Since the 1990s, producers have been using reproductive hormones to time ovulation and insemination and, ultimately, achieve a pregnancy, said Dr. Todd Bilby of Texas AgriLife Research and Extension at the 2011 DCRC Annual Meeting. However, less than 45% of cows are pregnant after the first service, and a significantly smaller percentage are pregnant after the second service, which means improvements can still be made to reproductive programs.
While the aim of reproductive programs is to increase the number of cows bred and ultimately percentage of cows that become pregnant, often the use of timed A.I. protocols results in fewer pregnancies per service compared with insemination at estrus. Furthermore, 100% timed-A.I. might not be the best solution for improving fertility for dairies that achieve acceptable conception rates for cows detected in estrus.
Bilby shared that establishing a robust synchronization protocol is important to ensure that cows are inseminated in a timely manner. However, dairy farms that achieve acceptable estrus detection and conception rates should take caution as to which synchronization protocol is implemented. Also, the timing of initiation of synchronization protocols is important to consider in order to ensure that estrus detection is not reduced, which can increase the number of cows that are synchronized and result in lower fertility. Future research and on-farm consulting should consider the entire reproductive program, which may involve both cows inseminated based on estrus detection and timed A.I.
To access the 2011 DCRC Annual Meeting proceedings and presentations, click here.
Source: Dairy Cattle Reproduction Council January 2012 eNewsletter