An early prediction of semen quality by regular microscopic examination would help predicting donor sperm fertility ability thereby elevating the pregnancy rate of sows. It is not enough to accurately predict fertility ability of boar via the traditional semen assessment includes sperm concentration, vitality and morphology, and etc. Three R6 LRI Duroc boars at age of 2 years old (on average) were used in this study for assessment of semen quality in summer season (July, August, and September). All boars were not raised in wet pad and forced ventilation house. The results showed that respectively, in July, August and September, the semen volume was 240.00 ± 66.55, 182.50 ± 38.41 and 177.58 ± 61.71 mL; average semen density was 3.93 ± 9.2, 3.24 ± 8.89, 3.43 ± 1.45×108/mL; average sperm count was 897 ± 164, 571 ± 133 and 608 ± 216 ×108; percentage of live sperm was 89.67 ± 4.30, 85.52 ± 10.08 and 75.51 ± 22.00 %; percentage of live sperm with acrosome intact was 76.85 ± 6.14, 69.86 ± 14.37 and 60.64 ± 20.82 %; percentage of mitochondrial status was 17.33 ± 2.79, 21.81 ± 19.68 and 19.29 ± 13.86 %; and percentage of live sperm with normal structural chromosome was 93.48 ± 2.05, 96.23 ± 1.58 and 87.28 ± 27.37 %. These finding demonstrated that sperm quality of LRI Duroc boar not only did not influenced by summer heat stress, but even at high quality.

Key Words: LRI Duroc Pig, Sperm, Summer