The use of a hypo-osmotic swelling (HOS) test on sperm of the pig (Sus scrofa domesticus), emu (Dromaius novaehollandiae), Asian elephant (Elephas maximus), hamadryas baboon (Papio hamadryas hamadryas), and central rock rat (Zyzomys pedunculatus).

A hypo-osmotic swelling test using TALP-HEPES medium over a range of 50 to 300 mOsm/kg was applied to sperm from domestic and endangered species. Maximal responses of curling of the sperm tails were seen over a range of osmolalities for epididymal sperm from the pig (100 mOsm/kg), hamadryas baboon (range 50-125 mOsm/kg), and central rock rat (range 50-100 mOsm/kg), and the ejaculated sperm from the emu (50 mOsm/kg) and the Asian elephant (range 75-150 mOsm/kg). A solution of TALP-HEPES medium at 100 mOsm/kg would be suitable to obtain the maximal response in this range of mammals tested, though it would need to be diluted to at least 50 mOsm/kg when testing the viability of the emu sperm.