Relationship of the method of addition and temperature of cryoprotective agents to the fertilizing capacity of cooled chicken spermatozoa

ABSTRACT Three experiments were conducted to determine the relationship of the method of adding (fraction or bulk) and / or holding temperature (41°, 25°, 10°) of glycerol, dimethylsulf oxide or ethylene glycol to the fertilizing capacity of chicken spermatozoa during cooling. No significant effect on fertility was observed when sperm were washed, suspended without dilution in phosphate buffer or milk and cooled to 15 ° in 30 min. With phosphate buffer as the medium, fertility was comparable with that of the control only when ethylene glycol was maintained at 41° or 25 ° prior to addition in fractions (3 equal parts at 10 min. intervals). Similar effects were observed when 4 % DMSO at 25 ° was added in bulk after cooling. However, when DMSO was added to sperm suspended in milk, fertility was significantly reduced regardless of treatment. None of the methods were successful in eliminating the contraceptive action of glycerol. The results indicate that a number of in vitro techniques can be used to maintain the fertilizing capacity of chicken spermatozoa in the presence of 4 % ethylene glycol or DMSO