The effect of different freezing rates on fertilizing ability of frozen-thawed chicken spermatozoa.
The effect of two different freezing velocities (1 °C/min and 6 °C/min) on fertilizing ability of spermatozoa from the roosters selected for high fertility with frozen-thawed spermatozoa and the randomly selected control males was determined. Significantly (P<0.05) higher fertility was obtained when semen of the selected male was frozen at a rate of 1°C/min to -70°C. In contrast, semen frozen at 6°C/min until -70°C showed no significant difference in fertility between two male lines. The results of the present study indicate the possibility of male selection for higher freezability of spermatozoa. Better viability and fertilizing capacity of frozen-thawed fowl spermatozoa were suggested to be obtained with a freezing rate of 1°C/min.