| The test animals for this study were selected from Jilin Changchun Bull Station. 20 bulls were chosen by similiar age, body condition and good libido. Production performance indices of these bulls were statistically analyzed base on the three consecutive years(2013 ~ 2015) productive records of four seasons(from March to May for Spring, from June to August for Summer, from September to November for Autumn, from December to February for Winter). The analysis results of the first part are as following items.1.The bull semen quality in this study changes with seasonal temperature and humidity changes of the four seasons. In this paper, temperature humidity index(THI) is used as a key factor for the seasonal changes in Changchun, the spring temperature humidity index, the summer temperature humidity index, autumn temperature humidity index and the winter temperature humidity index. This can intuitively discribe the seasonal changes effect on bull semen quality. Temperature humidity index expression formula is THI=0.72(Tw+Td)+40.6(Tw, Td for dry and wet bulb temperature meter readings). It refers toenvironment temperature humidity index of the barn.2.The change of fresh semen volume in different seasons was not significant(P > 0.05), but fresh semen volume for individual bulls exist significant difference(P < 0.05), of which the fresh semen volume of 11345 is the largest, while 11035 is the smallest.3.Bull sperm vitality in the summer(0.66 ± 0.04) and spring(0.81±0.01) and autumn(0.79±0.01), winter(0.68 ± 0.04) is extremely significant difference(P < 0.01). sperm vitality in Autumn increased significantly than in summer, but in the winter, it showed a trend of decline.4.The thawing frozen semen vitality in spring and autumn were significantly higher than it in summer and winter. It was the worst summer(P < 0.01). Individual differences in spring and autumn is not significant(P > 0.05), but individual vitality differences in the summer had significant difference(P < 0.05).5.Bull semen density of summer and spring, autumn is extremely significantly different(P<0.01), significant difference was found in the summer and winter(P < 0.05), suggesting the hot summer can make bull semen density decreased, and the impact will be better in autumn. In winter, bull thawing frozen semen vitality will significantly decreased. At the same time, there are apparent difference among the individual bull semen densities. There are significant differences between the hot summer months on bull semen density also have certain difference, the bull with usually good semen density are more easily affected by seasons.6.Bull frozen sperm deformity rate: bull frozen sperm deformity rate in summer is obviously higher than in spring, autumn and winter(P < 0.01). Bull frozen sperm deformity rate in winter is significantly lower(P < 0.01) than in summer, but it is still as high as 15.24%. At the same time, differences also exist between different individuals(P < 0.05).7.Bull frozen semen acrosome intact rate: bull frozen sperm acrosome intact rate in hot summer is significantly lower than in spring and autumn(P < 0.01), and significantly lower than in winter(P < 0.05), although acrosome intact rate in winter is higher than the summer(P < 0.05), but not back to the spring and autumn levels. The second part:Diet containing trace elements of organic zinc and organic coppor is fed to bulls for three months, the bull semen quality is not significant difference between the test group and the control group. |
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