Use of low density lipoprotein in different concentrations in diluent medium for cryopreservation of ovine semen

ABSTRACT The use of egg yolk makes it difficult to standardize extenders and presents biological hazards. Thus, this study evaluated different concentrations of low-density lipoprotein (LDL) to replace yolk extenders for production of sperm for cryopreservation in ovine. A control extender was used (CTR= 20% yolk) and five treatments, replacing the yolk by different ratios of LDL (T1= 6%; T2= 8%, T3= 12%; T4= 16%; T5= 20%) all based on TRIS-glycerol. For the study, two ejaculates from six Santa Ines breeding were used. Sixty days after cryopreservation, the samples were thawed and evaluated for total motility (MT, %) and progressive motility (MP, %), vigor (1-5) and the functional integrity (hyposmotic shock with distilled water, %) and structural (supravital dye eosin, %) of the sperm membranes. The evaluations of strength and membrane functionality didn’t differ (P> 0.05) between groups. However, T4 (P< 0.01) and T5 (P< 0.05) groups were superior to the CTR for the MT, MP, and membrane structural integrity parameters, which confirms that LDLs can be efficient alternatives for yolk replacement in extenders for cryopreservation of ovine semen.