PSII-20 Effect of mixing of extended boar semen using a bulk semen delivery system after 2 and 5 days in storage

With the increase in utilization of bulk semen delivery systems, the objective of this study was to determine whether differences in semen quality exist from mixing stored bulk semen. Semen with motility and normal morphology >75% were used to create 4, 70-dose and 4, 35-dose bulk semen bags. Semen was cooled and transported 235 miles. On d2 or d5, a bag was mixed and hung for 15 min. Doses were removed every 2 minutes. One 70-dose (70M) and one 35-dose bag (35M) were mixed every 5th dose, while the remaining 70-dose (70NM) and 35-dose (35NM) bags were not mixed. Doses were weighed and analyzed for concentration using CASA and agglutination assessed. Every 5th dose was warmed and evaluated for motility. One milliliter of semen from the 5th dose was preserved and evaluated for sperm cell morphology. Doses averaged 0.04 ± 0.0001 x 109/mL cells in 31.5 ± 0.077 mL resulting in 1.26 billion sperm/dose. All bags averaged >80% motility on d2 and 69% on d5 with >90% normal morphology on both days. There were minor differences in concentration and normal morphology from variation in preparing bags, not associated with mixing. On d2, mixing had no significant effects on agglutination or motility (P > 0.05). Concentration differed between 35M and 35NM (0.0385 ± 0.0004 vs 0.0417 ± 0.0002 x 109/mL; P < 0.001), with no identifiable trend. On d5, mixing had no effects on concentration, normal morphology or agglutination (P > 0.05). Bag 70M had more distal droplets compared with 70NM (3.78 ± 0.31 vs 2.36 ± 0.34%; P = 0.023). There was a non-significant linear decrease in concentration in the 70NM and 35NM bags, where concentration decreased by 0.124 x109 cells. Mixing alleviated this reduction in the 35-dose bags and partially alleviated it in the 70-dose bags. These data demonstrate that mixing had minimal impact on semen quality and was able to mitigate the decrease in concentration in the 35-dose bag.