Extension Ag Update
March/April 2003
Articles Research Resources Internet Links Ag Facts Education

Research Results

Bags May Beat Towers for Forage Storage

Farmers can save on initial costs plus up to $10,000 a year, while greatly reducing the risks from falls and silage gas. As anyone who has driven across rural Wisconsin can tell you, tower silos are one of the most prominent features on the landscape. Up to 100 feet high, these domed towers are the traditional method of storing forage to feed livestock during the winter. In recent years, however, huge plastic "sausages" have sprouted throughout farm country. The sausages are bag silos or silage bags, a new way to store feed for livestock. In terms of cost, safety and feed quality, silage bags—long, plastic tubes tightly packed with chopped forage—may be a better choice for farmers, according to one University of Wisconsin-Madison expert.

"For both initial investment and annual costs, silage bags save farmers money—up to $150,000 initially and $10,000 per year for a 220-cow herd—over using tower silos or bunkers," says Gunnar Josefsson, a farmer health and safety expert with the College of Agricultural and Life Sciences. "Farmers can talk to their county extension agent to find out what the savings would be for their farm. And, in addition to saving money, silage bags greatly reduce the danger of falls and exposure to silage gas."

Safety is an important issue when it comes to storing silage. In Wisconsin, an average of three people die each year in accidents from silage handling—about 10 percent of total farm fatalities—and more are injured. The chief causes of injury or death are related to tower silos: falling from high elevations and exposure to gas from fermenting forage. Bags, at about six to nine feet tall, pose little risk of falls. And, although silage in bags still produces toxic gas, the farmer does not need to enter a confined space.

Most Wisconsin farms use tower silos, but bags are becoming increasingly popular: Josefsson estimates that almost half of farmers use bags, even if not on a regular basis. "When farmers expand their operations, bags are often the best choice because the silage bag system can be tailored to any size herd. With bunkers and towers, if you don’t have enough cows to consume the feed at a certain rate, there can be spoilage from contact with the air."

However, a temporary solution often becomes a permanent fixture: bottom-line cost analysis makes it clear that bags are advantageous at any scale of operation. "Farmers have to purchase bags each year, and some of the costs of silos, such as the initial investment, are hidden because they are included in a mortgage." Josefsson explains. "However, bags are not included in property taxes as silos are, and you can always sell your equipment for bagging—but you can’t sell a bunker or tower, and it adds very little to a property’s sale value."

Bagging also offers options for farmers other than purchasing the equipment outright. Some farmers share the equipment with one or more neighbors, while others rent the equipment from a dealer or hire an operator to bag their forage. However, Josefsson says that it is hard to generalize what option is most cost-effective, as it depends on the farmer’s specific circumstances. Another benefit of bagging is that, if the silage is managed well, using bags can improve feed quality and reduce spoilage, Josefsson adds. With towers or bunkers, farmers must use the feed in a certain order. However farmers can access feed in bags from either end, and can mark which sections contain high-quality feed so that it can be given to top-producing cows.

According to Josefsson, one of the problems with using bags is disposing of the plastic afterwards. Some landfills may not accept bulk plastic, or accept it only with an extra charge. One common practice is to burn the used plastic, but burning is illegal and bad for the environment. "Farmers are really looking for an improved way to properly and legally dispose of waste plastic," Josefsson says. Already, one manufacturer plans to begin accepting and recycling used bags later this year, and Josefsson predicts that the industry, under pressure from farmers, will begin absorbing the cost. Another potential solution is for farmers to bale their plastic and store it until it can be transported to a landfill or recycling plant.

Genome Sequencing Completed for Major Dairy Cattle Microbe

USDA and University of Minnesota scientists have sequenced the genome of the bacterium that causes Johne's disease, a devastating ailment of dairy cattle and other ruminants. A chronic and potentially fatal intestinal disorder that brings about severe diarrhea and weight loss in infected cattle, Johne's Disease is found in 8 percent of beef herds and 22 percent of dairy herds in the U.S. "This major research breakthrough could speed the development of new ways to detect and ultimately eliminate Johne's disease," said Under Secretary for Research, Education, and Economics JOSEPH JEN, who chairs the U.S. Interagency Working Group on Domestic Animal Genomics. The genome sequencing was achieved at two locations: the Agricultural Research Service (ARS) National Animal Disease Center in Ames, IA.

New Trap Kills House Flies

A new trap invented by Agricultural Research Service scientists attracts kills and retains the bodies of houseflies, offering a promising alternative for fly control in areas where food products are stored or prepared. Indoor flies are a potential health hazard to humans because they can transfer numerous disease organisms by just walking across exposed foods. Using chemical pesticides against them is risky if the chemicals are applied near food. And most flytraps have been designed for use either outdoors, or indoors in agricultural settings.

