For artificial insemination (AI) in pigs, preservation of liquid boar semen at
16–20 °C is still common practice as sperm cryopreservation remains suboptimal
in this species. To meet the different needs of the swine industry, several
extenders have been developed to preserve semen in liquid form for short- and
long-term storage. In the present study, three different commercial extenders
devised for short-term (BTS+) or long-term preservation (MR-A and X-Cell),
were used to test whether storage of semen from four mature, fertile boars at
17 C for 96 h would affect sperm characteristics relevant for fertility, such as
motility, membrane integrity and chromatin stability. Computer-assisted sperm
analysis, and stainings with the acylated membrane dye SYBR-14/propidium
iodide, and acridine orange in connection with flow cytometry were used to
evaluate these variables. Percentages of total motile spermatozoa decreased
slightly, but significantly, after 72–96 h. While membrane integrity values varied
during the period of study, no significant changes in either membrane
integrity or chromatin stability were, however, registered. This suggests a customary
96-day storage at 17 °C in these extenders was too short an interval to
cause losses of integrity in nuclear DNA in the boar population studied.