Discovery

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Archive for the ‘Genetics’ Category

From Pig Hairs and Genes, A Possible Solution to a Nagging Problem

Even the technological wonders of genetic science can still require some basic, mundane tasks, like cutting pig hairs.

“I spent many, many, many hours snipping the roots of pig hairs,” says Kaitlin Wilson, a Washington State University master’s student in Animal Science. She processed five to seven hairs per pig, in fact, from a total of 272 pigs.

“It was a lot of hair,” says, Wilson, who raised cows and pigs for 4H while growing up on a Connecticut horse farm. “It took me days, hours and hours and hours.”

Pig's tail photo courtesy of http://www.flickr.com/photos/ashleyb/

But inside those roots lay just enough DNA to determine each pig’s genetic makeup. And by comparing their DNA, Wilson and colleagues here and in Norway found what they believe is the first genetic basis for a particularly gruesome and costly problem: tail biting.

Pigs biting each other’s tails are a big problem. It’s painful and leaves the victim prone to infection.

“We’re not just talking a little bit,” says Holly Neibergs, an assistant professor of animal genetics and Wilson’s advisor. “We’re talking about a kind of mutilation here. They make these huge holes, which isn’t good.”

Farmers in the United States get around the problem by docking, or cutting, pigs tails. This in turn has been criticized as a cruel practice, which is why it is restricted by the European Union. Meanwhile, many EU pigs are getting their undocked tails bitten. One study found roughly one in every 12 pigs falling victim. Factored out over the EU’s 152 million pigs, that’s roughly 13 million bit pigs.

The behavior is thought to stem from modern facilities that don’t have earth or hay in which pigs can play, forage and root. Frustrated, they bite and chew tails. The biting is reduced with more space and materials to mess about in, but that doesn’t eliminate the problem.

Thinking the behavior might also have a genetic component, Wilson processed hairs from Norwegian crossbred pigs that were either biters, victims or neither. She found that, yes, biting pigs had several similar stretches of DNA in their genes. Moreover, she found that victims also had stretches of DNA in common. Biting’s heritability—the degree to which the behavior can be passed between generations—is significant enough that selective breeding can help reduce the number of biters and their victims, Wilson says.

“Who knew the things they could do with genetics?” says Wilson. “I can only imagine where this is going to go in the future.”

Wilson presented her findings at the 2010 Dr. William R. Wiley Exposition of Graduate and Professional Studies held last month in the CUB. Her poster can be seen here (pdf).

The Invention of Sliced Bread Has Nothing on This

Let’s just indulge in a brief moment of bluster and say that Washington State University researchers are on the cusp of what could be one of the greatest inventions since not only sliced bread, but the dawn of agriculture.

Writing in the latest issue of the journal Science, nearly 30 scientists led by Jerry Glover (WSU Ph.D., 2001, soil science) and Regents Professor John Reganold say perennial grains could be here in the next two decades. Such crops reestablish themselves without the aid of plowing or planting. As a result, they can be raised with less fertilizer, herbicide, fuel, and erosion than grains planted annually. The Science authors say that makes them particularly promising for farmers who work marginal land at risk of being degraded by annual grain production. Those farmers, by the way, account for half the world’s growing population.

Back in the day, as in way back at the dawn of ag, grains were perennial. But their ability to regenerate from the plant crown waned as farmers selected seeds for other traits, like yield. Perennial grains would be an elegant, ecologically sustainable way of taking farming back to the future.

You can read more here.

Meanwhile, Reganold shares this electronic conversation with Duane Schrag of the Land Institute, the renowned sustainable agriculture research group in Salina, Kansas.

Schrag: The article mentions earlier efforts at developing perennial grains. What has changed now?

Reganold: Recent advances in plant breeding have made the difference. For example, a plant breeder can characterize and exploit plant genetic variation more easily and effectively through the use of molecular marker-assisted selection. Other molecular advances and technologies, coupled with traditional breeding techniques, make the development of perennial grain crops possible in the next 20 years. This has led to the recent initiation of perennial grain programs in China, India, the United States, Australia, Argentina, and Sweden. All this said, for the great potential of perennial grain crops to be realized, more resources are needed to accelerate plant breeding programs with more personnel, land, and technological capacity.

Schrag: The article notes that while annual crop production does not pose a great risk for the best croplands, it does for marginal lands, which comprise nearly three times the area of the best croplands. What are the key reasons annual production puts marginal lands at risk, and how do perennial grains provide a solution?

Reganold: Marginal lands have poorer quality soils; that is, soils with little to no topsoil, shallow depth, poor structure, low fertility, and/or high acidity or salinity. Many marginal lands occur on steep slopes and are not suitable for annual crop cultivation year after year. They are more susceptible to soil erosion, nutrient depletion, compaction, organic matter loss, and other forms of soil degradation. Marginal lands usually require permanent soil cover to protect them from further degradation. Most annual cropping systems, with the exception for example of continuous no-till systems, don’t provide this. Compared to perennials, annuals typically grow for shorter lengths of time each year and have shallower rooting depths and lower root densities, with most of their roots restricted to the surface foot of soil or less. These traits limit their access to nutrients and water, increase their need for nutrients, and leave croplands more vulnerable to degradation.

The increased use of perennials could also slow, reverse, or prevent the increased planting of annuals on marginal lands, which now support more than half the world’s population. Developing perennial versions of our major grain crops would address many of the environmental limitations of annuals while helping to feed an increasingly hungry planet. For example, with their longer growing seasons and deeper roots, perennials can dramatically reduce water and nitrate losses. Greater soil carbon storage and reduced input requirements mean that perennials have the potential to mitigate global warming, whereas annual crops tend to exacerbate the problem. We know that perennials such as alfalfa and switchgrass are much more effective than annuals in maintaining topsoil. With perennial grains, soils are built and conserved, water is filtered, and more area is available for wildlife.

Schrag: “Farmers need more options to produce grains under different, generally less favorable circumstances …” What less favorable circumstances are anticipated?

Reganold: Less favorable circumstances include marginal lands with much less productive soils and more extreme weather conditions, such as drier or cooler climates. Perennial grains have advantages under these conditions because their longer growing seasons and more extensive root systems make them more competitive against weeds and more effective at capturing nutrients and water. Less favorable circumstances also include farmers, especially in developing countries, having less money to put towards fertilizers, pesticides, water, and fuel. In growing perennial grains, farmers won’t have to replant the crop each year, won’t have to add as much fertilizer and pesticide, and won’t have to burn as much diesel in their tractors.