Front-Loading Fertility with Timed A.I.

 

By Wes Ishmael

Posted Monday, November 23, 2015

 
 
By Wes Ishmael, BEEF Magazine, August 2015

More weaning weight, cow longevity and postpartum recovery time are some of the benefits of timed artificial insemination.



When it comes to measuring the success of fixed time artificial insemination (FTAI), Cliff Lamb, assistant director of the North Florida Research and Education Center (NFREC) says, “I’m not so sure that pregnancy rate to artificial insemination is all that important…My goal is the percentage of cows that become pregnant in the first 30 days of the breeding season. That is probably the most important economic indicator we have in our operation.”

The NFREC is a research and education campus for the University of Florida. They run their cowherd as a commercial operation, but they shifted from breeding cows via natural service to FTAI giving every female the opportunity to become pregnant through AI. 

Overall season-ending pregnancy rates were 81%-86% before they started synchronizing and using fixed-time AI seven years ago. Those rates are 92% to 94% the past three years. Each year, the calving season gets shorter.

“In five years, we’ve essentially gone down from a 120-day breeding season to a 70-day season, and all cows are eligible to be artificially inseminated on the first day of breeding season,” Lamb explains.

More than the technology, the NFREC underscores the importance of establishing and adhering to realistic management and selection criteria, relative to the goals, environment and resources of each operation. These are the rules Lamb established and has stuck to for the past seven breeding seasons:

  • Every cow will calve by the time she is 24 months of age
  • Must have a calf every 365 days
  • Must calve without assistance
  • Cows must provide sufficient resources for the calf to express  its genetic potential
  • Calves must be genetically capable to perform
  • Cows must maintain their body condition score in their ranch conditions
  • Cows must not be crazy (disposition)

Plus, heifers must be bred within 25 days to remain in the herd. They preg-check 28 days after the 25th day of breeding. Lamb allows that there has been more than one conversation over the years about culling a keeping-quality heifer that bred on day 26. They don’t waver, though.

“They might become a very good animal in someone else’s operation, but in our operation, we want them pregnant earlier,” Lamb says. “I don’t think we’re selecting for fertility. I don’t think we’re selecting for pregnancy. All we’re expecting is those cows to become pregnant in our environment and in our management system. Those cows that we cull from our herd might be very good cows in someone else’s management system somewhere else, but they just don’t seem to work in our operation.”

Post-partum Interval

Lamb utilizes results from a larger study he was involved with in South Dakota to demonstrate another primary gain from timed AI—increased days between calving and the next breeding season. The FDA study included eight operations and 1,700 cows, synchronized utilizing the 7-day CO-synch plus controlled internal drug release (CIDR) protocol (GnRH and CIDR on day one; CIDR removal and prostaglandin on day 7; GnRH and timed AI on day 10).

Three herds achieved what many would consider to be acceptable first-service pregnancy rates of 56.9% to 65.8%. The other five had rates (44.4% to 50.4%) that many would consider to be disappointing.

For anyone with little fixed-time AI experience, Lamb emphasizes the need for realistic expectations.

“The expectations need to be different for every cattle operation depending on how the cattle are treated from year to year,” Lamb says. “Very often, I think we have very unrealistic expectations of what we can get from our synchronization system. If you’ve synchronized year after year, you can say, ‘Yeah, I can expect a 60% pregnancy rate or 65% and do it.’ If it’s you’re first time, expecting a 60% pregnancy rate might be unrealistic.”

Researchers found only one consistent difference between the herds with higher rates and the others.  

“These three herds had all utilized AI for eight years or more consistently, regardless of the pregnancy rates they got the year before,” Lamb explains. “They continued to stay committed to synchronization year after year.” The others may have utilized AI from time to time, but not year after year.

Lamb compared the calving distribution between herds that had never used AI before with those that used it consistently. 

In the bull-bred herds, 44% of the calves were born from the day the first calf arrived to 30 days later. Lamb points out these were well-managed operations with calving seasons of less than 75 days.

The average postpartum interval (PPI) in these herds by the start of the next breeding season was 64 days. There were 43% of cows with less than 50 days PPI at the start of the next breeding season.

In the timed AI herds, 88% of the cows calved in the first 30 days of the calving season. The average PPI to the start of the next breeding season was 79 days. Only 7% of the cows were less than 50 days PPI at the start of the next season.

“We’re increasing the days of postpartum—that period of time where they can recover and start their estrus cycle before the next breeding season—by 15 days,” Lamb stresses. “A higher percentage of those cows have the chance to start cycling and become pregnant in the next breeding season. So, anything we can do to frontload the calving season is going to increasing our fertility to the next breeding season.”

Not to mention the numbers on the scale ticket and the bank draft at sale time. 

All told, Lamb explains shifting the NFREC herd to fixed-timed AI continues to generate substantial economic return, compared with the natural breeding they were doing before. That’s before considering genetic improvement.

“We’re generating $50,000 more to that operation (about 300 calves annually, valued the same year-to-year) just by putting pressure on that herd for pregnancy, just by creating rules that we expect every cow in that herd to become pregnant when we want them to become pregnant.”

For the free AI Cowculator app developed by Lamb and his peers, go to the android or apple app store.

You can listen to Lamb’s presentation by clicking here.