Influence Of Different Dilution Methods On Frozen Sperm Quality Of Holstein Bulls.

To utilize the herd sire with excellent genetic traits, in this study, 18 healthy and eroticized Holstein bulls from the sire farm of Centre of Prologue Elite of Hebei Province were randomly divided into 3 groups according to their ages. Their semen samples were diluted with three different methods before freezing. Method I: the semen was diluted by one step with 34℃diluent containing 7% glycerol; MethodⅡ: the semen was firstly diluted with 34℃diluent without glycerol, cooled down within 60min to 4～5℃, and then diluted by one step with 4℃diluent containing 14% glycerol; MethodⅢ: the semen was firstly diluted with 34℃diluent without glycerol, cooled down within 60min to 4～5℃, and then diluted gradually with 4℃diluent containing 14% glycerol. The livability, abnormality and perforatorium integrity rate of the semen were detected before and after freezing. The influence of different dilution methods to the semen was compared. The results indicated that the differences were not significant (p＞0.05) among three methods in the livability and abnormality rate, but the difference in perforatorium integrity rate was significant between the methodⅡorⅢand methodⅠ(p＜0.05) ; MethodⅢwas better than methodⅡ, but the difference was not significant (p＞0.05) .After freezing at -110~℃for 8min, the difference in perforatorium integrity rate was highly significant (p＞0.01) between the methodⅡand methodⅢ, and significant (p＞0.05) between the methodⅡand methodⅠorⅢ. The results showed that dilution methods of semen had influence in perforatorium integrity rate with the two-step dilution better than one-step dilution and slow dilution better than quick dilution.