Supplemented stallion seminal plasma can improve impaired motility due to the dilution effect in chilled Asian elephant sperm

Contents The dilution effect and effect of restoring seminal plasma ( SP ) proportion in diluted semen were determined in chilled Asian elephant sperm. Semen was collected from eight males, and samples with ≥30% motile sperm were used in the study. Tris‐glucose‐egg yolk extender ( TE ) was used for cooled storage at 4°C for 48 hr. In experiment 1 ( n  = 18), semen was diluted to 1:1, 1:3, 1:7 and 1:15 with TE (volume per volume). There were no significant changes in sperm viability and sperm with normal acrosome integrity among dilutions, but sperm motility and motility velocities were greater ( p  < .05) in the 1:1 dilution than those of the 1:7 and 1:15 dilutions at 48 hr of storage. In experiment 2, supplemented SP was derived from elephants and stallions. In experiment 2.1, diluted semen (1:7 dilution) was restored with SP to obtain a 1:2 proportion ( n  = 8). Sperm motility, viability and sperm with normal acrosome integrity were similar among treatments, but motility velocities were greater ( p  < .05) with stallion SP at 48 hr of storage. In experiment 2.2, diluted semen (1:15 dilution) was restored with SP to obtain a 1:3 proportion ( n  = 10). Sperm viability and sperm with normal acrosome integrity were similar among treatments at 48 hr of storage. However, sperm motility and motility velocities were greater ( p  < .05) with stallion SP than those of others. In conclusion, elephant sperm motility was affected by a dilution effect and restoration of SP proportion with stallion SP , but not with elephant SP , could improve motility in chilled highly diluted sperm.