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Abstract

This study investigated the impact of equilibration time on the quality of frozen-thawed semen in Pesisir bulls, focusing on post-thaw motility, viability, abnormalities, and intact plasma membrane. Semen samples were equilibrated for 2, 4, 6, 8, and 10 hours before freezing. Fresh semen had an average volume of 3.82mL, a sperm concentration of 762.5×106/mL, and motility of 73.75%. Post-thaw results showed that motility decreased with longer equilibration times, from 68.17% at 2 hours to 58.96% at 10 hours. Viability remained relatively stable, decreasing slightly from 73.38% at 2 hours to 68.88% at 10 hours. Abnormality rates improved, decreasing from 23.17% at 2 hours to 19.75% at 10 hours. The percentage of intact plasma membranes varied, peaking at 8 hours (54.38%) and declining to 46.29% at 10 hours. Correlation analysis revealed the following relationships: Post-Thawing Motility: ?=64.25+2.501X-0.304X2 (R²=0.987); Post-Thawing Viability: ?=74.13+0.036X-0.057X2 (R²=0.767); Post-Thawing Abnormality: ?=26.00-1.486X+0.084X2 (R²=0.963); Post-Thawing Intact Plasma Membrane: ?=47.03+1.487. X-0.140X2 (R²=0.135). These findings suggested that while longer equilibration times improved certain parameters, such as abnormalities, they adversely affected motility and membrane integrity. Identifying the optimal equilibration time was crucial for balancing these effects and enhancing the overall quality of frozen-thawed Pesisir bull semen for artificial insemination programs.