The first live offspring from super-cooled pig embryos have been produced by ARS researchers. The scientists used a process called vitrification, which preserves the pig embryos in a cooled state without allowing ice crystals to form, crucial for their storage and later development. Slow-cooling below normal room temperatures–about 15° C or 59° F–is required during conventional embryo freezing methods. But embryos suffer physiological and structural changes when going from normal body temperatures to these cooler temperatures. This is why pig embryo survival, after slow cooling or conventional freezing, has been so poor. The new vitrification technology offers the $11 billion-a-year swine industry greater opportunities for global expansion. It will allow producers to import and export valuable breeding stocks and unique germplasm without worrying about shipping live animals. Producers and consumers benefit in the long run through availability of improved livestock, providing safe, wholesome and healthy pork products at reduced costs. Germplasm and Gamete Physiology Laboratory, Beltsville, MD John R. Dobrinsky,(301) 504-8134, bigjohn@lpsi.barc.usda.gov

After trying a new approach on herd worming suggested by an ARS researcher, Pennsylvania dairy farmer Larry Lohr saw his cows give an average 4 pounds more milk per day in 1997. Plus, the cows' body weights stayed up and they excreted less nitrogen, a potential pollutant. Lohr collaborated on a 3-year ARS study of his farm, aimed at keeping brown stomach worms from nibbling into dairy producers' profits. Under the ARS-developed regimen, Lohr will de-worm his cows twice–once in spring and once in fall–instead of five to six times as in previous years. Lohr is one of a growing group of dairy producers trying to increase their bottom line by letting cows graze when possible, rather than cutting, drying and storing the feed and serving it up later. The practice lowers feed costs. But milk production often "roller coasters" throughout the season. The study was funded by a grant from USDA's Sustainable Agriculture Research and Education Program. The ARS researcher observed that Lohr's 19-day grazing rotation perfectly fit the brown stomach worm's life cycle. Lohr followed the researcher's advice to let the cows "vacuum up" infectious larvae while they graze each paddock at the start of the season. The spring worm treatment killed these ingested larvae before they could mature and deposit eggs in the feces–which would re-infest the pasture. Immunology and Disease Resistance Laboratory, Beltsville, MD Louis C. Gasbarre, (301) 504-8509, lgasbarr@ggpl.arsusda.gov

A set of new genetic probes could someday help save horses worldwide from wormlike nematode parasites.ARS scientists helped other researchers in Scotland and Australia develop the new probes based on the worms' DNA sequence. Each year, any of about 65 species of nematodes that infect horses cost owners and insurance companies millions of dollars. The parasites lower the animals' performance and productivity and sometimes kill them. Currently, accurate diagnosis is impossible because eggs in feces or larvae cultured from the eggs cannot be identified to species. Thus, treatment isn't as selective as owners and veterinarians might desire. An ARS worm expert worked with an international team to produce a checklist of nematodes that inhabit a horse's large intestine during the parasite's adult stage. Recently, ARS scientists organized an international workshop to adopt updated, uniform nomenclature for the pests. Eventually, the new probes might allow horse owners to be more selective with antiparasitic drugs. This would reduce treatment costs and extend a drug's useful life by avoiding its overuse. In the meantime, the probes will help researchers in several ways. They will help determine whether a nematode is drug-resistant or is a serious pathogen. The probes will also be used to identify the predominant species in larval cyathostomiasis--an emerging horse disease. Researchers can also use the probes to evaluate, select and enhance natural control agents for nematodes. Biosystematics and National Parasite Collection Unit, Beltsville, MD Ralph Lichtenfels, (301) 344-5364, rlichten@ggpl.arsusda.gov

Several proteins that probably help a biting gnat transmit bluetongue, a virus of cattle and sheep, have now been pinpointed by ARS scientists.The gnat, Culicoides variipennis, is also called a biting fly, midge, or, because of its small size, a "no-see-um." The proteins increase blood flow to the bite area, prevent aggregation of platelets needed to close off the wound and inhibit immune system cells that would help a victim fight off the virus. Researchers already knew about similar proteins in other biting insects and ticks. But the ARS team is the first to show that C. variipennis secretes these specialized molecules from its salivary glands. The proteins may prove to be a better tool than the virus itself for developing a future bluetongue vaccine. That's because the many strains or serotypes of the virus can quickly develop resistance to a virus-oriented vaccine. This problem wouldn't occur with a vaccine targeted to the gnat's salivary- gland proteins. Bluetongue annually costs the U.S. livestock industry an estimated $120 million in lost trade. Countries without the disease won't accept some American livestock exports. Arthropod-borne Animal Diseases Research Laboratory, Laramie, WY Walter J. Tabachnick, (307) 766-3600, tabachni@uwyo.edu

