Angus sire field fertility and in vitro sperm characteristics following use of different sperm insemination doses in Brazilian beef cattle.

The primary objective was to determine if Angus bull fertility varied by number of sperm inseminated. A secondary objective was to characterize the potential impact of random variation on fertility using two identical sperm per dose treatments, which differed only in straw color. Computer-assisted sperm analysis (CASA) and flow cytometry (FC) were used to identify post-thaw sperm characteristics associated with field fertility differences between bulls.

Comparison of fertility of liquid or frozen semen when varying the interval from CIDR removal to insemination.

Cryopreservation allows for long-term storage of semen; however, it leads to damage of sperm that may result in complete loss of viability or changes that possibly decrease sperm functionality. Liquid semen is not exposed to these stressors and may result in a longer lifespan in the female reproductive tract, thus increasing the range in timing of insemination without affecting fertility. The objective of this study was to compare fertility of liquid and frozen semen when varying the interval from CIDR removal to AI using the 7-day CO-Synch+CIDR protocol for synchronization of time of estrus.