COMPARISON OF 2 PROCESSING SYSTEMS FOR BULL SEMEN WITH REGARD TO POSTTHAW MOTILITY AND NONRETURN RATES

Two semen processing systems based on either skim milk-yolk extender o r Biladyl(R) were compared with regard to post-thaw motility and nonre turn rates. The skim milk-yolk extender contained penicillin and strep tomycin, while Biladyl(R) consisted of tylosin, gentamycin, spectinomy cin and lincomycin. The dilution of semen involved a 2-step procedure for both extenders. The second dilution with the skim milk-yolk extend er took place at 5 degrees C, while the Biladyl(R) extender was proces sed at room temperature. In this study 197 ejaculates from 45 Norwegia n Cattle bulls were used. The ejaculates were split-sampled and dilute d with the 2 extenders. A total of 41,445 first inseminations was reco rded, 21,035 with semen diluted with skim milk-yolk and 20,410 with Bi ladyl(R). The 60-d nonreturn rates were 73.1 and 71.9% for skim milk-y olk and Biladyl(R), respectively. The results for skim milk-yolk were significantly better than for Biladyl(R) (P<0.01). No difference in po st-thaw motility for these extenders was found.