14 MORPHOLOGICAL AND FUNCTIONAL PARAMETERS OF ENDANGERED BERMEYA GOAT BREED SEMEN

Abstract

The Bermeya goats are an endangered autochthonous breed distributed in the north of Spain. To ensure their genetic diversity and long-term survival, morphological and functional parameters of the semen must be known in order to preserve the current genetic stock in a germplasm bank. The aim of this work was to establish basic characteristics and post-thaw survival of Bermeya goat's semen obtained by electro-ejaculation, that is not well described in the literature. The semen was collected by electro-ejaculation from 7 bucks, 1 to 7 years old, twice per week, for 9 weeks (n = 83). Fresh semen was evaluated for volume (V), concentration (C), motility, morphology, functional integrity of the sperm (spz) membranes (hypoosmotic swelling test; HOST), and acrosome integrity rate (NAR). Individual and progressive sperm motility were analyzed by means of a computer-assisted sperm analysis system (CASA: SCA 2002^®, Microptic, Barcelona, Spain) immediately after dilution with the extender at 37°C, and after cooling to 4°C; five fields per sample (diluted to 204 × 10⁶ spz mL^–1) were evaluated under a phase contrast microscope (100×). The NAR and morphological abnormalities of sperm head, midpiece, tail, and cytoplasmic droplets were determined by counting 100 spz under 1000×. For freezing, ejaculates with at least 80% motile spz were diluted at 32°C with Krebs-Ringer solution containing 20% egg yolk and 14% glycerol to a final concentration of 400 × 10⁶ spz mL^–1, cooled to 4°C for 90 min, aspirated into 0.25-mL plastic straws (IMV^®, L'Aigle, France), frozen at 7 cm above liquid nitrogen (LN₂) phase for 10 min, and then plunged into the LN₂. Straws were thawed in a water bath at 39°C for 30 s for post-thaw survival analysis. Data were analyzed by the GLM and FREQ procedures (SAS; SAS Institute, Inc., Cary, NC, USA) and expressed as means ± standard error. Fresh semen characteristics were: V = 1.7 ± 0.1 mL; C = 2619 × 106 ± 153 spz mL^–1; total and progressive motility were 89.0 ± 2.1% and 66.9 ± 2.1%, respectively. Percentages of head abnormalities were 4.8 ± 0.5; midpiece: 3.8 ± 0.7; tail: 4.7 ± 1.0; cytoplasmic droplets: 8.3 ± 0.7; intact acrosome: 91.8 ± 0.6; and membrane integrity: 49.2 ± 2.1. At 4°C, the % of total motile spz was 62.6 ± 1.6, and the post-thaw survival rate was 46.3 ± 1.5. There were only individual differences (P < 0.001) between bucks on sperm concentration, head abnormalities, and cytoplasmic droplets. In conclusion, our results indicate that semen quality is related to each individual animal and that electro-ejaculation allows collection of semen of satisfactory quality to use as fresh and for cryopreservation. However, the validity of our results for possible future sperm banking of endangered Bermeya goats semen must be confirmed by field trials.