What happens when you introduce human genes into cows? Why, you get
cow-people who cows that can produce the nutritional equivalent of human breast milk of course. Yum?
Now before you get your hopes up, no, this stuff is not for your Cap'n Crunch. The reason that Chinese researchers have introduced human genes into cows is to enable them to produce an adequate substitute for human breast milk, since baby formula doesn't offer the same benefits. That said, there's no reason you couldn't drink it, and according to the researchers, "the milk tastes stronger than normal milk," whatever that means.
To get the human bits into the cows, Holstein dairy cow embryos had their DNA modified using cloning techniques. The clones were implanted into surrogates, and so far about 300 of these "humanized" cows have been created. Their milk boasts a much higher nutritional content, 20% more fat, and a variety of proteins that boost immune systems in human babies.
While genetically modified plants and animals are certainly controversial, it's important to keep in mind that we've been genetically modifying everything we can get our hands on for thousands of years through selective breeding. Mixing in human genes is certainly a more aggressive step, but as population increases, it may be necessary to rely more on genetic modification to keep food on everybody's table.
As far as the milk goes, it'll take about ten years to make it to your fridge. In the mean time, I'll be sitting here wondering whether those humanized cows produce human steaks in addition to human milk. Mmmmm, human steaks.