Abstract: To study the effects of seasonal varitions on seminal quality and productivity including the average collected volume, the average density, the average activity, the rate of semen utilization and the number of frozen semen tubule in bulls, 20 bulls of different breeds were selected which were 3 to 4.5 years old. The results showed that the semen density of Luxi bulls was the highest in spring and summer (P＜0.01), and whose sperm activity was significantly lower than other seasons in autumn(P＜0.01), and the rate of semen utilization and the number of frozen semen tubule were significantly reduced simultaneously in summer and autumn(P＜0.05). For Montbeliate, the semen collected volume was the most in summer(P＜0.05), the semen density in summer and autumn was significantly lower than that in spring(P＜0.05,P＜0.01), the sperm activity in summer was the lowest among the whole year, and was significantly lower than that in spring(P＜0.05), and the variations the rate of semen utilization and the number of frozen semen tubule were similar to that of Luxi bulls. The semen collected volume of German Simmental was significantly rising in summer(P＜0.05), the semen density in autumn was significantly lower than that in spring(P＜0.05), the sperm activity in summer and autumn was significantly lower than that in spring and winter(P＜0.01,P＜0.05), and the rate of semen utilization and the number of frozen semen tubule in spring were significantly higher than those in the other seasons(P＜0.05,P＜0.01). In conclusion, there were some effects on seminal quality and productivity in bulls of different breeds when the seasons changed, and the effects was the smallest to Luxi bulls.

Key words: season; bull; semen quality; productivity