Beef herd owners might be surprised to find out that 25% of cow pregnancies are lost within in two weeks. It happens all the time, and owners never know it.
"Huge losses occur before farmers know their cows are pregnant," said Mike Smith, University of Missouri animal scientist.
Pregnancy checks in MU research herds show that three days after breeding, 95% of all cows bred are with calf. But 14 to 16 days later, pregnancies drop to 70%.
And while early embryonic death loss cuts calf crops, late embryonic death pushes losses higher. By day 30, pregnancy rates have dropped to 65%. Another 5 to 10% can be lost later in gestation.
Smith, who is conducting research on embryonic losses, says preventing pregnancy losses offers profit potential to the beef industry – but finding the causes of such losses isn't always easy.
"Genetic defects cause one-third of early losses," he said. "Those losses are clearly birth defects and genetic abnormalities," Smith continued.
But that still leaves two-thirds of losses to stress and other factors in cows, Smith notesd.
Though Smith said researchers don't know what causes all of these early embryonic losses, there are a few ways he recommends to save more calves through management.
A few of those management factors include minimizing stress in transportation and from heat.
For example, avoid loading cows on a truck and moving them after breeding, because that can create stress and therefore losses. Heat stress can come from the sun and from toxic endophyte-infected fescue grass.
Until recently, early pregnancy detection was difficult. New tools were developed by MU's animal scientists in the Food for the 21st Century program. They use hormonal assays to detect protein signals from the cow's placenta.
Also, new high-resolution ultrasound monitors show early embryos.
"Earlier, we didn't have tools to do this basic work," Smith said.
Now, with fixed-time artificial insemination, developed at MU Thompson Farm, herd owners regularly achieve 65% of cows pregnant at day 90 after breeding. With timed AI, all cows in a herd are bred on the first day of breeding season.
"When you get over 70% pregnant, that is phenomenal considering embryonic losses," Smith pointed out.
Smith, professor of beef reproduction, will present more of his findings later this month. His research is sponsored by the F21C program and aided by MU student researchers.