DNA (P = 0.018), post-thaw viability (P < 0.001) in comparison to those of the Poor bulls. The Good bulls also had a faster average path velocity (VAP; P = 0.017), straight-line velocity (VSL; P = 0.036), a greater distance average path (DAP; P = 0.006) and distance straight line (DSL; P = 0.011). No differences were found in total antioxidant capacity (TAC), number of live cells or other kinetic parameters between spermatozoa from Good and Poor groups, showing that no one characteristic can be used to determine cryotolerance.

Orientador: Frederico Ozanam Papa / Banca: João Carlos Pinheiro Ferreira / Banca: Alício Martins Junior / Resumo: A despeito das inúmeras variáveis que influenciam direta e indiretamente a fertilidade das fêmeas bovinas, a qualidade das amostras seminais exerce um papel importante na determinação das taxas de concepção dos programas de inseminação artificial. Os objetivos dessa pesquisa foram comparar a efetividade de dois diluidores de criopreservação de sêmen bovino no processamento de amostras seminais apresentando diferentes concentrações espermáticas em relação aos índices de congelabilidade determinados laboratorialmente (Experimento I) e as taxas de concepção proporcionadas por cada metodologia quando utilizada em programas de inseminação artificial em tempo fixo (IATF) em bovinos (Experimento II). No Experimento I foram utilizados 14 ejaculados de diferentes touros da raça Nelore. Cada ejaculado foi fracionado em oito alíquotas iguais, submetidas a criopreservação com os diluidores Tris-gema de ovo-frutose (meio TRIS) e MKA nas concentrações de 12, 25, 50 e 100 milhões de espermatozóides totais por mililitro de meio, formando oito grupos experimentais em função das variáveis diluidor e concentração. As amostras foram descongeladas a 46 ºC por 20 segundos, avaliando-se os padrões de motilidade através do método computadorizado (CASA), integridade de membrana plasmática (IMP), resistência ao teste de termorresistência rápido (TTR) e taxa de recuperação e IMP após seleção espermática pela técnica de swim-up. Para o Experimento II foram selecionados sete touros utilizados no Experimento I, obtendo-se um ejaculado de cada animal por eletroejaculação...(Resumo completo, clicar acesso eletrõnico abaixo) / Abstract: Although there are many variables which directly or indirectly influence female bovine fertility, the quality of sperm samples plays a important role in the determination of conception rates in artificial insemination programs. The aim of the present study was to compare the efficiency of two bovine semen extenders for sperm freezing with different spermatic concentrations in the freezability determined by lab tests (Experiment I), and conception rates after fixed time artificial insemination (FTAI; Experiment II). In Experiment I 14 ejaculates of different Nelore bulls were used. Each ejaculate was splitsampled in to eight equal parts and then submitted to cryopreservation with Tris-egg yolk fructose (TRIS) and MKA extenders, at concentrations of 12, 25, 50 and 100 millions spermatozoa per milliliter forming eight experimental groups. The samples were thawed at 46 ºC for 20 seconds, and the following parameters were evaluated: sperm motility and movement (by computer-assisted semen analysis - CASA), sperm membrane integrity (SMI), resistance to the fast thermoresistance test (TT), recovery rate and sperm membrane integrity after sperm selection through swim-up technique. Seven of 14 bulls used in Experiment I were selected for Experiment II, and semen was collected from each of the animals by electroejaculation. The seven ejaculates obtained were mixed (semen pool) and cryopreserved, thus forming eight experimental groups according to the freezing extenders and sperm concentrations/straws: TRIS 12, 25, 50 and 100, and MKA 12, 25, 50 and 100...(Complete abstract, click electronic address below) / Mestre

Made available in DSpace on 2014-06-11T19:29:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-02-26Bitstream added on 2014-06-13T19:38:31Z : No. of bitstreams: 1 crespilho_am_me_botfmvz.pdf: 507525 bytes, checksum: a1c92f545e77b50838125fbea8dfddd6 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A despeito das inúmeras variáveis que influenciam direta e indiretamente a fertilidade das fêmeas bovinas, a qualidade das amostras seminais exerce um papel importante na determinação das taxas de concepção dos programas de inseminação artificial. Os objetivos dessa pesquisa foram comparar a efetividade de dois diluidores de criopreservação de sêmen bovino no processamento de amostras seminais apresentando diferentes concentrações espermáticas em relação aos índices de congelabilidade determinados laboratorialmente (Experimento I) e as taxas de concepção proporcionadas por cada metodologia quando utilizada em programas de inseminação artificial em tempo fixo (IATF) em bovinos (Experimento II). No Experimento I foram utilizados 14 ejaculados de diferentes touros da raça Nelore. Cada ejaculado foi fracionado em oito alíquotas iguais, submetidas a criopreservação com os diluidores Tris-gema de ovo-frutose (meio TRIS) e MKA nas concentrações de 12, 25, 50 e 100 milhões de espermatozóides totais por mililitro de meio, formando oito grupos experimentais em função das variáveis diluidor e concentração. As amostras foram descongeladas a 46 ºC por 20 segundos, avaliando-se os padrões de motilidade através do método computadorizado (CASA), integridade de membrana plasmática (IMP), resistência ao teste de termorresistência rápido (TTR) e taxa de recuperação e IMP após seleção espermática pela técnica de swim-up. Para o Experimento II foram selecionados sete touros utilizados no Experimento I, obtendo-se um ejaculado de cada animal por eletroejaculação... / Although there are many variables which directly or indirectly influence female bovine fertility, the quality of sperm samples plays a important role in the determination of conception rates in artificial insemination programs. The aim of the present study was to compare the efficiency of two bovine semen extenders for sperm freezing with different spermatic concentrations in the freezability determined by lab tests (Experiment I), and conception rates after fixed time artificial insemination (FTAI; Experiment II). In Experiment I 14 ejaculates of different Nelore bulls were used. Each ejaculate was splitsampled in to eight equal parts and then submitted to cryopreservation with Tris-egg yolk fructose (TRIS) and MKA extenders, at concentrations of 12, 25, 50 and 100 millions spermatozoa per milliliter forming eight experimental groups. The samples were thawed at 46 ºC for 20 seconds, and the following parameters were evaluated: sperm motility and movement (by computer-assisted semen analysis - CASA), sperm membrane integrity (SMI), resistance to the fast thermoresistance test (TT), recovery rate and sperm membrane integrity after sperm selection through swim-up technique. Seven of 14 bulls used in Experiment I were selected for Experiment II, and semen was collected from each of the animals by electroejaculation. The seven ejaculates obtained were mixed (semen pool) and cryopreserved, thus forming eight experimental groups according to the freezing extenders and sperm concentrations/straws: TRIS 12, 25, 50 and 100, and MKA 12, 25, 50 and 100...(Complete abstract, click electronic address below)