Supplement 1) Peer-reviewed paper

Abstract Maintaining a successful pig artificial insemination programme depends on a number of factors, including evaluation of semen characteristics. This study compared the efficacy of different extenders on the sperm motility of Kolbroek semen during short term storage at 4 °C and 25 °C. Semen was collected from Kolbroek boars using the gloved hand technique and transported to the laboratory for evaluation. Semen was pooled and randomly allocated to four groups and diluted at a ratio of 1:1 (v/v) with Beltsville thawing solution (BTS), Kobidil + , egg yolk citrate (EYC) and non-extended semen (Control). Each extender had two similar semen samples, making a total of eight samples. Extended and non-extended semen were stored at 4 °C and the other samples at 25 °C for 1 h. Data were analyzed using analysis of variance (ANOVA). The total sperm motility of semen stored at 25 °C was higher when semen was extended with BTS and Kobidil + in comparison to the egg yolk citrate diluent. However, total sperm motility in the non-extended semen did not differ from the BTS and EYC group during storage at 25 °C. Sperm progressive motility was higher in the BTS group, compared to the Kobidil + and non-extended groups. Sperm motility of Kolbroek semen at 4 °C did not differ between all extender treatments. Total motility rate was significantly higher when Kolbroek sperm were stored at 25 °C than at 4 °C. It can be concluded that Kolbroek sperm, extended with BTS, maintained their motility rate better for short term storage at 25 °C in comparison to 4 °C. ______________________________________________________________________________________