Use of boar spermatozoa for artificial insemination. III. Fecundity of boar spermatozoa stored in Beltsville liquid and Kiev extenders for three days at 18 C.
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A field trial was conducted on several hundred farms in The Netherlands to compare the fertilizing capacity of boar spermatozoa stored for 1, 2, or 3 d at 18 C in either Kiev or Beltsville liquid extender (BL-1). Two storage volumes (25 and 100 ml) were used. Twelve Dutch Landrace boars, all in routine commercial artificial insemination service, provided the semen in twice-a-week collections. Over an 8-wk period in March and April, 1979, 2,849 sows and gilts were inseminated. Farrowing rates were higher (P less than .0001) with Kiev extender than with BL-1 extender (69.3 vs 60.5%) when semen was used over a 3 d period. The volume at which the semen was extended and stored had no effect on any parameter. Farrowing rate declined significantly when semen stored at 18 C for more than 2 d was used (74.5% vs 64.7% with semen stored for 1 and 3 in Kiev extender; 65.9% vs 52.7% with semen stored for 1 and 3 d in BL-1 extender). The farrowing rate, total number of pigs/litter and live pigs/litter were significantly higher for sows than for gilts inseminated with similar extended semen. On the basis of the results of this trial, Kiev extender appears to be more suitable as a diluent for liquid semen than does BL-1. AI with semen extended and stored for 3 d at 18 C can be expected to result in a lower farrowing rate than AI with semen stored for 1 or 2 d.