Exame andrológico em carneiros: avaliação do efeito da criopreservação no sémen de carneiro e seu impacto sobre a fertilidade
Miniatura indisponível
Data
2019
Título da revista
ISSN da revista
Título do Volume
Editora
Resumo
Este estudo pretendeu: I- Descrever o procedimento do exame andrológico em
carneiros e relaciona-lo com a qualidade do sémen; II- Demonstrar as alterações
induzidas pela criopreservação e descongelação no sémen de carneiro; III- Comparar a
eficácia de dois extensores de sémen (OVIXCellÒ e Glucose-Citrato-Gema de ovo); IV–
Determinar os Índices de Fertilidade, Natalidade e número médio de borregos por parto
resultantes da inseminação artificial com sémen refrigerado e descongelado.
Através da estatística de Pearson, determinou-se uma correlação positiva
entre os vários parâmetros do exame andrológico e a qualidade do sémen. A
concentração apresentou uma correlação forte (r=0,8), A circunferência escrotal
(r=0,59), motilidade (r=0,59), volume (r=0,58) e morfologia (r=0,46) apresentaram
correlações médias. Os resultados permitem afirmar com alguma segurança que um
carneiro “Apto para Reprodução” produzirá um ejaculado de boa qualidade.
Foram feitas 13 sessões de colheitas de sémen. O sémen obtido foi submetido
a um protocolo de congelação com dois extensores diferentes; OVIXCellÒ e Glucose-
Citrato-Gema de ovo. Todas as amostras de sémen foram avaliadas antes da
criopreservação e após a descongelação, quanto á motilidade, vitalidade e morfologia.
A criopreservação e descongelação têm um impacto bastante negativo na
viabilidade do sémen, independentemente do extensor utilizado. Registou-se um
decréscimo de 50% na motilidade progressiva; de 40% na vitalidade espermática e um
aumento de 20% de espermatozoides com morfologia anormal. A utilização de Glucose-
Citrato-Gema de ovo mostrou-se vantajosa relativamente à utilização de OVIXCellÒ por
apresentar um perfil de alterações menos significativo à descongelação. O sémen
diluído com OVIXCellÒ teve uma perda de motilidade 10% superior, de vitalidade 7%
superior e uma contagem de espermatozoides com morfologia anormal 23% superior
quando comparado com o sémen diluído com Glucose-Citrato-Gema de ovo.
Relativamente ao índice de Fertilidade e Natalidade, a preparação de doses de
inseminação artificial com 50x106spz viáveis/dose poderá compensar a fraca viabilidade
do sémen descongelado aplicado por laparoscopia. A utilização desta concentração
permitiu obter índices de fertilidade de 34% e de natalidade de 42%, ambos satisfatórios
relativamente aos índices descritos na bibliografia. Os resultados não foram conclusivos
quanto á média de borregos por parto.
This study aimed to: I- Describe the procedure of the breeding soundness evaluation in rams and relate it to the quality of semen; II– Demonstrate the changes induced by cryopreservation and thawing in ram semen; III - Compare the change profile induced by freezing and thawing in semen extended with OVIXCellÒ and with Glucose- Citrate-Egg yolk); IV– Determine the Fertility and Birth rates and average of lambs per lambing resulting from artificial insemination with refrigerated and thawed semen. Using Pearson’s statistics, determined a positive correlation between the various parameters of the breeding soundness evaluation and the quality of semen. Concentration had a strong correlation (r = 0.8); scrotal circumference (r = 0.59), motility (r = 0.59), volume (r = 0.58) and morphology (r = 0.46) had medium correlations. This analysis allows us to assert, that a "Suitable for Reproduction" ram will produce a good quality ejaculate. Thirteen semen collection sessions were carried out. Collected semen was submitted to a freezing protocol with two different extenders; OVIXCellÒ and Glucose- Citrate-Egg Yolk. All semen samples were evaluated before freezing and after thawing for motility, vitality and morphology. Cryopreservation and thawing had a very negative impact on semen viability, regardless of the used extender. It was noted, a 50% decrease in progressive motility, a 40% decrease in sperm vitality and a 20% increase in abnormal morphology count. The use of the Glucose-Citrate-Egg Yolk Extender was advantageous over the use of OVIXCell® because it presented a less significant change profile after thawing. Semen extended with OVIXCellÒ had 10% higher motility loss, 7% higher vitality loss and a 23% higher abnormal sperm morphology count when compared to semen diluted with Glucose-Citrate-egg yolk. Regarding the Fertility and Birth rates, artificial insemination with a concentration of 50x106 viable spz/dose may compensate for the poor viability of thawed semen when applied by intrauterine laparoscopy. Insemination of sheep with these concentrations resulted on a fertility rate of 34% and a 42% birth rate. These rates are satisfactory relative to those described in literature. Results were not conclusive regarding the average number of lambs per lambing.
This study aimed to: I- Describe the procedure of the breeding soundness evaluation in rams and relate it to the quality of semen; II– Demonstrate the changes induced by cryopreservation and thawing in ram semen; III - Compare the change profile induced by freezing and thawing in semen extended with OVIXCellÒ and with Glucose- Citrate-Egg yolk); IV– Determine the Fertility and Birth rates and average of lambs per lambing resulting from artificial insemination with refrigerated and thawed semen. Using Pearson’s statistics, determined a positive correlation between the various parameters of the breeding soundness evaluation and the quality of semen. Concentration had a strong correlation (r = 0.8); scrotal circumference (r = 0.59), motility (r = 0.59), volume (r = 0.58) and morphology (r = 0.46) had medium correlations. This analysis allows us to assert, that a "Suitable for Reproduction" ram will produce a good quality ejaculate. Thirteen semen collection sessions were carried out. Collected semen was submitted to a freezing protocol with two different extenders; OVIXCellÒ and Glucose- Citrate-Egg Yolk. All semen samples were evaluated before freezing and after thawing for motility, vitality and morphology. Cryopreservation and thawing had a very negative impact on semen viability, regardless of the used extender. It was noted, a 50% decrease in progressive motility, a 40% decrease in sperm vitality and a 20% increase in abnormal morphology count. The use of the Glucose-Citrate-Egg Yolk Extender was advantageous over the use of OVIXCell® because it presented a less significant change profile after thawing. Semen extended with OVIXCellÒ had 10% higher motility loss, 7% higher vitality loss and a 23% higher abnormal sperm morphology count when compared to semen diluted with Glucose-Citrate-egg yolk. Regarding the Fertility and Birth rates, artificial insemination with a concentration of 50x106 viable spz/dose may compensate for the poor viability of thawed semen when applied by intrauterine laparoscopy. Insemination of sheep with these concentrations resulted on a fertility rate of 34% and a 42% birth rate. These rates are satisfactory relative to those described in literature. Results were not conclusive regarding the average number of lambs per lambing.
Descrição
Orientação: Carlos Manuel Varela Bettencourt
Palavras-chave
MESTRADO INTEGRADO EM MEDICINA VETERINÁRIA, VETERINÁRIA, MEDICINA VETERINÁRIA, OVINOS, EXAMES ANDROLÓGICOS, INSEMINAÇÃO ARTIFICIAL VETERINÁRIA, FERTILIDADE, REPRODUÇÃO ANIMAL, VETERINARY MEDICINE, SHEEP, BREEDING SOUNDNESS EXAMINATION, ARTIFICIAL INSEMINATION OF ANIMALS, FERTILITY, ANIMAL BREEDING, CRIOPRESERVAÇÃO DE SÉMEN, SEMEN CRYOPRESERVATION