The objective of this study was to investigate the effects of semen volume, air contact inside semen dose tubes, daily agitation of semen doses and extender type on semen quality, thermo-resistance and bacteria growth in extended boar semen doses preserved over 7 days of liquid storage. Ejaculates from 4 proven terminal cross-bred boars were collected using the gloved-hand technique for 4 weeks and used in the 3 × 2 × 2 factorial study. The effects of treatment (CON: 80 ml doses sealed at the top of the tube; 40HIGH: 40 ml doses sealed at top of tube, and 40LOW: 40 ml doses sealed at top of the liquid), agitation (agitated versus not agitated) and extender type (long-term versus short-term) were investigated on semen quality, thermo-resistance and bacteria growth in boar semen doses. The results of the study revealed that motility (p = .031) and viability (p = .041) in 40HIGH were lower than CON. pH (p < .001) was higher in 40HIGH compared with CON and 40LOW. Agitation did not impact motility (p = .581), progressive motility (p = .870), viability (p = .509) or morphology (p = .970), while long-term extender maintained higher motility (p = .002), progressive motility (p = .036), viability (p < .001) and normal acrosome (p < .001) than a short-term extender. VAP (p = .039) of 40HIGH was lower than CON in a thermo-resistance test. Neither treatment (p > .798, .766) nor agitation (p > .396, .476) impacted bacterial growth in this study. In conclusion, air contact negatively impacts boar semen pH and consequently sperm motility. Semen doses prepared with 80 or 40 ml volumes of extended boar semen with minimal air contact in the tubes yield more desirable semen quality and agitating boar semen doses daily does not have negative or positive effects on boar semen quality.
Keywords: agitation; air contact; bacteria; boar semen; semen quality; thermo-resistance.
© 2021 Wiley-VCH GmbH.