Semen storage at 23, 4 or -196°C and its application to artificial insemination in small-tail han sheep

Abstract

In order to provide more options to sheep artificial insemination (AI) technology this study evaluated the influence of preservation methods on sperm quality and subsequent fertility in Small-tail Hun sheep. For the following 1 treatments: Diluted fresh semen as a control, diluted semen stored at 4°C for 24, 48, 72, 96 or 120 h, Separate aliquots of diluted semen were stored at 23°C for 24 or 48 h and diluted semen stored at -196°C, The semen was evaluated for sperm viability, acrosomal integrity, mitochondrial function and capacitation status using Propidium Iodide (PI), fluoresceinated peanut lectin (FITC-PNA), 5,5',6,6'-tetrachloro-l,l',3,3'- tetraethylbenzimidazolyl-carbocya nine iodide (JC-1) and chlortetracycline staining, respectively. Proportions of spermatozoa showing high mitochondrial membrane potential and an incapacitated status were lower (p<0.05) in frozen semen than in samples stored at either 4°C for 72 h or at 23°C for 24 h. Sperm viability did not differ (p>0.05) among: Fresh semen, semen stored at 4°C for 48 h and semen stored at 23°C for 24 h. Following cervical insemination, semen stored at 4°C for 72 h or at 23°C for 24 h resulted in similar pregnancy rates (p>0.05) to those from fresh sperm (16/23, 69.6%, 19/25, 76.0% and 22/28, 78.6%), all of which were higher (p<0.05) than those from semen cryopreserved at -196°C (12/24, 50.0%). In conclusion, semen stored at either 4°C for 72 h or at 23°C for 24 h is structurally superior to semen cryopreserved at -196° C and achieved similar pregnancy rates as from AI using fresh semen. © 2012 Academic Journals Inc.