Semen Processing - Centrifugation

Some ejaculates are not concentrated enough to dilute 1:3 and have a breeding dose of less than 50 ml (ejaculates with less than 80 million sperm per ml ). In these cases, if the motility is good (at least 50%), the ejaculate can be concentrated by centrifugation. This technique is described below and also appears on the Cooled Semen Preparation handout.

Put 20 ml of clear centrifugation buffer in a 50 ml centrifuge tubes and place in water bath at 37 – 39°C. You will be adding 20 - 25 ml semen to the tube so put sufficient tubes in for the normal size ejaculate of the stallion you are collecting.

Put 0.5 ml aliquots of cushion solution in a 12 X 55 tubes (image to the right) and place in water bath to warm to 37°C. The cushion will be used so the sperm are not damaged by packing too hard during centrifugation. Cushions are commercially available ready-made or can be made with Percol (silicone beads that are commercially available) but are very expensive (image below). We aliquot the cushion buffer so that we do not contaminate the entire bottle.