In vitro Evaluation of the Quality and Fertilizing Capacity of Boar Semen Frozen in 0.25 ml straws

Abstract

Twenty-two boar ejaculates were frozen in 0.25 ml straws using a controlled cooling rate, then evaluated in vitro in order to assess: (i) the extent to which a range of semen evaluation parameters accurately characterize sperm quality, (ii) the value of quality assessment in the characterization of long-term sperm survival and fertility and (iii) the suitability of the cryopreservation protocol used for yielding semen with good quality and fertilizing capacity. Motility with or without caffeine, plasma membrane integrity (PMI) evaluated with both propidium iodide (PI) and Hoechst 33258, and acrosome morphology were studied, the ejaculates being then classified into five quality groups. A thermoresistance test and a homologous in vitro fertilization test were applied to selected ejaculates of these groups. Caffeine-stimulated motility and PMI evaluated with PI provided better estimations of semen quality than the other tests of motility, PMI, or acrosome morphology, but this quality assessment could not reveal differences in fertilizing capacity or thermoresistance among ejaculates. Over 43% spermatozoa survived cryopreservation in 19 of the 22 ejaculates, with inter-boar and inter-ejaculate variability in the freezing success being observed. The fertilizing capacity, however, was seriously affected by the process regardless of the semen quality. It is concluded that caffeine-stimulated motility and PMI evaluated with PI give accurate information on sperm quality, but important aspects to the valuation of semen such as thermoresistance and fertilizing capacity are not revealed by this quality study. Moreover, the approach of selecting suitable protocols of cryopreservation does not appear to be sufficient for guaranteeing systematically good quality and fertilizing capacity in the frozen-thawed semen.

Effect of the Pre-Freezing Treatment of Boar Sperm With Cholesterol-Loaded Cyclodextrins on the Functionality and the Fertilizing Ability of the Sperm After Cryopreservation

“…As expected, sperm quality decreased in a time-dependent manner when the frozenthawed samples were incubated at 37 ºC, which is similar to what was observed in previous reports (Peláez et al, 2006). However, our data indicate that the frozen-thawed samples maintain their motility for at least 6 h and their viability for 24 h when they are stored at 16 ºC.…”

Spermometer: electrical characterization of single boar sperm motility

“…To show the effect of chemical stimulation on single sperm motility and to investigate whether this effect can be measured electrically, trapped sperm cells were exposed to caffeine (SI text). Moderate intake of caffeine did not show an effect on the sperm motility in a human population (33); however, direct exposure to this compound in vitro is known to increase sperm motility (31).…”

“…Furthermore, several chemical compounds are known to alter the swimming behavior of sperm including P (30), caffeine (31), and calcium ionophore A23187 (32). To show the effect of chemical stimulation on single sperm motility and to investigate whether this effect can be measured electrically, trapped sperm cells were exposed to caffeine (SI text).…”

Concentração de lactato de cálcio e tempo de incubação sobre a capacidade de adesão e penetração de espermatozoides suínos na membrana perivitelina do ovo da galinha

“…Entre os testes que podem ser utilizadas para predizer a fertilidade de machos suínos, podem ser citados: o teste de penetração espermática in vitro em ovócitos homólogos (LARSSON & RODRÍGUES-MARTÍNEZ, 2000;POPWELL & FLOWERS, 2004;MACEDO et al, 2006;e o teste de fertilização in vitro (PELÁEZ et al, 2006). Entretanto, esses testes são relativamente trabalhosos e onerosos, inviabilizando a sua utilização na rotina de centrais de IA, o que justifica o desenvolvimento de outros métodos de avaliação in vitro.…”