Extension Ag Update
May/June 2006
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Hormones Are Degraded by Soils

Francis X. M. Casey, Jiri Simunek, Jaehoon Lee, Gerald L. Larsen, and Heldur Hakk http://jeq.scijournals.org/cgi/content/abstract/34/4/1372, Journal of Environmental Quality

Animal manure normally has estrogen hormones. When manure is applied to soil, these hormones could move with soil water and enter surface water or groundwater. The prolonged presence of estrogen hormones in the surface water environments can result in male aquatic organisms, expressing female traits. Researchers examined the binding strength, mobility and degradation of 17 beta-estradiol and estrone in soil. Within 30 minutes, almost 80 percent of the hormone bound with the soil. Within several hours, about half of the hormone degraded.

How Wheat Kernels "Sing" Is a Sign of Their Quality

Erin Peabody , ARS News Service, (301) 504-1624, ekpeabody@ars.usda.gov

How do you find the "bad" seeds in the bunch? According to Thomas Pearson, a scientist with the Agricultural Research Service (ARS), you listen very closely. Pearson--who’s an agricultural engineer at the agency’s Grain Marketing and Production Research Center in Manhattan, Kan.--has developed an acoustics-based sorter that can distinguish between "clean" wheat kernels and those that have been nibbled on and spoiled by insects.

The idea behind the novel technology is simple. A wheat kernel that’s whole and intact will make a slightly different, high-pitched "ping" when striking a steel plate than the sound made by a kernel that’s been tunneled through by an insect. Because individual kernels are so small, lightweight and hard, any acoustic energy they emit is inaudible to human ears. So, Pearson made sure to outfit his sorting system with a special microphone that can pick up ultra-sonic sounds at exceptionally high frequencies.

After assessing the kernels’ acoustic qualities, the sorter will shunt the insect-damaged wheat kernels from a random sample into one bin, and send "acceptable" kernels into another. It can even pinpoint kernels with tiny insect larvae hiding inside them, a feat that, for grain inspectors, is like trying to find a needle in a haystack. Every year, more than $1.5 billion worth of U.S. wheat and other grains must be discarded or downgraded because of post-harvest damage by insect pests. Despite preventive measures, the pests--ranging from moth larvae to small flour beetles--still manage to find their way into grain storage facilities.

Now, most grain inspectors must laboriously sift through samples of grain by hand, relying on the naked eye to spot wheat kernels that have been spoiled by insects. It can take more than 20 minutes to examine a 100-gram sample, or one weighing about one-quarter of a pound. Pearson’s sorter can analyze the same sample in about 75 seconds, or at a rate of 40 kernels per second. And it successfully detects damaged kernels 87 percent of the time. The technology--which would undoubtedly lead to more accurate estimates of insect damage in wheat loads--is now ready for a private-sector partner to help bring it to market.

Genetic Markers Point Toward Low-Linolenic-Acid Soybeans

Laura McGinnis, ARS News Service, (301) 504-1654, lmcginnis@ars.usda.gov

Agricultural Research Service (ARS) scientists in the Plant Genetics Research Unit at Columbia, Mo., are improving soybean oil’s longevity--and marketability--by lowering its linolenic acid content. Most soybeans contain high levels of linolenic acid, which has double chemical bonds that break down in the presence of air, heat and light, according to molecular biologist Kristin Bilyeu at Columbia. This is a troublesome trait for producers and consumers who want durable, shelf-stable food.

Soy oil is often partially hydrogenated to reduce linolenic acid. Hydrogenation increases products’ shelf life and stability, but produces trans fats (also called trans fatty acids), which several studies have linked to high cholesterol and heart disease. With growing public awareness and new laws requiring food labels to list trans fats, the food oil industry would welcome an alternative to hydrogenated oils. Could low-linolenic soybeans provide the solution?

With colleagues from ARS and Iowa State University (ISU), Bilyeu has developed molecular markers that identify specific mutations in three genes which can be used in plant breeding programs to lower soy oil’s linolenic acid content. Oil from the low-linolenic soybeans does not require hydrogenation. Walter Fehr of ISU and James Wilcox, formerly with ARS, identified the low-linolenic soybean lines in mutant plants that Bilyeu used to identify the mutant genes and develop the molecular markers. Usually, soybean breeders depend on random segregation of the three genes for low-linolenic acid. Using these new markers will improve the identification of soybean genotypes for low linolenic acid content. Eventually, Bilyeu hopes the breeding process will result in stable, nutritious beans for the food oil industry.

The QualiSoy Initiative, under the auspices of the United Soybean Board, is helping to bring seed companies, processors, and food manufacturers together to expand the market for low-linolenic soybean oil. This oil would create a competitive advantage for growers and allow food manufacturers and vendors to market long-lasting products without compromising their nutritional value.

Relaxed Management of Cattle Has Benefits

Sharon Durham, ARS News Service, (301) 504-1611, sdurham@ars.usda.gov

Style matters, even when managing livestock, according to Agricultural Research Service (ARS) scientists who have found that proper management of cattle helps to develop a calm herd--and leads to other benefits as well. Recently retired animal scientist John Stuedemann and other researchers before him at ARS' J. Phil Campbell, Sr., Natural Resource Conservation Center in Watkinsville, Ga., have conducted forage research with their resident herd of Angus cattle that was first established in the 1950s.

The cattle are given “disposition scores” from finishing companies, in this case Tri-County Steer Carcass Futurity in Lewis, Iowa. Calves receive scores from 1 to 5 during each trip through the cattle chute. A score of 1 means the calf is especially docile, while a score of 5 indicates it’s extremely rambunctious. Most of the Watkinsville cattle scores range from 1.0 to 1.9, and most are below 1.5.

Stuedemann’s philosophy is that because the researchers handle them so much, it’s important for the animals to be as calm as possible. Any excitable or unstable cattle are removed to lessen the risk of injury to staffers, especially student workers. Management methods have also been modified to keep the herd relaxed. Aids that were sometimes used to restrain or hurry cattle along were removed from the Watkinsville location a long time ago, according to Stuedemann. Cattle are more likely to go through the chutes calmly when pain is removed from the experience. This conditioning allows researchers to move the animals through the chutes for monthly weigh-ins without incident.

While calm cattle make life easier for those handling them, Tri-County also finds the health and average daily weight gain of the cattle to be excellent. In the five years of custom feeding with Tri-County, approximately 800 head of steers and heifers posted average daily weight gains ranging from 3.1 to 4.6 pounds. Only 30 of the animals graded “Select,” while the rest graded “Choice” or better. A total of 381 head earned the “Certified Angus Beef” label.