Browsing by Author "Tamay Siguenza, Erika Fabiola"

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    Efecto de la melatonina en la criopreservacion de espermatozoides equinos
    (2018) Tamay Siguenza, Erika Fabiola; Vélez Sandoval, Frixon Augusto; Soria Parra, Manuel Elías
    The objective of this research was to evaluate the effect of melatonin in the cryopreservation of equine spermatozoa. Three Appaloosa horses from farms located in the Victoria del Portete parish, Azuay Province, were used. Semen samples were collected twice a week, with an artificial vagina, until five ejaculates per animal were complete. Treatment, stallion and repetition were considered as independent variables, whereas as dependent variables were studied the individual progressive motility, the percentages of spermatozoa live/dead, with abnormalities, with the intact plasma and acrosomal membrane, undergoing oxidative stress, bovine oocytes fertilized by equine sperm. Data were processed by the analysis of variance of SAS. The post-thaw evaluation indicated that the semen diluted without melatonin had a greater percentage of live sperm (85.1 ± 1.7 vs 80.0 ± 1.7%) and less sperms with the intact plasma membrane (25.2 ± 1.8 vs 31.3 ± 1.8% respectively) than with melatonin (P<0.05). The proportion of sperm without oxidative stress and with slight or moderate stress were statistically similar between treatments. Regarding to heterologous in vitro fertilization (IVF), it was found that there was no difference between treatments in the percentages of union, penetration, polyspermia and pronuclei by 18 and 24 hours. However, a greater percentages of union, of pronuclei by 18 and 24 hours and of cleavage was observed in the homologous than in the heterologous IVF.
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    Effect of melatonin and caffeine supplementation to freezing medium on cryosurvival of peruvian paso horse sperm using a two-step accelerating cooling rate
    (2022) Dorado , Jesús; Saa, Luis Rodrigo; Galarza Lucero, Diego Andrés; Santiago Moreno, Julián; Tamay Siguenza, Erika Fabiola; Palacios Aguilar, María Paula; Pelaez Zhingri, Gabriela Micaela
    This research examined the antioxidant and cryoprotective effects of melatonin (ME) and caffeine (CAF) supplementation in freezing medium on the cryosurvival of Peruvian Paso horse sperm using a two-step accelerating cooling rate. Twenty ejaculates from four adult and fertile stallions were recovered, initially diluted with INRA-96 , and finally frozen with INRA-Freeze  with either no supplementation (as control), 1 mM ME, or 2mM CAF using a two-ramp freezing system content inside a cryogenic-box and liquid nitrogen vapors. The sperm kinematic parameters and integrity of the plasma and acrosomal membranes of fresh semen and cryopreserved samples were evaluated using the CASA system (SCA-Evolution  2018) and PI/fluorescein isothiocyanate-conjugated peanut (Arachis hypogaea) agglutinin double fluorescent test, respectively. The oxidative stress of post-thaw sperm samples was also assessed using the CellRox Deep Red fluorescence test. The results showed that curvilinear velocity and average-path velocity were greater ( p < 0.05) after freezing with CAF than the control group. In addition, there were significance differences ( p < 0.01) between stallions (1–4) in post-thaw kinematic parameters regardless of ME or CAF addition. Both ME and CAF improved (p < 0.05) the proportion of sperm with intact plasma membranes and intact acrosomes. Nevertheless, neither CAF nor ME improved the oxidative stress after the cryopreservation process.