Author/Authors :
A. Morrier، نويسنده , , Nigel J.L Bailey، نويسنده ,
Abstract :
For artificial insemination (AI) in the pig, semen is routinely maintained at room temperature
for 2–4 h prior to extending—to reduce the cooling damage to sperm during
cryopreservation. In the sheep industry, however, semen is diluted and cooled immediately
after collection. This trial evaluated the effect of a 4 h pre-incubation period for semen
at room temperature on the subsequent quality parameters of ram sperm prepared for
AI. Immediately following collection, ram semen was divided in 2 aliquots—one was left
undiluted for 4 h at room temperature (20 ◦C; pre-incubation) and the other (control) was
diluted with an egg-yolk-based extender and either cooled to 5 ◦C (n = 8 different ejaculates)
for short-term fresh conservation or cryopreserved (n = 6 different ejaculates). After
4 h at room temperature, the pre-incubated semen was then diluted and either cooled to
5 ◦C or cryopreserved, as was the control. Sperm motility, viability and chlortetracycline
(CTC) pattern distribution of the pre-incubated semen were compared to the control. For
fresh semen conserved at 5 ◦C, total sperm motility and the proportion of CTC pattern F
sperm (referring to non-capacitated, non-acrosome reacted cells) were reduced by the 4 h
incubation at room temperature, compared to the control. The effect of pre-incubation at
room temperature was more evident in the cryopreserved semen in terms of total and progressive
sperm motility, with the viability being reduced following pre-incubation. For the
cryopreserved semen, the percentage of CTC pattern F sperm declined, while the pattern
of AR sperm (referring to acrosome-reacted cells) increased, compared to the controls. In
conclusion, pre-incubation of ram semen for 4 h at room temperature prior to preparation
for AI is not beneficial to the subsequent functionality of the sperm. Furthermore, this
pre-incubation period is more harmful to frozen-thawed than to fresh-cooled sperm