Calves castrated at birth suffer less stress than calves castrated at six months of age. But the method of castration–banding or surgical–can make a difference in the amount of colostrum the calves consume. Colostrum is high-protein milk that's produced by the mother for a few days after giving birth. Colostrum contains many antibodies and increases the calves' resistance to disease. Calves castrated at birth using the banding method spend more time lying down and appear to spend less time nursing–and getting colostrum–than calves castrated at birth by surgical means. Weaning is a stressful time for calves. That stress can be heightened by production practices such as castration. Animals are castrated primarily to reduce the danger of handling males, who are often aggressive, if they're allowed to reach sexual maturity uncastrated. Castration also improves the taste and tenderness of beef. Meat from uncastrated cattle can be tougher and may carry an unpleasant odor. Livestock Behavior Research Unit, West Lafayette, IN Julie Morrow-Tesch, (765)494-8022, jmorrow@www.ansc.purdue.edu/

A natural compound can help cows ward off costly mastitis infections around calving time, ARS researchers have shown. The cows make this compound–cytokine G-CSF–in skin and other body cells. G-CSF stimulates bone marrow to produce white blood cells that fight infections. In tests, cows were injected with the compound daily from days three through seven after calving. On the sixth day, the cows were challenged with a bacteria and their reactions were monitored for several more days. Half of the cows receiving G-CSF did not become infected. The other G- CSF-injected cows had shorter and less severe infections than the cows in the control group. All the G-CSF recipient cows ate well and gave more milk than cows receiving only saline. Each year, dairy producers lose as much as $180 per cow because of mastitis, an infection of the mammary gland. These infections occur most often around calving time on more than 95 percent of all dairy farms. The benefit of using G-CSF as a preventative: less use of antibiotics in cows to treat mastitis.

National Animal Disease Center, Ames, IA Marcus E. Kehrli, Jr., (515) 239-8462, mkehrli@nadc.ars.usda.gov/

Animal urine could become a new source of valuable hormones and other human drugs. ARS and New York University researchers have developed transgenic mice that produce, in the lining of their bladders, human growth hormones that accumulate in the urine. Producing medicine in animal urine has the potential to be more economical than mammary gland "pharming"–the current practice of producing pharmaceuticals in the milk of transgenic animals. ARS scientists say it will be possible to collect urine from livestock within a day or two after the animals are born. This early collection has a major advantage over mammary gland pharming, since it takes two to three years before the female of most farm animal species reaches sexual maturity, gestates and lactates for the first time. Another advantage: Urine can be taken from both males and females. Pharmaceuticals such as human growth hormones, alpha antitrypsin (used for treating emphysema) and lactoferrin (used to treat stomach infections in babies), plus other human medications, have been produced in the milk of transgenic livestock. The researchers stress that the findings are preliminary and that there are drawbacks. For example, scientists note that the bladder produces a much lower concentration of drugs than does the mammary gland. But because purification from urine should be less costly, the low concentration should not pose a major problem. The scientists say this demonstrates that the approach is feasible, but more research is needed to perfect the system.

Gene Evaluation and Mapping Laboratory, Beltsville, MD Robert J. Wall, (301) 504-8362,bwall@ggpl.arsusda.gov /

Black-legged deer ticks could fall prey to a naturally occurring fungus that's been tentatively identified by ARS scientists.The tick, Ixodes scapularis, can infect people with the bacterium responsible for causing Lyme disease. The fungus, a species of Gliocladium, infects the tick and feeds, grows and reproduces inside the pest. Researchers are now exploring Gliocladium's potential as a tick biocontrol. One possibility: spraying a fungal spore preparation along hiking trails, backyards or other high-vegetation areas where ticks and humans cross paths. The tactic would primarily target immature ticks in the late spring and early summer. That's when their cuticle–softer at that early stage of the tick's life– is most easily penetrated by a natural enzyme the fungus produces. The enzyme helps the fungus infect its host. In lab experiments, 70 percent of tick nymphs died after being exposed to spores of the fungus. Immature nymph ticks are most likely to transmit Lyme disease. The ailment, which can be treated early on with antibiotics, causes flu-like symptoms such as fatigue, headache and joint pain. Lyme is a serious health concern in the Northeast and Midwest. It is also spread by another, closely related deer tick species called Ixodes pacificus.

Parasite Biology and Epidemiology Laboratory, Beltsville, MD Patricia Allen, (301) 504-8770, pallen@ggpl.arsusda.gov/