Effects of chelating calcium in cryopreservation extender on frozen-thawed dog semen

ABSTRACT We evaluated the effect of reducing free calcium in the cryopreservation medium, using the calcium chelator ethylene diamine tetracetic acid (EDTA) at 0.3% and 0.5% concentrations. Three male mixed breed dogs were subjected to semen collection by digital manipulation (n=16). Each ejaculate was divided in three aliquots, and each one was diluted in TRIS-glucose-egg yolk extender with 6% glycerol and 0.5% Equex STM Paste® (TGE, control); and added with 0.3% EDTA (EDTA 0.3) or 0.5% EDTA (EDTA 0.5). Calcium concentration reduced in EDTA 0.3 and all the calcium ions were chelated in EDTA 0.5. The EDTA addition did not affect sperm morphology or plasma membrane integrity; however, by removing all free calcium (EDTA 0.5), the sperm motility reduced (64.7% in TGE and 45% in EDTA 0.5; p