Benefits of reproductive technologies like estrus synchronization (ES) for natural or artificial breeding are old news.

“Improving traits of major economic importance in beef cattle can be accomplished most rapidly through the selection of genetically superior sires and widespread use of artificial insemination (AI),” says David Patterson, University of Missouri (MU) animal science professor. “Procedures that facilitate ES in estrous cycling females and induction of an ovulatory estrus in peripubertal heifers and anestrous postpartum cows will increase reproductive rate and expedite genetic progress.”

Moreover, Patterson explains using AI and ES together can increase profits through changes in calving distribution patterns; a higher percentage of cows calving during a more concentrated timeframe; and more calves hitting the ground earlier in the season, making them older and heavier at weaning time.

Yet, these technologies continue to gather dust.

AI use in the industry

According to the most recent Cow-Calf Survey, conducted in 2007 by the National Animal Health Monitoring Service, 5.2% of mature cows were bred via AI exclusively or followed up with by natural service in 2007; 16.3% for heifers.

As for utilizing AI or natural breeding in tandem with ES, Patterson explains, “Although hormonal treatment of heifers and cows to group estrous cycles has been a commercial reality for more than 30 years, beef producers have been slow to adopt it.”

Patterson reckons part of the slow rate of ES adoption stems from producers who tried it but failed because the females used were poor candidates. Specifically, heifers that hadn’t yet reached puberty and cows that didn’t return to normal estrous cycles following calving.

With deliberate selection of proven sires and fixed-time AI (FTAI), which requires ES, Patterson points out producers can quickly make a gargantuan stride in genetic improvement. Using ultrasound to determine pregnancy in order to re-synchronize and re-breed cows and heifers that don’t conceive with the first breeding ratchets the speed up another notch. Using sexed semen can improve it further.

In an MU demonstration project, FTAI was utilized in 73 herds across the Missouri, accounting for 7,028 cows. The average pregnancy rate with a single insemination was 62%. Keep in mind there is no heat detection with FTAI, which eliminates a significant barrier that existed before reliable, economic AI synchronization strategies were developed.

“The progress that has been made in developing these technologies over the past 10 years has been phenomenal,” Patterson says.

Incidentally, that 62% average pregnancy rate is in line with natural breeding and no synchronization; just turning the bulls in.

Mike Smith, MU professor of reproductive physiology, explained at the Applied Reproductive Strategies for Beef Cattle Conference in August: “For natural service, expected pregnancy rates are normally 60-70% during 21 days of breeding, assuming the bulls are fertile and that 100% of the cows and heifers are cycling. However, a pregnancy rate of 60%-70% over 21 days is unusually high for natural service since rarely are all the heifers and cows cycling at the start of breeding season.”

Smith emphasizes a common cause for poor FTAI performance is using cows and females that are poor candidates, such as heifers that haven’t yet reached 65% of their mature weight or cows in poor body condition.

According to Patterson, producers involved in the demonstration project had few questions about the necessary steps and protocols required by FTAI. Instead, most questions revolved around sire selection, determining which profile of traits they should consider in potential sires, relative to their cowherds.