RESUMO
The aims of this study were to determine the reproductive seasonality of four captive markhor goats (Capra falconeri heptneri), to characterize semen collected by electroejaculation, and to compare extenders and processing techniques for semen cryopreservation. Over the course of 1 yr, mean monthly scrotal circumference, serum testosterone, and fecal testosterone were measured and found to be inversely associated with day length. Maximum scrotal circumference (25.2 +/- 0.9 cm), serum testosterone (521.0 +/- 103.4 ng/dl), and fecal testosterone (382.5 +/- 90.3 ng/g) occurred in November, when day length was short (9.7 +/- 0.1 hr). Once a month for 3 mo (December, January, and February), bucks were anesthetized for electroejaculation and semen evaluation. Semen samples were divided into six aliquots for extension and cryopreservation in soy-based Bioxcell or Tris-based extender with 5 or 15% egg yolk, with and without centrifugation. Samples were then thawed for repeat evaluation 1-3 mo later. Postthaw evaluation revealed no significant differences between centrifuged and noncentrifuged samples. Sperm in Tris 5% and 15% egg yolk displayed higher total motility at 0, 3, and 6 hr postthaw and higher progressive motility postthaw compared with sperm in Bioxcell (P < 0.05). Sperm in Bioxcell displayed higher viability than sperm in both Tris-egg yolk extenders (P < 0.01), more intact acrosomes than sperm in Tris-15% egg yolk (P < 0.05), and a tendency for more intact acrosomes than sperm in Tris-5% egg yolk (P < 0.10). Sperm in Tris-5% egg yolk tended to have a higher percentage of morphologically normal sperm compared with Bioxcell (P < 0.10). This study provides evidence that markhor goats exhibit seasonality in scrotal circumference and testosterone levels and that centrifugation may be eliminated from the processing of markhor semen.
