Native semen parameters of wild African elephant bulls collected during two consecutive years.

Letters next to the bull number indicate that the same bull was collected more than once either during the same year or in both years. Concentration relates to the utilized fraction and not to the total volume, which also included sperm-free or highly viscose portions that were discarded. Ages were estimated by the game reserve managers.
*Mean values were significantly different between the years for intact acrosome (P = 0.009) and normal morphology (P = 0.004).