Effects of Extenders and Glutamine on the Cooled Storage of Semen of Thai Native Crossbred and Full-Size Purebred Horses

Abstract

The effects of four different extenders on semen storage of Thai, native, crossbred (T; n = 5) and full-size, purebred (F; n = 4) horses were investigated. The extenders used were Kenney (E1), Kenney with 50 mM glutamine (E2), INRA-82Y (E3) and INRA-82Y with 50 mM glutamine (E4). The semen was collected through the use of an artificial vagina. It was then washed and the seminal plasma removed and maintained at 5°C in each extender for up to 96 h. The cooled samples were evaluated for viability using eosin-nigrosin staining and the hypo-osmotic swelling test (HOST) and then submitted to CASA for the analysis of total motility (TMOT), progressive motility (PMOT) and velocity parameters. It was found that there was a significant difference at (P<0.05) between T and F stallions for: the mean percentage of TMOT (77.8 %, 73.0 % ); PMOT (55.4 %, 46.8 % ); sperm concentration (309 × 10⁶ ml^-1, 374.5 × 10⁶ ml^-1); and osmolarity of fresh semen (329.3 mOsm, 314.6 mOsm). All the characteristics of the semen collected from the T and F stallions significantly decreased (P<0.05) after being stored for 24 h to 48 h in all extenders. The E3 tended to maintain sperm motility and membrane integrity for a longer period of time than the other extenders that were tested. Supplementing the extenders with 50 mM glutamine had adverse effects on the sperm motility and membrane integrity in cooled storage.