Now scientists Jerome A. Hogsette and David A. Carlson at the ARS Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Fla., have designed a new trap that overcomes those problems. Dubbed "Flybrella" by Carlson, the trap resembles an upside-down umbrella. It can also be used to capture other flying insects, according to Hogsette, a research entomologist with the center's Mosquito and Fly Research Unit.

Flybrella lures flies by taking advantage of their natural attraction to selected chemical odors and to vertically hanging objects. After entering the trap, flies eat the poisonous bait. Dying flies fall inside a tube and into an inverted plastic cone attached beneath. The trap has a removable cylindrical body, a toxicant panel and an insect collector. It is designed to contain the dead flies and conceal them from sight. Flybrella hangs from a hook or is attached by ties to electrical cables or other vertical surfaces approximately six feet from the floor.

Two Flybrellas captured 98 percent of flies released in laboratory studies. The trap would be ideal for supermarkets, restaurants and any store where food is prepared or kept. Flybrella is safe and inexpensive to produce. It uses the QuickStrike toxicant strip Hogsette helped develop for agricultural use in the early 1990s. QuickStrike has been very successful at controlling flies in poultry facilities. One of its ingredients is Muscalure, a sex attractant discovered by Carlson and widely used in commercial fly baits.

Latest New-Age Health Supplements: Garlic, Kale And Beets?

With so many people using over- the-counter herbal supplements as a means to promote health, one UW-Madison researcher is wondering why we don't hunt for health-promoting properties among the ordinary plants we grow for food. According to Kirk Parkin, a food scientist at the College of Agricultural and Life Sciences, "There's no reason to believe that exotic botanicals are the only plants that have specific, health-promoting benefits.

Domesticated plants do, as well." That's why Parkin has launched a research program aimed at uncovering the healthful properties, such as cancer prevention, of the decidedly unglamorous crop plants cultivated here in Wisconsin, such as garlic, kale, beets, corn and green beans. Not only do common vegetables carry a lower price tag and a safety record spanning thousands of years, but they also contribute to Wisconsin's economy.

The popularity of exotic herbal supplements with names like echinacea, feverfew, valerian and goldenseal has soared. So have concerns about their effectiveness and safety. Last year, the Food and Drug Administration alerted consumers to the possible liver-damaging effects of kava, a popular herb for relieving anxiety and insomnia. The Secretary of Health and Human Services recently urged mandatory warning labels for the stimulant ephedra. And doctors have begun cautioning about the risks of using herbal supplements in combination with prescription drugs and immediately before surgery.

On the other hand, in a study published in the September 2002 issue of the Journal of Food Science, Parkin's research group demonstrated that everyday vegetables might indeed play a role in human health beyond simple nutrition. Using a well-known in vitro technique for screening possible cancer-preventive agents, they showed that crude vegetable extracts triggered increases in protective proteins, called phase II enzymes. Phase II enzymes work in concert with another group of proteins, called phase I enzymes, to detoxify cancer-causing agents in the liver and other organs, and purge them from the body. Due to these activities, high levels of both sets of proteins — but especially phase II enzymes — are thought to help protect against cancer.

Among the vegetable extracts they tested, an extract of sweet corn showed the greatest effect, causing a 13-fold jump in enzyme levels. Kale extract raised the enzymes eight-fold, snap beans increased them five-fold and beets two-fold. "Our results suggest that commonly consumed vegetables contain components that can elevate phase II enzymes in vitro, and have the potential to be used as dietary sources of cancer chemopreventive agents," says Parkin. Many of the extracts also showed pronounced antioxidant activities.

But aren't people already receiving these benefits by eating their veggies? Probably not to the extent they could. In its last dietary assessment of the U.S. food supply, the U.S. Department of Agriculture found that although Americans ate an average of 20 percent more vegetables in 1996 than in 1970, just three types accounted for half of all servings: head lettuce, canned tomatoes, and potatoes, including chips and french fries. Another 15 percent of servings came from dehydrated potatoes, fresh tomatoes, garlic and carrots.

To entice people into eating a wider variety of plant foods, Parkin believes scientists need to continue to pinpoint the health benefits of eating specific vegetables. "The USDA has been advocating all along that eating a diversity of fruits and vegetables in copious quantities will promote health, and I'm convinced it will," he says. "But I think if you simply tell the public that eating vegetables is good for them, you don't get much of a response. To change eating habits, you need to give a specific reason why eating certain vegetables will benefit them."

Research such as Parkin's could also lead to new vegetable-based dietary supplements for the staunchly veggie-phobic. Parkin cautions that his research group still has much work to do toward characterizing the specific compounds in vegetables that carry cancer-protective effects, and demonstrating a true health benefit for people. Still, he's convinced that today's neglected, humdrum plant foods could be an important part of tomorrow's preventive medicine.