Leaner pork for consumers could be a benefit of research on human obesity, according to ARS scientists. They've been intrigued by two hormones, neuropeptide-Y and leptin. These hormones work like a traffic light for the appetite—both in pigs and people. Neuropeptide-Y, found in the brain, is a "green light" that stimulates appetite. Leptin, the red light, is in fat. It signals the brain that the body is nourished. Researchers found that giving pigs leptin injections increased the amount of growth hormone in their bodies and made them eat less. Since growth hormone produces muscle, the new leptin approach may have potential for producing meatier, leaner pork.
Richard B. Russell Research Center, Athens, GA
C. Richard Barb, (706) 546-3584, rbarb@uga.cc.uga.edu

Adding oil or spice to broiler chicks' feed can help stave off intestinal parasites that cause avian coccidiosis, ARS studies suggest. Coccidiosis is caused by Eimeria parasites. These parasites infect the upper, middle or lower parts of a chicken's intestines. The parasites cause intestinal lesions that hinder the bird's ability to absorb feed nutrients, severely stunting the bird's growth. Producers spend more than $100 million annually to overcome the problem by adding anticoccidial drugs to starter feeds. But growing consumer demand for drug-free poultry and Eimeria's building drug resistance have spurred the search for alternatives. ARS researchers test-fed groups of day-old chicks a 4-week diet of corn or soybean feed that consisted of 2 to 10 percent oil from menhaden fish, flaxseed or linseed. Birds with a 10 percent linseed oil diet had 64 percent fewer lesions from E. tenella, which attacks sac-like portions of the small intestine called the cecum. Scientists suspect the oil triggers a biochemical response called oxidative stress that helps kill E. tenella. They also tested feeds containing curcumin. It is an antioxidant in a popular spice, turmeric. A 1-percent turmeric diet resulted in 58 percent fewer lesions from E. maxima in the middle intestine.
Parasite Biology and Epidemiology Lab, Beltsville, MD
Patricia Allen, (301) 504-8772, pallen@ggpl.arsusda.gov

The first comprehensive video dictionary of livestock behavior is being prepared by ARS scientists. This will help producers of pigs, poultry, cattle and sheep determine if the animals' feeding, mating, grooming or other behavior is normal—or whether the behavior indicates disease or other problems that need attention. The dictionary will be based on published definitions of animal behavior and include video clips of specific behaviors. Researchers can use the dictionary to explain the behaviors and, if appropriate, recommend changes in production environments. This, in turn, could lead to improved living conditions for the animals and more efficient production methods. To prepare the dictionary, the researchers are cataloging known normal and abnormal behaviors as well as stereotypical behaviors with no identifiable purpose or function. Abnormal behaviors may include tail-biting and ear-chewing in pigs, cannabalism in chickens and wool plucking in sheep. The causes may be linked to the animal's environment. For example, baby pigs will nudge one another with their noses when placed in a barren pen with nothing else to "root" or nudge. Rooting is a normal behavior for pigs.
Livestock Behavior Research, West Lafayette, IN
Julie Morrow-Tesch, (765) 494-8022, jmorrow@www.ansc.purdue.edu

New, simple-to-use equations estimate how much manure a specific dairy herd produces. The equations, developed by ARS scientists, will help agricultural engineers design waste storage systems to prevent pollution of streams and rivers with nitrogen and other nutrients in manure. More jurisdictions now monitor water quality and hold dairy farmers accountable for polluting waterways. So, farmers store manure in pits or other holding facilities until it can be safely applied to fields or recycled as compost. The trouble is, a herd may produce more manure than the holding facilities are designed to contain—especially with high milk-producing cows that eat more. Current design methods use an average value for manure output. The new ARS equations make for a more accurate estimate by plugging in the farmer's own herd statistics. These include the animals' body weight, milk production and composition, feed makeup and number of lactating cows. The new equations also estimate the manure's initial nitrogen content—encouraging design of storage systems that save more of the nitrogen and thus help farmers defray fertilizer costs. And they can give policy makers a more accurate reading on nitrogen escaping into the atmosphere from dairy farms. The research is part of a broad effort to improve management of manure nutrients by studying their complete cycle—from the soil into the forage into the cow and back to the soil.
Nutrient Conservation and Metabolism Lab, Beltsville, MD
Victor A. Wilkerson, (301) 504-8620, victor@ggpl.arsusda.gov

