| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 1.73 MB | Adobe PDF |
Authors
Abstract(s)
O processo de criopreservação é responsável pela diminuição da qualidade seminal
e torna mais clara a existência de uma variabilidade individual na qualidade do sémen
descongelado. O principal objetivo do estudo foi analisar a variabilidade individual na
criopreservação de sémen de bodes de raça Serpentina, no que diz respeito à
congelabilidade dos seus ejaculados, através de uma avaliação subjetiva, de testes
complementares e de uma avaliação objetiva. Descongelaram-se 40 palhinhas de sémen
criopreservado obtidas a partir de ejaculados de 7 bodes, que foram examinadas por
microscopia ótica para a avaliação da motilidade espermática progressiva (%) e foram
realizados esfregaços para determinar a vitalidade e a percentagem de anisoespermia. Para
avaliar a integridade das membranas plasmáticas dos espermatozoides, as amostras foram
submetidas ao teste hipo-osmótico (HOST) e para avaliar o comportamento e resistência
dos espermatozoides foram submetidas ao teste de termorresistência (TTR). Por último, foi
realizada uma avaliação objetiva da cinética espermática através do sistema CASA. A
percentagem de motilidade foi reduzida significativamente (p<0,001) de 80,88% no sémen
fresco para 48,5% após a descongelação. Durante o estudo, os ejaculados foram
classificados pelo nível de congelabilidade, de acordo com a sua motilidade pós descongelação: alto (>30%) e baixo (≤30%). Ejaculados com nível de congelabilidade alto
apresentaram valores de motilidade (p<0,001), vitalidade (p<0,05) e de motilidade aos
120min do TTR (p<0.001) significativamente superiores aos de baixa congelabilidade. Na
avaliação através do sistema CASA foram observadas diferenças estatisticamente
significativas entre os ejaculados de congelabilidade alta e baixa nos seguintes parâmetros:
MOT (p<0,001), MOTP (p<0,001), VAP (p<0,001), VCL (p<0,001), VSL (p<0,05), ALH
(p<0,05), RAPID (p<0,001), MED (p<0,001) e STATIC (p<0,001). Considerou-se, neste
estudo, que um bode que produz sémen de alta qualidade e congelabilidade teria de
apresentar uma motilidade pós-descongelação média >30% e covariância <0,1. Assim,
apenas os bodes 2121 e 2808 foram considerados indivíduos produtores de sémen de
qualidade superior. Porém, só foram encontradas diferenças estatisticamente significativas
entre indivíduos quanto à vitalidade, aos 5min do TTR e ao BCF. Este estudo demonstrou
não existir uma variabilidade individual marcada na qualidade do sémen criopreservado dos
bodes estudados. No entanto, os elevados valores de desvio padrão demonstram que os
ejaculados de um mesmo macho são bastantes variáveis nas suas características seminais.
A classificação e comparação dos ejaculados pelo seu nível de congelabilidade mostraram
ser apropriadas e revelaram diferenças importantes na qualidade do sémen descongelado
de bode.
