Effect of diluition at collection or 24 h after on boar semen quality and lipid composition variation during storage

This study considered if it would be better commercial practice to dilute boar semen 24 hours after collection. Samples were diluted in BTS either after collection (T0) or after a 24 hour storage period (T24) at 18°C, subsequently the semen was stored at 18°C. On days 0, 1, 2, 3, 4 and 5 of incubation, sperm quality parameters, i.e. proportion of motile cells, score for forward progression, normal acrosome region (NAR) and proportion of damaged cells were measured. While lipid analysis were carried out solely on days 0, 3 and 5 on both sperm cells and seminal plasma. The proportion of motile sperm decreased significantly between day 0 (78.9%) and day 3 (72.7%) and furtherly between day 3 and 5 (62.9%) for semen diluted at T0 while this proportion did not decrease significantly for the T24 group. For all other sperm quality parameters, there was no significant effect of the time of dilution. Quality of motility decreased throughout incubation with a proportion of motile cells being rated between 2-4 decreasing significantly from 58.6 to 52.6 %. The proportion of damaged spermatozoa increased significantly from day 0 (8.9 %) to day 2 (12.2%), between day 2 and 3 (13.5%) and day 3 and 4 (14.9%). NAR decreased significantly throughout incubation from 79.9% on day 0 to 74.7% on day 5. The fatty acid content of spermatozoa did not change significantly during incubation, with about 35 % of docosahexaenoic acid and 29 % of docosapentaenoic acid.