Characteristics of fresh and frozen-thawed Uda ram semen extended with Oviplus®, egg yolk and coconut milk

Abstract

Semen characteristics of Uda sheep and the effects of the egg yolk and coconut milk-based extenders on the quality of semen preserved at 4 oC and -196 oC were evaluated. Semen was collected from six Uda rams using an electro-ejaculator twice a week for ten weeks. Fresh semen samples were pooled and analyzed macroscopically and microscopically. The pooled semen was divided into 2 aliquots. One aliquot was extended in OviPlus® and egg yolk. The second aliquot was extended with OviPlus® and coconut milk. Each of the aliquots was further subdivided into 2 parts and evaluated microscopically. One part was chilled at 4 oC and evaluated for the same parameters after extension at 24, 48 and 72 hours. Second part was loaded into 0.25 ml plastic straws for cryopreservation at -196 ℃ and analyzed after 24 hours. The post thaw spermatozoa motility, livability and morphological abnormalities were determined at 24, 48 and 72 hours. The motility and concentration of freshly collected Uda semen were 81.7 ± 1.7 % and 3.2 ± 0.3 ×109/ml respectively. After extension, the motility decreased significantly (P < 0.05) from 82 % at 3 hours to 17 % at 72. The percentage live spermatozoa of the chilled semen did not differ significantly (P > 0.05) between the two extenders. Post thaw spermatozoa motility and livability were significantly (P < 0.05) reduced. There were significant differences (P < 0.05) between the post-thaw proportions of morphological abnormalities, between semen preserved at 4 oC and the frozen-thawed semen. In conclusion, semen motility, livability, and morphological abnormalities of Uda ram are equally preserved in coconut milk and egg yolk-based extenders at 4 oC up to 24 hours post extension. However, semen motility and livability were significantly reduced in the Uda semen earlier cryopreserved at -196 oC after thawing.