ABSTRACT - Individual variability of cryopreserved semen in Serpentina bucks - The cryopreservation process is responsible for the reduction of semen quality and makes clearer the existence of individual variability in the quality of thawed semen. The main objective of this study was to analyze the individual variability in the cryopreservation of Serpentino buck’s semen regarding the freezability of their ejaculates through a subjective evaluation, complementary tests and an objective evaluation. 40 straws of cryopreserved semen, referring to ejaculates of 7 bucks, were thawed and examined trough optical microscopy to evaluate the progressive motility of the sperm (%), smears were performed to determine sperm vitality and the percentage of sperm defects. To evaluate the integrity of the sperm’s plasma membranes, the samples were subjected to the hypoosmotic test (HOST) and to evaluate the sperm’s behavior and resistance the samples were subjected to the thermoresistance test (TTR). Lastly, the objective evaluation of sperm kinetics through a CASA system was performed. Sperm motility was significantly reduced (p<0.001) from 80.88% in fresh semen to 48.5% after thawing. In this study, the ejaculates were classified by their freezability level, according to their post-thaw motility: high (>30%) and low (≤30%). Ejaculates with high level of freezability showed motility (p<0.001), vitality (p<0.05) and motility at the TTR 120min (p<0.001) values that were significantly higher than the values of the low freezability ejaculates. The evaluation through the CASA system showed statistically significant differences between the ejaculates with different freezabily levels in the following parameters: MOT (p<0.001), MOTP (p<0.001), VAP (p<0.001), VCL (p<0.001), VSL (p<0.05), ALH (p<0.05), RAPID (p<0.001), MED (p<0.001) e STATIC (p<0.001). It was considered, in this study, that a buck that produces high quality and freezability semen must present a mean post-thaw motility >30% and covariance <0.1; therefore, only the bucks 2121 and 2808 were considered individual producers of semen of superior quality. However, the only significant differences found between individual bucks were in regard of vitality, TTR 5min and BCF. This study showed that it does not exist a clear individual variability of the quality of cryopreserved semen of the bucks studied. However, the elevated standard deviation values show that ejaculates of the same individual are quite variable in their seminal characteristics. Therefore, the evaluation and comparison of ejaculates by their freezability level proved to be appropriate and revealed important differences in the quality of post-thaw buck semen.
ABSTRACT - Individual variability of cryopreserved semen in Serpentina bucks - The cryopreservation process is responsible for the reduction of semen quality and makes clearer the existence of individual variability in the quality of thawed semen. The main objective of this study was to analyze the individual variability in the cryopreservation of Serpentino buck’s semen regarding the freezability of their ejaculates through a subjective evaluation, complementary tests and an objective evaluation. 40 straws of cryopreserved semen, referring to ejaculates of 7 bucks, were thawed and examined trough optical microscopy to evaluate the progressive motility of the sperm (%), smears were performed to determine sperm vitality and the percentage of sperm defects. To evaluate the integrity of the sperm’s plasma membranes, the samples were subjected to the hypoosmotic test (HOST) and to evaluate the sperm’s behavior and resistance the samples were subjected to the thermoresistance test (TTR). Lastly, the objective evaluation of sperm kinetics through a CASA system was performed. Sperm motility was significantly reduced (p<0.001) from 80.88% in fresh semen to 48.5% after thawing. In this study, the ejaculates were classified by their freezability level, according to their post-thaw motility: high (>30%) and low (≤30%). Ejaculates with high level of freezability showed motility (p<0.001), vitality (p<0.05) and motility at the TTR 120min (p<0.001) values that were significantly higher than the values of the low freezability ejaculates. The evaluation through the CASA system showed statistically significant differences between the ejaculates with different freezabily levels in the following parameters: MOT (p<0.001), MOTP (p<0.001), VAP (p<0.001), VCL (p<0.001), VSL (p<0.05), ALH (p<0.05), RAPID (p<0.001), MED (p<0.001) e STATIC (p<0.001). It was considered, in this study, that a buck that produces high quality and freezability semen must present a mean post-thaw motility >30% and covariance <0.1; therefore, only the bucks 2121 and 2808 were considered individual producers of semen of superior quality. However, the only significant differences found between individual bucks were in regard of vitality, TTR 5min and BCF. This study showed that it does not exist a clear individual variability of the quality of cryopreserved semen of the bucks studied. However, the elevated standard deviation values show that ejaculates of the same individual are quite variable in their seminal characteristics. Therefore, the evaluation and comparison of ejaculates by their freezability level proved to be appropriate and revealed important differences in the quality of post-thaw buck semen.
Description
Dissertação de Mestrado Integrado em Medicina Veterinária
Keywords
Sémen bode Serpentina CASA congelabilidade Semen buck Serpentina CASA freezability
Pedagogical Context
Citation
Leites IJC 2021. Variabilidade individual do sémen criopreservado em bodes de raça serpentina [dissertação de mestrado]. Lisboa: FMV-Universidade de Lisboa.
Publisher
Universidade de Lisboa, Faculdade de Medicina Veterinária