Glycine betaine improves survival of fresh bovine spermatozoa

Fresh spermatozoa from bulls established as 'good freezers' and 'poor freez ers' (consistently :greater than or equal to 50% or < 20% motile spermatozo a after cryopreservation, respectively) were incubated for 96 h in Tes/Tris -egg yolk or TALP-egg yolk media at 37 degrees, 20 degrees, 5 degrees or 0 degreesC. The TALP extender contained 0, 100 or 200 mm glycine betaine (GB) to test the hypothesis that GB would efficiently maintain spermatozoa func tion during long-term incubation. The percentage of motile spermatozoa decl ined over time in a temperature- and medium-dependent fashion. No spermatoz oa were motile by 24 h incubation at 37 degreesC or by 72 h incubation at 0 degreesC, and there were no significant differences in the percentage of m otile spermatozoa from either category of bull when spermatozoa were incuba ted in any media for less than 24 h. Spermatozoa from poor freezers were si gnificantly more motile than spermatozoa from good freezers after 96 h at 2 0 degrees or 5 degreesC in TALP alone; however, GB at both 100 and 200 mm i ncreased the percentage of motile spermatozoa in poor and good freezers and eliminated these differences. Overall, the presence of GB at either 100 or 200 mm significantly improved the percentage of motile spermatozoa at 20 d egrees, 5 degrees and 0 degreesC, but not at 37 degreesC.