Efforts to eradicate cattle tuberculosis in the U.S. should get a boost from a new, quick diagnostic test developed by ARS researchers. The test is based on a standard high-tech method called polymerase chain reaction (PCR). PCR makes many copies of targeted genetic material. In this instance, that gene material is found only in Mycobacterium bovis, the bacterial culprit in cattle tuberculosis. The new test can detect M. bovis in 2 to 3 days. Current methods take 2 to 3 months. M. bovis is very similar to two other bacteria: M. avium and M. paratuberculosis. The inability to distinguish between them has limited progress toward USDA's goal of eradicating the disease by the year 2000. The new technique correctly identified M. bovis in 93 percent of tissue samples from which the organism had been cultured. Speedier diagnosis will help regulatory agencies take immediate action to identify the most common sources of cattle tuberculosis. imported Mexican steers, captive elk and deer, and large dairy herds with low levels of infection.
National Animal Disease Center, Ames, Iowa
Janice M. Miller (515) 239-8316, jmiller@nadc.ars.usda.gov

Nitrogen fertilizer can increase production of range forage, but the estimated increase in cattle gains will not be enough to pay for the fertilizer. Furthermore, not all plant species benefit equally. Those are two findings from a 14-year study on rangeland fertilization—the longest ever conducted on that subject. ARS scientists observed how annual applications of 20 or 30 pounds of nitrogen per acre in spring or fall changed the mix of rangeland plant species. After 14 years, fertilized areas sported more western wheatgrass plants—but at the expense of plants like blue grama and needleleaf sedge, whose populations declined. Some ranchers may welcome the change, depending on their current forage mix. For example, more western wheatgrass helps feed livestock early in the grazing season. Responses to the extra nitrogen varied significantly among 14 other perennial species surveyed. In all, scientists collected information on 90 plant species.
High Plains Grasslands Research, Cheyenne, WY
Richard H. Hart, (307) 772-2433, rhart@lamar.colostate.edu

Fathead minnow baitfish raised in ponds adjacent to channel catfish ponds will eat zooplankton that thrive on catfish waste. Growers simply circulate the water between the two ponds to put this environmentally friendly waste-disposal system into action. ARS scientists found that the two-pond system increases catfish production while reducing minnow production costs. Accumulated fish waste and uneaten feed now frequently limit farm-raised channel catfish production. That's because as the waste and feed decay, the decaying process uses up oxygen in the pond, creating an unhealthy environment for the fish. Circulation helps increase oxygen levels in the water. Also, the wastewater pumped into the minnow pond provides nutrients to enrich the zooplankton on which minnows feed. This saves about $20 per pond acre instead of using fertilizer to accomplish the same thing.
National Aquaculture Research Center, Stuttgart, AR
Gerald M. Ludwig, (870) 673-4483

Good news for catfish farmers: Copper sulfate, known to cut algae growth in ponds and protect fish against external parasites, won't leave unwanted copper in the fish's flesh. In a 4-year laboratory study for the U.S. Food and Drug Administration, ARS scientists found edible fish flesh contained no extra copper after ponds were treated with copper sulfate. The research also showed that copper concentrations in fish liver returned to normal levels within 8 weeks. Fish farmers lose an estimated $25 million a year to external diseases in catfish. Copper sulfate has been approved by the U.S. Environmental Protection Agency as a herbicide to fight algae. But FDA has not yet approved it to control pathogens and parasites. FDA has deferred enforcement of regulations to restrict use of copper sulfate in aquaculture pending further studies on matters such as its potential to help or harm fish.
National Aquaculture Research Center, Stuttgart, AR
Billy R. Griffin, (870) 673-4483