Improvement on the efficiency of doses per conception by using a semen extender in timed artificial insemination

Abstract This study evaluated the efficiency of a post-thaw diluent on the conception rate of timed artificial insemination (TAI), on the in vitro embryo production (IVEP), the fertilization rate and the computerized semen analysis. In the execution of all the techniques, semen straws of a single bull with previously known fertility were evaluated both as control and extender groups. The conception rate was similar ( P  = 0.517) between the extender (52.11%) and the control group (55.48%), but the extender group showed a reduction ( P vs. 1.80 for the control). We evaluated the rates of cleavage (81.56 vs. 78.52%), blastocyst formation (36.10 vs. 39.48%) and hatching (47.28 vs. 41.97%) on the IVEP and assessed the fertilization rate by counting pronuclei (61.76 vs. 65.22%). Importantly, we found that these measures did not differ ( P  > 0.05) between the extender and control group, respectively. The total (58.1 vs. 58.3%) and progressive (42.4 vs. 40.0%) motility post-thawing did not differ ( P  > 0.05) between the extender vs. the control group, respectively. However, when comparing different moments post-thawing (0 h, 10 min, 3 h, 6 h, 8 h e 12 h), initially (3 h) the extender group had a higher ( P vs. 48.0%). Subsequently (8 h), the motility decreased ( P vs. 22.6%). In conclusion, the use of extender post-thawing was effective in TAI, reducing the number of doses per conception but not influencing the IVEP. Therefore, this extender allowed for the more efficient use of semen of high genetic value, reducing the cost per pregnancy.