that sperm production and sperm Mot of ejaculated
spermatozoa in swamp buffaloes in Thailand are not
affected by season [11,49]. However, PMI (assessed by
a hypo-osmotic test of a few spermatozoa per sample)
showed some relation to seasonality [9]. Whether such
seasonal effects also appear in cryopreserved spermatozoa
at different moments of the year and in different
years remains to be explored using methods that allow
higher objectivity and the screening of larger sperm
numbers.
In the present study, we hypothesized that seasonality
influences post-thaw viability (in terms of PMI,
PMS and Mot) of frozen-thawed swamp buffalo AI
spermatozoa processed under conditions of tropical
Thailand. Flow cytometry of SYBR-14/PI and
Annexin-V/PI-loaded spermatozoa as well as CASA
were the methods used to increase the objectivity and
details of the analyses. Moreover, a thermal resistance
test (38 8C for 60 min) was used to further analyze the
potential of the spermatozoa to survive in vitro.