CONTACT: Jack Rutledge (608) 263-6993, rutledge@calshp.cals.wisc.edu
MADISON – A University of Wisconsin-Madison researcher is building on one of
Wisconsin’s great strengths 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 eggs used to make them – stand to become a steady Wisconsin export
to the world.
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.
While the first generation of offspring is usually a success, they have been 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 eggs 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 eggs 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 (eggs) we collect make embryos.
Only about 40 percent of embryo transfers result in calves. There is room for
improvement,” he says.
When the technology is ramped up, Rutledge calculates that each calf will cost
around $60, roughly five times cheaper than other strategies used to maintain hybrid
cattle in tropical areas.
“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.
###
– Nicole Miller, nemiller2@wisc.edu
