Is this Ancestor (2007) by Scott Sigler...?
A plot summary provided within this review mentions the genetic engineering of mammalian creatures by scientists working for a biotech firm named Genada. These creatures were intended to be used as organ donors, and were initially implanted within cows:
A group of scientists at Genada, a biotech company, manage to recreate the genome of the ancestor of all mammals. They use this genome to impregnate cows to give birth to these ancestors. Their purpose? Xenotransplantation, the science of transplanting animal organs into humans. By using the ancestor, they hope to overcome the usual organ rejection as well as the possible jumping of a virus from one species to another (à la the Bird Flu or H1N1). Fortunately, they successfully implant the ancestor blastocysts into the cows. Unfortunately, the ancestor isn’t quite what they hope it will be.
According to another review, the most talented member of the research team working on the project is a female Chinese scientist named Jian:
The science involved in such a process, however, is not without controversy. In creating a mammal with human internal organs, they must envision and produce a creature that none of them has ever seen and that existed long before recorded history. The most talented and creative member of Rhumkorff’s research team is the Chinese female scientist known simply as Jian. While the team continues to experiment and fail with creating an ancestor embryo, Jian thinks outside of the box. She determines that by developing a template of human DNA they will not succeed. What is needed in this situation is the use of a human host, specifically herself, that will allow for successful implantation of the embryo they seek to create.
That review notes that the creatures subsequently "rip their way out of their bovine hosts and prey upon everything in sight:"
A plane with members of the research team and the ‘impregnated’ cows is sent out. However, due to the CIA leaking of the research and other security risks, Genada makes the difficult decision to scrap the entire plan and blow the plane up mid-flight. Of course, the plan is sniffed out. Instead of being destroyed, the plane flies back through a blizzard to crash-land on the same island in Lake Superior from which it left. The experimental cows are set free and found by a local farmer who puts them in a stable with his own livestock. When the new cows appear to be sick, the farmer grows concerned – not realizing that these were the same experimental animals that were to have been destroyed in the booby-trapped plane off the island. Alas, he is too late to do anything about it as the lethal fetuses rip their way out of their bovine hosts and prey upon everything in sight. It turns out these ancestors are not the harmless mammals that were intended but instead a pack of savage, prehistoric creatures with an insatiable appetite and the ability to grow larger with every meal.
The Siglerpedia website provides a lot more information on the plot and characters.
