Does anyone use an extender when performing a side by side AI (freshly collected)? Just curious.

If it were me, I wouldn't unless you need to increase the amount of volume of the collection, or to energize sluggish semen. Extender is known to give semen a burst of energy.

why would you need to?
the more fluids you put in the more back flow you will get washing out the semen.

I have heard of using the extender to flush the tube out instead of using air. Since air makes bubbles the sperm would attach to the air bubble.