Featured Post

Dr. Jamie Courter is your Mizzou Beef Genetics Extension Specialist

Image
By Jared E. Decker Many of you have probably noticed that things have been a lot less active on the A Steak in Genomics™   blog, but you probably haven't known why. In January 2021, I was named the Wurdack Chair in Animal Genomics at Mizzou, and I now focus on research, with a little bit of teaching. I no longer have an extension appointment. But, with exciting news, the blog is about to become a lot more active! Jamie Courter began as the new MU Extension state beef genetics specialist in the Division of Animal Sciences on September 1, 2023. I have known Jamie for several years, meeting her at BIF when she was a Masters student. I have been impressed by Jamie in my interactions with her since that time.  Dr. Courter and I have been working closely together the last 6 weeks, and I am excited to work together to serve the beef industry for years to come! Jamie holds a bachelor’s degree in animal science from North Carolina State University and earned a master's degree in animal
Post a Comment

ARSBC 2018: Control of Estrus and Ovulation in Beef Cows and Heifers

David Patterson
University of Missouri

The goals of developing FTAI protocols:

  • Easy to schedule and administer
  • Reduce animal handling
  • Result in a highly synchronized and fertile estrus and ovulation


Protocols in Heifers
Make sure you are using the protocols for the current year. Don't use protocol sheets that are several years old, as the protocols are changed and improved.

"With an MGA program, intake is key" Patterson said. He does not recommend top dressing the MGA, but mixing it into a 3 to 5 lbs carrier.

MGA has a much broader distribution of the timing of estrus expression compared to a 14-day CIDR protocol.

With a MGA protocol, you AI 72 hours after PGF2 administration. With a CIDR protocol, heifers are AI'ed 66 hours after PGF2 administration.

You should not see any estrus expression during MGA feeding periods. If you do see heifers in heat, then there is a problem with MGA intake.

Prior to the first breeding season, there needs to be heifer management.
A health program is an important part of this. Another important part is the prebreeding exam. The prebreeding exam includes weight, pelvic area and reproductive tract score (RTS). Reproductive tract scores are a 1 to 5 scoring system of the puberty status of a heifer. A score of 1 is infantile, these heifers are typically not successful in a breeding program. Heifers with a score of 4 or 5 have reached puberty.
Reproductive tract scores should be collected 4 to 6 weeks prior to the start of the breeding season.

In the Show-Me-Select Program, we are seeing an advantage in pregrancy rates when using the 14-day CIDR protocol.

Protocol compliance is key to having a successful AI program.

Protocols in 2-year Old Cows
If you use the 14-Day CIDR-PG protocol in 2-year old cows, you will see a dramatic decrease in heat expression compared to the 7-Day Co-Sync CIDR protocol. However, the pregnancy rates between these two protocols are nearly identical.

Fixed Time AI in Cows
Does the timing of insemination really matter?
Patterson's group ran an experiment in which one group of cows was AI at 54 hours and another group was AI'ed at 66 hours. AI at 66 hours gave higher pregnancy rates, highlighting how important it is to follow the protocols.
Cows that were fix time AI'ed at 54 hours, only 26% had exhibited estrus. The cows in the 66 hour group, 50% had exhibited estrus.

There is perhaps a 3% improvement with the 5-Day protocol compared to the 7-Day protocol in beef cows. However, there are higher labor and time requirements with the 5-Day protocol.

Can fertility be improved with a split-time AI approach? Split-time approach means that you delay artificial insemination of those cows that have not expressed estrus at the fixed-time AI time and delaying insemination by 20 to 24 hours.

It is not necessary to administer GnRH to those heifer or cows that have expressed estrus prior to the fixed artificial insemination time. By using split-time approach you need to use much less GnRH.

See ARSBC Newsroom for more information. http://www.appliedreprostrategies.com/2018/newsroom.html

Note: this post was live blogged and may contain errors.

Location: Ruidoso, NM, USA

Comments

Post a Comment

Popular posts from this blog

Show-Me-Select Board Approves Genomic Testing Requirement for Natural Service Sires

Image
All bulls purchased after February 1st, 2019 for use as natural service sires in the Show-Me-Select Replacement Heifer Program ™  must be DNA tested to have genomic-enhanced EPDs. All bulls used as natural service sires after February 1st, 2020 must have genomic-enhanced EPDs, regardless of when they were purchased. Seedstock producers classifying bulls as Show-Me-Select qualified in sale books must have genomic-enhanced EPDs on those lots. Bulls purchased prior to February 1st, 2019 will be grandfathered into the program, as is the common practice with all natural service sires. However, this grandfather grace period will end February 1st, 2020. At that time for a bull to qualify for use in the program, it must have genomic-enhanced EPDs. Why the change? The Show-Me-Select Replacement Heifer Program has the goal of producing premium heifers that perform predictably as 2 year olds. The program has a history of requiring Show-Me-Select producers to go beyond typical cat
Read more

New Show-Me-Select Sire EPD Requirements Announced

Image
At the January 4th Show-Me-Select Board of Directors meeting, new service sire EPD requirements were approved. All sires, artificial insemination and natural service, must meet minimum Calving Ease Direct (CED) EPD requirements. In addition to yearly updates, two changes were made. First, no Birth Weight EPD requirement will be published. All commonly used breeds now have CED EPDs available. Second, all breeds in the International Genetic Solutions (IGS) genetic evaluation are now set to a common requirement. In the summer of 2018, breeds within the International Genetic Solutions switched to a single-step BOLT multi-breed genetic evaluation. The EPDs for animals in the IGS genetic evaluation are directly comparable across breeds. In 2017, the Red Angus requirement for CED was a CED of 8, which represents the 30th percentile. Less than 5% percent of heifers breed to a bull with a CED EPD of 8 or larger had calving difficulty. We feel that this require is meeting the need to re
Read more