Breeding soundness examination, semen freezing and evaluation of frozen-thawed semen in native Omani bulls – preliminary study

Abstract

The present study was undertaken as part of a project on ‘Characterization, Evaluation and
Conservation of Indigenous Animal Genetic Resources in the Sultanate of Oman’. The objective of this
study was to conduct breeding soundness examinations (BSE) and determine the characteristics of frozenthawed
semen of native Omani bulls. Breeding soundness examinations were carried out in twelve bulls
age three to four years; six bulls were found to be satisfactory, while the remaining six were
unsatisfactory as potential breeders. Semen was collected using an electroejaculator (EE) in the six bulls
once per week for two consecutive weeks. The volume of the ejaculates and the initial sperm
concentration were measured. Nine ejaculates were qualified for freezing. Semen was diluted in tris egg
yolk extender and frozen in liquid nitrogen vapor. Frozen semen straws were thawed at 37°C for at least
30 seconds in a water bath for assessment of post-thaw semen quality. The mean volume of semen and
sperm concentration was 9.08 ± 0.9 ml and 284.6 ± 24.8 X 106/ml, respectively. The post-thaw total
sperm motility was 64.6 ± 5.2% and progressive motility was 34.2 ± 4.1%, as evaluated by computer
assisted sperm analysis. The hypo-osmatic swelling test positive spermatozoa was 27.1 ± 3.5%, intact
acrosome was 90.7 ± 1.41% and sperm abnormalities were 8.3 ± 1.0% in post-thawed semen. Overall,
the quality of the post-thawed semen in the present study was similar to that obtained from crossbred and
exotic bulls. In conclusion, BSE was beneficial in bull selection, semen was collected successfully using
an EE and frozen in native Omani bulls. The frozen-thawed semen was suitable for artificial
insemination procedures.