Seasonal Variations in Semen Quality of Pasundan Bulls in their Native Tropical Environment

The success of artificial insemination highly depends on the semen quality, in which it may significantly associate with the environmental factor. However, the information regarding the seasonal effects on semen quality of Pasundan bulls is still scarce. This study aimed to examine seasonal variation in semen quality of Pasundan bulls in their native environment. A total of 203 ejaculates produced by two Pasundan bulls aged at four years old were used in this study. The bulls were kept under standard management conditions in Lembang Artificial Insemination Center. The results showed that mean values of semen volume, sperm concentration, total sperm number, individual sperm motility, post-thawing sperm motility and frozen semen production of Pasundan bulls were 5.7 mL, 1.17 billion/ml, 6.57 billion/ejaculate, 62.1,0 40.6 and 272% doses/ejaculate, respectively. Semen volume, individual sperm motility and post-thawing sperm motility were not affected by different seasons (P>0.05). Whereas, the significant reduction of sperm concentration (P<0.05), total sperm number (P<0.01) and frozen semen production (P<0.01) were observed in the dry season as compared to the rainy season. The minor change in ambient temperature, maximum ambient temperature, relative humidity and temperature-humidity index were detected between seasons. On the other hand, about 52% greater sunshine duration was detected in the dry season compared to the rainy season. In conclusion, the semen quality of Pasundan bulls is reduced during the dry season, which is considerably associated with the increase in sunshine duration.