Avaliação in vitro de espermatozoides da cauda do epidídimo de caprinos, resfriado a 4 ºc em diferentes diluidores

Collection of spermatozoa obtained from the epididymis cauda (CES) is a viable option to preserve of genetic material from threatened species and for use in assisted reproduction. The aim of the present study was to assess the in vitro effect of four different extenders on spermatozoa from goat epididymis cauda, cooled at 4 oC. Epididymal sperm were recovered from the cauda by flushing six pairs of epididymis. The samples of each pair were mixed, subdivided into four aliquots and diluted in coconut water-egg yolk (CW-EY), physiologic solution with 0.5 % glucose and egg yolk (PSG-EY), UHT skim milk (SM), and UHT skim milk with egg yolk (SM-EY). The samples were cooled at 4 oC for 2, 12, 24 and 48 hours. After storage, in each period, the semen was evaluated by the heat resistance test for sperm motility, vigor and total morphological alterations. The motility degradation rate was calculated at the end of each time period. Sperm viability decreased with time in the four extenders. Epididymal sperm diluted in CW-EY showed higher values for vigor and motility, although these parameters did not differ from the sperm kept in the PSG-EY up to 48 hours at 4 °C, except for spermatic vigor. However, the PSG-EY and SM extenders caused greater morphologic damage to epididymal sperm after 12 and 24 hours, respectively. Extenders based on skim milk provided less spermatic cell stability during 48 hours. In conclusion, CW-EY extender was the most efficient extender to maintain CES viability at 4 oC.