Effect of two animal protein-free extenders on cryopreservation of Pelibuey and Blackbelly ram semen

The study evaluated the effect of two animal protein-free extenders on ram semen cryopreservation of two tropical hair breeds. The ejaculates were collected from 8 rams (4 Blackbelly and 4 Pelibuey), which were mixed (pooled) by breed, diluted and cryopreserved in three different extenders: Animal protein [Tris egg yolk (Triladyl®)], and animal protein-free extenders AndroMed® (lecithin soy bean) and OPTIXcell® (liposome). Sperm analyses of total (TM) and progressive (PM) motility, viability, mitochondrial activity, acrosome integrity, and plasma membrane integrity (PMI) were carried out at 0 and 6 h after semen thawing. OPTIXcell® and Triladyl® extenders showed similar results between them and differed with AndroMed® in TM, PM, viability, and PMI (P<0.0017). In the Blackbelly breed, the TM was higher (P<0.0159) in OPTIXcell® than in AndroMed®. In the Pelibuey breed, the OPTIXcell® and Triladyl® showed similar results between them and differed with AndroMed® in TM, PM, viability, mitochondrial activity, and PMI (P<0.0140). However, Triladyl® showed a higher percentage of sperm with intact acrosome than AndroMed® (P<0.0392). In both breeds, spermatic parameters decreased progressively over the incubation time similarly in all three extenders. In conclusion, OPTIXcell® and Triladyl® proved to be the best extenders to cryopreserve Blackbelly and Pelibuey ram semen. However, OPTIXcell® is an animal protein-free extender that decreases the risk of bacterial contamination, whereas Triladyl® is composed of animal protein (egg yolk), which may impact the fertilizing capacity of sperm.