Effects Of Mixing Prior To Automated Packaging In Extended Boar Semen

Abstract It is known that sperm cells will settle out of extender over time which could impact the concentration per dose within a batch. The objective of this study to investigate the effects of mixing prior to packaging on concentration of packaged insemination doses. At a commercial boar stud, three ejaculates were collected, extended, pooled and assigned to one of three treatment groups: pour-mix (PM) where ejaculates were immediately packaged after combining the three ejaculates, stir-mix (SM) where three ejaculates were combined and stirred thoroughly then packaged, or no mixing (NM) where pooled ejaculates were allowed to sit for 10 min then packaged. Semen was packaged with 35ml per tube creating ~350 individual doses of semen. Every fifth dose was labeled with consecutive numbers (~70/treatment) and overnighted to Purdue University. Concentration of each dose was determined using the NucleoCounter® SP-100TM. The entire study was repeated over 6 weeks. Within treatment, concentration did not differ among doses for the PM and SM treatments. However, NM doses were less concentrated (P< 0.001) in doses >300 compared to all others and doses 251–300 were less concentrated than doses 1 to 50. NM samples 1–250 averaged 36.12 million cells/ml whereas samples 251 to the end of the batch averaged 34.68 million/ml. This results in the last 20 doses having ~50.4 million less cells/dose. Across treatments, NM had lower concentrations (P=0.02) from doses >200 compared to the SM treatment. PM appeared to be an intermediate as it was numerically lower than SM, but not statistically different from either NM or SM. The difference in concentrations between the NM and SM >200 was 1.85 million/ml equaling 64.75 million fewer cells. Overall, allowing semen to settle and not mixing prior to packaging can result in 50–64 million cells fewer per dose in the last 50–100 doses packaged.