An Evaluation of Effect of Two Extenders and Storage Temperature on Quality of Alpine Goat Semen Processed With and Without Seminal Plasma

Abstract

This study was designed to evaluate the quality of semen of Alpine goats extended in OptixcellTM ((OPT), a commercially available semen extender) and coconut water based eggyolk- containing extender (COC) with and without seminal plasma and stored under three different temperature conditions. COC was a newly formulated extender whose capability to maintain viability of goat semen was test against the commercially available OPT. Semen samples were stored either at room temperature as RT semen, chilled (CH semen), or deepfrozen in liquid nitrogen (DF semen). Viability of semen was determined using two parameters; percentage individual progressive motility of spermatozoa and percentage live spermatozoa. Ejaculates were collected from bucks using artificial vagina. Each ejaculate from each buck was split into two portions. One portion was left intact whereas the other portion was centrifuged to remove seminal plasma. The pellet obtained after centrifugation was reconstituted to the initial volume (before centrifugation) using normal saline. Each of the two parts was further divided into two equal portions for extension with each extender. Extended semen samples were stored at room temperature (21-230C), chilled (1-40C) and deep-frozen in liquid nitrogen (-1960C). Semen viability of the processed samples stored at room temperature and chilled was evaluated daily until zero values were recorded. Deepfrozen samples were examined for spermatozoa viability only once after 120 days of storage in liquid nitrogen. The results showed that addition of either extender to goat semen was not detrimental to the spermatozoa in semen samples with or without seminal plasma. However, motility was significantly reduced within two hours following extension, in both samples with and without

seminal plasma (p<0.05). Each extender did not have any significant effect on percentage live spermatozoa with seminal plasma (p>0.05), but a significant drop in percentage live spermatozoa was observed in samples where seminal plasma was removed (p<0.05). There was no significant difference in the longevity of spermatozoa between the two extenders with and without seminal plasma when semen samples were stored at room temperature and chilled (p>0.05). The results further showed that removal of seminal plasma prolonged the shelf life of spermatozoa in each extender (p<0.05). At 50% motility cut-off, semen extended in OPT and stored at room temperature maintained viability for only 3 days with seminal plasma. However, when seminal plasma was removed it performed better (5 days) similar to COC with and without seminal plasma. Semen samples stored chilled with or without seminal plasma maintained motility above 50% for at least six days in both extenders. However, three additional days were recorded when semen was extended in OPT with seminal plasma removed. Deep-frozen semen samples extended in OPT recorded mean post-thaw viability values above 50% at 120 days while those extended in COC were all dead. From the findings of this study, both extenders could be used in processing goat semen intended for room temperature and chilled semen use with or without seminal plasma. However, only OPT and not COC would be used to extend semen for deep freezing. Semen extended in COC maintained usable viability for the same duration (5 days) when stored at room temperature with and without seminal plasma. For chilled semen, the difference in duration with and without seminal plasma was also minimal (6 and 7 days). Therefore, it would not be necessary to remove seminal plasma from goat semen to be extended in COC, for artificial insemination, if such semen was to be used as room temperature or chilled at 1-

40C. However, removal of seminal plasma favoured greatly the longevity of usable viability of spermatozoa for both room temperature and chilled semen when extended in OPT.