Cryopreservation of rabbit semen using non-permeable cryoprotectants: effectiveness of different concentrations of low-density lipoproteins (LDL) from egg yolk versus egg yolk or sucrose.

for the cryopreservation of rabbit semen by comparing the effects of different concentra-tions of low-density lipoproteins (LDL) on post-thaw sperm quality with those of whole eggyolk or sucrose. In a second experiment, the performance of the non-permeable CPAs iden-tified as most effective was assessed in vivo by determining reproductive performances.Pooled semen samples were diluted to a ratio of 1:1 (v:v) in freezing extender (Tris-citrate-glucose and 16% dimethylsulfoxide as permeable CPA) containing as non-permeable CPAs6, 8, 10 or 15% LDL from egg yolk, 0.1 M sucrose, or 15% egg yolk. The semen was loaded in0.25 mL straws and frozen in liquid nitrogen vapor. After thawing, we determined spermmotility, viability, osmotic resistance, and acrosome and DNA integrity. Our results clearlyrevealed a significant effect of LDL concentration on semen quality. Also, at an optimal con-centration of 10%, motility and acrosome integrity were improved over the values recordedfor egg yolk (P < 0.05). Based on the in vitro data, 3 groups of does (n = 30 each) wereinseminated with fresh semen or semen frozen using sucrose or 10% LDL. Sucrose led to asignificantly higher conception rate than LDL and reproductive performance was similar tothat observed for fresh semen. Our findings indicate the markedly better performance ofsucrose in vivo as a non-permeable CPA for the cryopreservation of rabbit semen.© 2014 Elsevier B.V. All rights reserved.