In ejaculates, viable spermatozoa of normal morphology are sometimes a very low percentage of the total cell population. This Application Sheet presents a detailed protocol for the recovery of a highly viable fraction of bovine spermatozoa for use in fertilization. The recommended strategy involves, in the first instance, adjustment of the density of a semen sample to approx. 1.17 g/ml. 

Ideally, two lower density solutions are then layered on top, so that the viable semen of normal morphology band at the interface between theses two layers. 

These cells are thus completely separated from both the non-viable cells (and any soluble material released from partially broken cells), which all remain in the load zone, and any morphologically abnormal cells that band at the top of the least dense layer. This result is depicted in Figure 1.