Effect of warmed semen extender on boar sperm quality post-collection

Semen used for artificial insemination (AI) in the swine industry is typically collected into a warmed semen collection cup containing an empty collection bag. If the ambient temperature does not closely match the temperature of the warmed collection cup and semen at the time of collection then negative effects to the motility and morphology of the sperm cells may occur due to temperature shock. The purpose of this research was to determine if collecting boar semen directly into semen extender warmed to 38.5°C would affect sperm quality post-collection. Sexually mature Berkshire x Duroc crossbred boars (n = 7) were semen collected once per week for four consecutive weeks. Every other collection, the boar's ejaculate was collected into a collection cup and plastic collection bag warmed to 38.5°C containing either no semen extender (control) or 100 mLs of a commercially available long-term semen extender warmed to 38.5°C (treatment). Following collection and processing, the semen was extended to 37.5 × 106 sperm/mL and stored for 6 days post-collection in a semen cooler at 17°C. Motility and morphology were evaluated on day 0 (day of collection) and day 6. There was no day x treatment effect (P > 0.05). Statistical differences (P = 0.03) were found between the treatment and control for sperm motility (82.2 vs. 75.2%) and sperm progressive motility (64.1 vs. 53.5%). No differences (P = 0.96) were present for normal sperm morphology in the treatment compared to the control (89.1 vs. 89.0%). These data suggest that boar semen ejaculates collected into a collection cup and plastic collection bag containing 100 mLs of semen extender warmed to 38.5°C will have greater percentages of motile and progressively motile sperm compared to boar sperm collected into a collection cup and plastic collection bag warmed to 38.5°C containing no semen extender.