摘要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 ℃ to 5 ℃ (1% glycerol, 200 ×106 cells/mL). Sperm were packaged in plastic straws, and maintained at +5 ℃ per 16 hrs. 1. Freezing point of diluted spermatozoa was determined by exposing straws to nitrogen vapors. 2. Straws (at +5 ℃) were further cooled to -3 ℃, -5 ℃, and -7 ℃, and rewarmed. 3. Straws (at +5 ℃) were further cooled to -3 ℃and -5 ℃, 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 ℃ 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 ℃ respectively. Conclusions:Cooling of pig sperm to -7 ℃ (no freezing) damaged sperm function and structure; in contrast, cooling to either -3 ℃ or -5 ℃ did not change pig sperm survival after freeze-thawing.