While developing a new agricultural industry for the dairy state, a University of Wisconsin-Madison researcher is working to address a major nutrition issue in the developing world: the scarcity of milk.

“Most developing countries, especially in the tropics, recognize the need for milk during infant and childhood development. Milk consumption in the early years is an important component of public health,” says Jack Rutledge, professor of animal science in the College of Agricultural and Life Sciences. The solution to this problem is much more complicated than simply sending dairy cattle to nations in need.

Rutledge”s research focuses on developing and refining a low-cost method to generate embryos that, when implanted into native tropical cows, will grow into milk-producing cows capable of surviving the tropical climate. These specialized embryos-and the oocytes, or eggs, used to make them-stand to become a steady Wisconsin export to the world.

“Marketing sperm from Wisconsin cattle is common, but we could do oocytes,” says Rutledge. “And it won”t hurt our milk industry because we don”t export a lot of milk.”

Tropical nations, where native cows produce very small amounts of milk, have tried various ways to establish productive milking herds on their lands. Many have imported award-winning dairy cattle from the United States and Europe, like Holsteins and Brown Swiss. Each attempt has failed definitively because cattle from temperate climates are not accustomed to tropical heat, humidity, bacteria, parasites and low-nutrient forage. “In terms of milk production,” explains Rutledge, “Holsteins are the best cows in the world, but they are not the best cows for the tropics. When shipped to the tropics, they either die or are unable to reproduce. Either way, they don”t make any milk.”

Subsequent efforts to create milk-producing cows for the tropics focused on mating temperate dairy cattle with tropically-adapted cattle, in hopes of producing a new hybrid breed with characteristics of both parent species.

The first generation of offspring from this mating strategy, called the F1 generation, are usually a success, showing both desired traits-production of milk and adaptation to the tropical climate. But unfortunately, the F1 hybrids are unable to establish a sustainable, successful breed, even though scores of attempts have been made.

“This arises because the two parent species have been separated for half a million years and their genes have evolved so they do things a little differently,” explains Rutledge. “These two sets of genetic instructions don”t work well together after the first generation.”

Rutledge”s research renders this impasse immaterial. He has created hybrid embryos in the lab by combining oocytes collected from Wisconsin dairy cows and imported semen from tropically-adapted bulls. In collaboration with the National Institute for Biotechnology in Hanoi, these embryos have been shipped to Vietnam, implanted into local cows and grown into successful milking cows there.

As in the case of hybrid cattle produced by conventional mating, cattle from lab-generated hybrid embryos are also unable to establish their own breed of hybrids. But, according to Rutledge, with access to oocytes from Wisconsin”s nearly two million dairy cows and state-of-the-art technology, the state will soon be in a position to supply the developing world with an almost limitless quantity of inexpensive hybrid embryos, eliminating the need to establish such a herd.

In the next few years, Rutledge plans to increase the efficiency of each step of the process. “Right now, approximately 30 percent of the oocytes we collect make embryos. Only about 40 percent of embryo transfers result in calves. There is room for improvement,” says Rutledge.

When the technology is ramped up, Rutledge calculates that each calf will cost around $60. Other strategies used to maintain hybrid cattle in tropical areas cost upwards of $300 per head, making the embryos significantly more affordable for developing nations.

“I don”t know of anyone else who has aggressively pursued the idea of creating low-cost, hybrid embryos for tropical systems. Most of the work in the field of in-vitro embryo production is geared toward high-value animals, special animals that are worth tens of thousands of dollars,” says UW-Madison dairy science professor and extension agent Kent Weigel, an expert in dairy cattle genetics and fertility. “Rutledge is trying to apply this technology on a broader scale in developing countries.”

Rutledge”s work is funded by the USDA Foreign Agricultural Service.