Functional assessment of diluent choice for semen cryopreservation from stallions with high and low freezability

ABSTRACT

Background: Fertility using horse frozen-thawed semen remains lower than in other livestock species. This fact suggeststhat horse semen hold intrinsic sensitivity to cryoinjury that must be investigated. Moreover, there is substantial evidenceof genetic factors upon horse cryopreservation outcome. Nonetheless, diluent and cryoprotectant choice for horse semencryopreservation are under intense research. Thus these factors could be explored to identify conditions that may increasesemen viability after thawing. The aim of this work was to evaluate the effect of diluents Botu-Crio®,Lactose-EDTA®, andINRA-82® on cryopreserved semen from stallions with high (HFA) and low freezability (LFA).Materials, Methods & Results: Frozen-thawed semen was evaluated for motility and membrane integrity using computerassisted semen analysis (CASA), and also inferred for sperm DNA fragmentation by sperm chromatin structure assay during the thermoresistance test (TRT). Comparisons for each parameter were done in a pair-wise fashion between HFA andLFA semen at one-hour intervals during the TRT (0 h - 4 h). Sperm motility in HFA, regardless of the diluent, was larger(P < 0.05) than LFA, both on 0h and 1h. In the 2h evaluation, sperm motility using Botu-Crio® and Lactose-EDTA® wasgreater (P < 0.05) for HFA. Analysis of sperm membrane integrity was similar between HFA and LFA semen (P > 0.05)at 0 h and 3 h. Sperm DNA fragmentation was lower (P < 0.05) in HFA semen at 0 h and 1 h.Discussion: Artificial insemination in horses using frozen-thawed semen is gaining wider acceptance under commercialsettings, although its current limited outreach due to low semen viability after thawing. Therefore, several efforts weremade toward ... (AU)