Abstract
This study was designed to evaluate the ability of ram spermatozoa (thawed or thawed swim-up selected) to bind to homologous oocytes subjected to different treatments (in vitro matured or immature, fresh or vitrified). Frozen semen from Guirra breed males was tested on 1,267 oocytes harvested from pre-pubertal ewes at an abattoir. Highest proportions of oocytes with bound spermatozoa were recorded when in vitro matured oocytes, whether fresh or vitrified, were coincubated with thawed spermatozoa separated by swim-up (60.8 and 56.8% for fresh and vitrified matured oocytes, versus 9.4 and 11.1% for fresh and vitrified immature oocytes, respectively, p < 0.05). The number of bound spermatozoa per oocyte was also significantly higher for the swim-up selected spermatozoa than the thawed untreated spermatozoa (3.2 +/- 0.5 vs 1.6 +/- 0.7, p < 0.05, respectively), and higher still when fresh in vitro matured oocytes were used (8.3 +/- 0.5).
Highlights
The Guirra (Sudat or Roja Levantina) sheep is the only ovine breed autochthonous to the Comunidad Valenciana, its current census being 3,640 females and 174 males
According to the FAO catalogue and Royal Decree 1682/97 (BOE, 1997), this breed is in danger of extinction and its recent decline has prompted a conservation program based on genetic resources which, among other measures, includes the creation of a semen bank
Detecting reduced-fertility males can be simple since these animals often show signs of altered semen quality that can be detected by routine analyses
Summary
The Guirra (Sudat or Roja Levantina) sheep is the only ovine breed autochthonous to the Comunidad Valenciana, its current census being 3,640 females and 174 males. According to the FAO catalogue and Royal Decree 1682/97 (BOE, 1997), this breed is in danger of extinction and its recent decline has prompted a conservation program based on genetic resources which, among other measures, includes the creation of a semen bank. Detecting reduced-fertility males can be simple since these animals often show signs of altered semen quality that can be detected by routine analyses. Not all the ejaculates showing adequate quality indicators are of normal fertility. The factors most commonly used to evaluate sperm quality in semen samples are sperm motility and morphology. Developed image analysis programs (computer assisted sperm analyser, CASA) provide an objective estimate of the number of motile spermatozoa in the ejaculate, their quality of movement and can even be used to correlate morpho-
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