چکیده (انگلیسی):

Objective: To compare different cooling temperatures before ice formation on pig sperm
quality, before and after cryopreservation.
Methods: Semen diluted in BF5 was cooled from 23
C to 5
C (1% glycerol,
200 × 106 cells/mL). Sperm were packaged in plastic straws, and maintained at +5
C per
16 h. 1. Freezing point of diluted spermatozoa was determined by exposing straws to
nitrogen vapors. 2. Straws (at +5
C) were further cooled to −3
C, −5
C, and −7
C, and
rewarmed. 3. Straws (at +5
C) were further cooled to −3
C and −5
C, then frozen and
stored in liquid nitrogen, and one month later thawed. Progressive motility (PM), viability
(Eosin/Nigrosine), plasma membrane functionality (HOST), and acrosome integrity
(phase-contrast microscopy) were assessed.
Results: 1. Freezing point was −8.2 ± 0.3 (mean ± SEM); one of the ejaculates froze at
different temperature from that of the others (P < 0.05). 2. PM (%) was 75%, 71%, 63%,
and 40% (P < 0.05); viability (%) was 90%, 89%, 89%, and 81% (P < 0.05); HOST (%)
was 49%, 43%, 40%, and 25% (P < 0.05); Acrosome integrity (%) was 90%, 89%, 83%,
and 81% for +5, −3, −5, and −7
C respectively. 3. PM (%) was 35%, 37%, and 39%;
viability (%) was 57%, 60%, and 63%; HOST (%) was 22%, 22%, and 22%; acrosome
integrity (%) was 86%, 85%, and 86% for +5, −3, and −5
C respectively.
Conclusions: Cooling of pig sperm to −7
C (no freezing) damaged sperm function and
structure; in contrast, cooling to either −3
C or −5
C did not change pig sperm survival
after freeze-thawing.