The Thai Journal of Veterinary Medicine


The objective of this study was to compare the penetration rate of sperm, collected from two Landrace Boars A and B, into fresh, salt-stored and frozen, immature and matured oocytes. The first experiment, performed on immature oocytes, revealed that the penetration rates for the three groups of oocytes was from Boar A 59.6%(59/99), 78.1%(75/96) and 77.8%(77/99) (p<0.05) and the number of sperm penetration each oocyte was 2.79±0.42, 2.97±0.29 and 2.29±0.26 respectively (p>0.05). While for Boar B, the percentages were 65.3%(62/95), 76.8%(73/95) and 77.8%(77/99) with the number of sperm per oocyte being 2.25±0.28, 3.63±0.42 and 2.57±0.36. The highest values were found in the salt-stored group (p<0.05). The second experiment involved sperm penetration into in vitro mature oocytes. No differences were found for the sperm penetration rate and the number of sperm per oocyte using semen from Boar A which were 85.1%(74/87), 86.1%(56/65) and 89.1%(79/88) and 13.87±1.45, 17.69±2.61 and 14.45±1.75. While for Boar B, the lowest penetration rate was found when using fresh oocyte, lower than the two other groups; 52.6%(50/95), 67.3%(64/95) and 69.1%(67/ 97)(p<0.05). The number of sperm entering each oocyte was also inferior in the fresh oocytes than in salt-stored and frozen ones; 1.55±0.31, 2.80±0.35 and 2.87±0.40 (p<0.05) respectively. The conclusion that can be drawn from the experiment is that a) there are significant differences in the sperm penetration ability of different the boars used and b) the type of oocytes; immature vs. mature and fresh vs. salt-stored vs. frozen influenced the results that were obtained. It maybe possible to apply such an in vitro penetration assay to determine boar semen fertility under field conditions.

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