Sperm production of the native Thai pony
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Thailand possesses a small population of native pony's. There's no studbook or any other kind of registration for this breed. There seemed to be some problems involving fertility according to local Thai people living in the provence of Khon Kaen. The study involved five adult native Thai stallions who were examined in the months January and February 2009. Total testicular volume and total testicular width were measured followed by assessment of two ejaculates gathered with an hour in between. Volume and concentration of the ejaculates were examined as well as the total sperm number (TSN) of the ejaculate, motility, vitality, morphology, total normal built moving sperm (TNM) and the sperm plasma membrane function by the HOS-test (hypo-osmotic swelling test). These parameters were compared with those of sires of Dutch Studbooks; Dutch Warmblood horse, Friesian horse, Welsh Pony and New Forest. Despite a relative big total testicular width and total scrotal volume of the native Thai pony, the average TSN (2425.50x10^6 SD:234.05x10^6) was significantly lower compared to the other breeds, as well as the average TNM (1234.37x10^6 SD:372.41x10^6). HOS-test outcome was 22.70% (SD:3.26%) HOS+, which is assumed to be very low, indicating a low sperm plasma membrane quality. This outcomes are indicative of a poor sperm production and quality of the native Thai pony. Since only five pony's are involved in this study, more research should be done to confirm this. Whether inbreeding and climate play a role in these results should be subject to near investigation.