RESUMEN
BACKGROUND: Semen freezing is of great importance for animal production because it allows the use and the rapid diffusion of the genetic material from economically important animals. OBJECTIVE: To evaluate the effect of açai (Euterpe oleracea; Arecaceae family) extract addition to the semen cryopreservation diluent on the morphology, sperm motility parameters, and plasma membrane integrity of spermatozoa. MATERIALS AND METHODS: The ejaculates, obtained from five bulls with low performance on semen freezing, were fractionated and distributed according to the experimental group. The control samples did not have açaí extract added, whereas to the treated groups were added 5, 10, 15 or 20 mg ml-1 of açaí extract into the semen diluent. The sperm morphology was evaluated with a formalin-saline-buffered solution. The plasma membrane integrity was evaluated by the epifluorescent test, while the cellular kinetics was assessed by an automated analysis of the spermatic movement. RESULTS: The sperm defects showed a linearly decreasing effect (P < 0.05) with the addition of different concentrations of açaí extract. The plasma membrane integrity was higher (P < 0.05) after the açaí addition to the cryopreservation diluent. There was no significant effect (P > 0.05) of the açaí extract on the kinetics of spermatozoa. CONCLUSION: The addition of açaí extract to the cryopreservation diluent provided better preservation of the structural integrity of the sperm plasma membrane in the bull's semen with low tolerance to the cryopreservation process.