As a young man working on his family ranch, Colorado State University reproductive scientist Thomas “Tod” Hansen checked cattle for pregnancy using conventional rectal palpation – a routine and inexpensive method that can be stressful for cows and physically demanding for technicians.
There’s got to be a better way, he thought.
Hansen, now director of the highly regarded CSU Animal Reproduction and Biotechnology Laboratory, has become a leading scientist working to understand the dynamics of livestock pregnancies at the molecular level. He also is leading new discoveries in the economically devastating bovine viral diarrhea virus (BVDV), in part because of links between cattle pregnancy and viral infection.
For these and other achievements, the American Society of Animal Science recently conferred to Hansen its Animal Physiology and Endocrinology Award for important research contributions to the livestock industry.
“Dr. Hansen has emerged as the leader in maternal recognition of pregnancy in ruminants,” CSU Distinguished Professor Emeritus George Seidel, an eminent reproductive scientist, wrote in an award-nomination letter. “His seminal discoveries have advanced our basic understanding of the mechanisms involved in embryo recognition by the mother, and also have provided new diagnostic tools to identify problems that limit reproductive efficiency.”
Hansen’s discoveries have led to several patents, critical steps in innovation and the introduction of new technologies to the marketplace. In this case, the patents were issued for blood markers that Hansen is using to develop pregnancy and viral screenings that would represent significant progress in managing livestock health.
“Our goal is to find the non-virally infected and non-pregnant animals in order to better manage reproduction and animal health,” Hansen explained.
He is developing a blood test to detect pregnancy in cattle as early as 16 days after breeding, compared to at least 25 days with ultrasound and some 35 days with rectal palpation. Such a test would detect pregnancy – or, more importantly, non-pregnancy – earlier than others on the market.
The time savings means a cow that is not pregnant could be quickly rebred so she remains productive and on pace with the rest of the herd, particularly important for purebred cattle operations and advanced dairies with thousands of milking cows. Considering there are more than 9 million dairy cows in the United States, the savings to producers would mount quickly.
Hansen also is investigating use of markers in new serum screenings that would identify cows and cattle fetuses infected with BVDV. The research is important in the context of reproduction because BVDV is transmitted from cow to unborn calf, resulting in aborted and stillborn calves, calves that die young, and calves that live but spread the virus to entire herds; the latter group, known as persistently infected, is the main source of BVDV infection in cattle.
Such knowledge is important because BVDV is difficult to control: Vaccination programs are not universally implemented or 100 percent effective, and the virus spreads easily through the mouth or respiratory tract.
Much of Hansen’s work centers on interferon, protein that signals pregnancy to a cow’s body and helps retain an embryo. He found that interferon triggers the creation of another protein, known as ISG15, a marker that could be central to identifying both pregnancy and viral infection.
“Subsequent research has demonstrated that ISG15 has important roles during pregnancy in all mammals studied to date, ranging from mice to humans,” Seidel wrote in his nomination letter, suggesting the far-reaching implications of Hansen’s discoveries.
A professor in the CSU Department of Biomedical Sciences, Hansen came to science through hands-on work on his family cattle ranch near Fort Collins. During calving season, he often referred to a CSU book titled, “Artificial Insemination and Reproductive Management of Cattle,” co-authored by Seidel, a member of the prestigious National Academy of Sciences and a pioneer in cattle reproduction.
“This book was like a bible to me,” Hansen recalled, reaching to an office shelf to retrieve his original, tattered copy.
He also was intrigued by embryo transfer and cryopreservation of gametes – advances brought to the family ranch by Hansen’s father, an obstetrician-gynecologist naturally interested in advances in reproductive science.
Seidel, who helped determine how to sort cattle sperm by gender, reflected on his colleague’s scientific honor.
“Tod has remarkable scientific expertise and success, as well as integrity and willingness to help others,” said Seidel, who is retired but still active at the CSU Animal Reproduction and Biotechnology Laboratory. “The award is for the science. The other is icing on the cake.”