This little piggie went to the science lab
Watch out, little white lab mouse. Barnyard animals are gunning for your job.
A bullish group of agricultural scientists says that farm animals have been vastly underrated as a resource for improving human health -- and they’re vying for some of the billions of dollars the government invests in biomedical research.
The human-sized hearts and blood vessels of pigs are well-suited for the study of cardiovascular disease, they say. Cow embryos have the unusual ability to start forming body structures in lab dishes, where they are easy to observe. Chickens are the only animals besides humans known to suffer from ovarian cancer.
“Farm animals are more closely related to humans genetically and physiologically,” said Jim Ireland, a professor of animal science and physiology at Michigan State University in East Lansing, who notes with pride that at least 17 Nobel Prize winners used barnyard species in their experiments.
However, he lamented, “most of the research dollars have been invested in using the mouse.”
Mice, of course, have many advantages as research tools. Hundreds can be housed, fed and scrutinized for the same cost of studying a single pig or cow. Research labs all over the world are organized around mice, and an entire industry has sprung up to supply the critters in endless genetic variety and all the paraphernalia needed to study them.
At UCLA, mice are central in about 1,000 of the 1,200 research projects involving live animals, and most of the rest use rats, said radiation biologist William McBride, chair of the university’s animal research committee. The rodents are simply more practical.
“We don’t have green fields,” McBride said.
But livestock are convenient in other ways, agricultural researchers say.
They can be studied for months or even years, with their normal barnyard lives interrupted periodically for blood tests and other medical exams. Some farm animals reside in state-of-the-art facilities that meet guidelines set by the National Institutes of Health. When the research is over, most simply return to their herds.
Nearly all the livestock are ultimately destined for the slaughterhouse -- a source of cash that helps defray research costs, said animal physiologist Larry Reynolds of North Dakota State University in Fargo who uses sheep to study fetal nutrition during pregnancy.
Animals given experimental drugs are kept out of the food chain for safety reasons, and others must be sacrificed to collect data such as gene activity. In those cases, the animals are slaughtered according to federal standards, and their carcasses are incinerated, Reynolds said.
Dozens of land grant universities already raise farm animals for agricultural research, and some of the studies have become so sophisticated that it’s almost impossible to ignore their implications for human health. To cite one notable example: The artificial insemination and in vitro fertilization techniques used routinely in people were first developed by agricultural scientists to help cattle breeders improve the quality of their herds.
Biologist Russ Hovey’s interest in dairy production led him to study mammary gland development in cows and sheep. As he was pursuing his PhD, he realized the genes and hormones he was focusing on could help explain breast cancer development in humans.
After a stint at the National Cancer Institute to beef up his biomedical credentials, Hovey is back on the farm. As part of the animal science department at UC Davis, he is using pigs to find the hormones and genes that trigger changes in breast development -- and hoping to learn what goes wrong in human breast cancer.
“We know the human is different from the mouse,” he said. “We really should be asking what other species might look more like a human.”
For Animesh Barua, who investigates reproductive immunology at Rush University Medical Center in Chicago, the answer is white leghorn hens.
About half of the hens develop ovarian cancer by the time they are 2 or 3 years old. That makes it possible for Barua and his collaborators at two University of Illinois campuses to track the birds from the moment they are hatched until they become ill.
Barua has zeroed in on a protein that circulates in the blood when the hens are in the earliest stages of ovarian cancer. The team is studying more hens to see if the protein can be used in an early detection test analogous to the prostate-specific antigen test that can flag prostate cancer in men.
Barua is also using hens to develop an ultrasound exam to pinpoint the blood vessel growth that precedes the deadly tumors. Finding early signs of ovarian cancer is crucial, he said, since “this is one of the very difficult malignancies that you cannot detect” until it is too late.
Of course, there is an added benefit to piggybacking biomedical studies onto existing livestock research -- a chance to tap into the NIH’s multibillion-dollar research budget.
That money is no small matter to agricultural scientists, who have absorbed a 44% cut in federal and state research funding over the past two decades, according to a recent report. Animal science faculties at larger land grant universities are half the size they were 30 years ago, and entire breeds of livestock are disappearing from campuses as well, the report found.
“The reality is we need the money,” said Reynolds of North Dakota State University.
The U.S. Department of Agriculture allocated $32 million to university scientists studying livestock in fiscal year 2007. That’s dwarfed by the roughly $24 billion that the NIH makes available to outside scientists for biomedical research.
Proposals to fund studies involving larger animals, however, are often met with skepticism. “The people that are on NIH grant review committees are obviously people that mostly work with rodents,” Reynolds said. “I think there’s perhaps a bias toward rodents.”
And with good reason, said Kent Lloyd, associate dean for research in the UC Davis School of Veterinary Medicine. Mice reproduce in as little as three weeks -- compared to 21 weeks for sheep and 38 for cows -- making it easy for scientists to breed thousands of unique strains that are susceptible to specific diseases. Their DNA has been sequenced, and their genes can be rearranged quickly and precisely using embryonic stem cells and other biotechnology tools.
With time and money, maybe some of those assets could be replicated in another species, he said, “but why do it?”
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