Researchers discover cattle pregnancies can succeed without a protein long considered essential
For many years, scientists believed that a protein known as interferon tau (IFNT) was essential for successful pregnancy in cattle. This protein is produced by the developing embryo and was thought to send a crucial signal to the mother, helping maintain the pregnancy. However, new research from Ludwig Maximilian University (LMU) Munich has challenged this long-standing scientific belief.
The study, recently published in Nature Communications, found that cattle embryos can establish and maintain pregnancies even without producing interferon tau. The discovery could change how scientists understand reproduction in cattle and may lead to new strategies to improve fertility in livestock.
The research team, led by Dr. Asghar Ali, postdoctoral researcher at LMU’s Gene Center Munich, and Professor Eckhard Wolf, Chair of Molecular Animal Breeding and Biotechnology and Vice Dean at LMU’s Faculty of Veterinary Medicine, used CRISPR-Cas9 gene editing to eliminate all functional copies of the IFNT genes in bovine cells, used advanced gene-editing technology called CRISPR-Cas9 to remove all functional copies of the IFNT genes from bovine cells. These modified cells were then used to create cloned embryos, which were transferred into recipient cows.
Researchers expected the embryos to struggle because of the absence of IFNT. Instead, they observed something surprising. The embryos developed normally during the earliest stages of pregnancy and successfully established pregnancies in the recipient animals.
The most remarkable outcome came when two healthy female calves were born in February 2026. Genetic testing confirmed that the calves lacked functional IFNT genes, proving that successful pregnancies and births could occur without the protein that had long been considered indispensable.
According to the researchers, the findings challenge one of the most accepted theories in reproductive biology. For decades, IFNT was viewed as the key signal that allowed an embryo to communicate with its mother and prevent hormonal changes that could end a pregnancy. The new evidence shows that cattle can achieve successful pregnancies through additional biological mechanisms.
“Our findings challenge a fundamental assumption in reproductive biology. We have demonstrated that cattle embryos can establish pregnancies and develop to term without producing interferon tau, a signal previously considered indispensable,” said Ali.
To better understand what was happening, the scientists studied how the mother's uterus responded to embryos that did not produce IFNT. They found that the usual interferon-related responses were missing. Despite this, the pregnancies continued and developed normally.
This result suggests that cattle possess alternative communication pathways between the embryo and the mother. These pathways may help maintain the hormonal environment necessary for pregnancy, even when IFNT is absent.
One possible explanation involves a signaling molecule known as prostaglandin E2. Researchers believe this molecule may help support the corpus luteum, a temporary structure in the ovary that produces progesterone. Progesterone is a critical hormone that helps sustain pregnancy.
Although prostaglandin E2 appears to be a promising candidate, scientists say more research is needed before its role can be confirmed. Understanding these alternative mechanisms will be an important focus of future studies.
The discovery has major implications for livestock production and animal breeding. Early pregnancy loss continues to be a significant challenge for cattle producers around the world. Failed pregnancies can reduce productivity and increase production costs.
By identifying the biological signals that support pregnancy outside of IFNT, researchers may eventually develop new tools and management strategies to improve reproductive success in cattle herds. Better fertility rates could benefit both dairy and beef producers by increasing efficiency and reducing losses.
The findings also demonstrate how modern genetic technologies can help answer important scientific questions. Gene-editing tools such as CRISPR-Cas9 enable researchers to study the function of specific genes in ways that were not possible just a few years ago.
Beyond agriculture, the study contributes to a broader understanding of mammalian reproduction. The results highlight the complexity of pregnancy and reveal that biological systems often have backup mechanisms to ensure successful development.
“These results fundamentally change our understanding of how the embryo communicates with the mother. The next challenge is to identify the alternative signals that allow pregnancy to be established and maintained,” said Wolf.
Researchers believe that uncovering these hidden pathways could lead to new discoveries in reproductive science and animal health. As scientists continue their investigations, the study serves as a reminder that even long-accepted scientific theories can be challenged by new evidence.
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