This work examines the effect of the interaction between
different concentrations of two cryoprotectants – glycerol
(GLY) and dimethylacetamide (DMA) – and two methods of
cryopreservation – pellets produced by plunging into liquid
nitrogen and gradual in-straw freezing – on frozen/thawed
chicken sperm variables. Sperm was cryopreserved using: (i)
6% DMA, following the in-straw and the pellet methods (ii)
11% GLY, following the in-straw and the pellet methods; and
(iii) 8% GLY in the in-straw method and 3% DMA in the
pellet method (i.e. reduced cryoprotectant concentrations).
When 6% DMA was used as the cryoprotectant, no differences
were seen between the in-straw and pellet methods in terms of
frozen/thawed sperm variables or fertility (10.8% and 12.8%,
respectively). The viability and motility variables of the frozen/
thawed sperm produced using the in-straw method with 11%
GLY were higher (p < 0.05) than those recorded for the sperm
preserved using the same cryoprotectant and concentration in
the pellet method. However, fertility was extremely low in both
groups (2.1% and 4.2% for the in-straw and pellet methods,
respectively). Finally, the use of 8% GLY in the in-straw
method returned higher sperm viability, intact acrosome and
motility values than the use of 3% DMA in the pellet method
(p < 0.01). No differences were seen, however, in the fertility
results obtained (28.8% and 25.0%, respectively). These
results suggest that cryoprotectant concentrations can be
reduced and still provide acceptable fertility rates.