Capacitation and Acrosomal Reaction Parameters of Fresh and Cryopreserved Rooster Semen

Background: Semen cryopreservation induces alterations in spermatozoa and changes in the plasma membrane, limiting the acrosome reaction and fertilizing ability. The research aim was to study the sperm capacitation indicators and acrosome reaction capacity in rooster semen, comparing fresh semen and post-thaw semen. Methods: Fifty ejaculates were obtained from five roosters through dorsal-ventral massage. Semen was diluted and preserved fresh or cryopreserved in Beltsville Poultry Semen Extender. In both groups of preserved semen, basic seminal parameters, capacitation and acrosome reaction were assessed. The latter were evaluated both with and without a perivitelline layer as the acrosome reaction inducer, using chlortetracycline staining. Result: The results revealed a higher percentage of sperm progressive motility in fresh semen (85.2±1.5%) compared with thawed semen (44.8±1.7%; P less than 0.05). The percentages were similar when comparing sperm with an acrosome reaction in fresh semen (10.6±1.1%) to sperm incubated without a perivitelline layer (13.2±1.7%; P greater than 0.05). However, when incubated with a perivitelline layer for 40 minutes, fresh semen spermatozoa exhibited a higher percentage of acrosome reaction (59.2±2.1%) compared with thawed semen incubated with a perivitelline layer (40.6±2.3%; P less than 0.05).