|
**************************

Support U.S. Agriculture!!!!!!
The window/bumper
decal above is free. Just send us an email of where to send one or more.
ggatley@sprynet.com
***************************
RESEARCH IN
AGRICULTURE
REPORTS
Researchers Help
Cattle Breeders Optimize Profit and
Desired Beef
Traits
Tender steaks start with cattle breeders who
carefully document numerous characteristics of their animals. They use
this information to breed those animals with the “best”
combination of desired traits.
However, “best” has been a subjective and
inconsistent measure, according to Agricultural
Research Service geneticist Michael MacNeil. That slowed
producers’ ability to breed improved animals. Now, thanks to ARS
research, breeders may refine their decision-making by focusing on
profitability.
MacNeil works at ARS’ Fort Keogh Livestock and
Range Research Laboratory in Miles City, Mont. ARS is the chief
scientific agency of the U.S.
Department of Agriculture.
To assess their animals, breeders keep track of
growth traits, such as weights at birth, weaning, and yearling ages
and at maturity. They also measure carcass traits such as marbling and
fat content that are indicators of value to consumers. In addition,
they record traits like the age when a female reaches puberty, and her
pregnancy rate.
Breed associations take the information, combine
it with each animal's genetic tree and run it through a computer
program to develop an expected progeny difference, or EPD. That lets
breeders compare individual animals for individual traits. They would
know, for example, that cow A was more likely to produce offspring
with the desired marbling than cow B.
But the process is not complete. Producers were
left with the difficult task of combining the EPDs in an efficient
manner. So MacNeil is improving the performance testing process by
using the EPDs to predict genetic potential for profit. With his
system, breeders will be able to know how to trade off changes in fat
thickness and marbling, for example, most profitably.
Breeders would also be able to rank animals more
effectively. If there were 100 bulls for sale, breeders could rank
them numerically to find the best bull for their purposes.
The complicated calculations are not yet
available in a simple computer program for individuals to use.
Producers will most likely get the information through Cooperative
Extension Service specialists or breed associations as the lab passes
on the technology.
This research is reported in the December issue
of Agricultural Research
magazine. Click here
to read about it online.
Scientific contact: Michael D. MacNeil, ARS Fort
Keogh Livestock and Range Research Laboratory, Miles City, Mont.,
phone (406) 232-8213, fax (406) 232-8209, mike@larrl.ars.usda.gov.
|
|

Fire ants have been found to be the most
ecologically dominant species in their environment, according to a
new ARS study. Photo courtesy of Pest and Diseases Image Library,
Bugwood.org.
|
Fire Ant Out Competes
Other Species—
Even in its Native
Habitat
Even in its native Argentina, the fire ant wins in
head-to-head competition with other ant species more than three-quarters
of the time, according to Agricultural
Research Service (ARS) scientists.
ARS scientists at the South
American Biological Control Laboratory (SABCL) in Hurlingham,
Argentina, have been studying how different ant species fare against the
fire ant as part of an effort to learn more about the behavior of this
pest—an invasive species in its non-native United States.
Fire ants often attack in swarms--not only causing
painful stings to humans, but can even kill small animals. Little has been
known, however, about the fire ant's competitive nature or how it
interacts with other ants.
SABCL biologist Luis Calcaterra, working closely with
lab director Juan
Briano, has been studying interactions between the red imported fire
ant, Solenopsis invicta, and other aboveground foraging ants in two
habitats in northeastern Argentina—using a combination of pitfall traps
and baits to study day-to-day activity in ant communities.
The pitfall trap is a 50 milliliter plastic tube
buried in the ground and half-filled with soapy water. The bait is one
gram of canned tuna placed on a plastic card measuring five centimeters in
diameter. The trap and bait gave the scientists a way to determine ant
populations at the sites, and showed the dominance of each species.
Some 28 ant species coexisted with S. invicta
in an open area of forest growing along a watercourse, whereas only 10
species coexisted with S. invicta in the dry forest grassland. The
researchers found that the fire ants had the highest numbers in the open
forest area along the watercourse.
Prior to these studies, it was thought that the fire
ant—now established throughout the Americas—was not dominant in its
native land. But the studies showed that the fire ants were the most
ecologically dominant, winning 78 percent of the interactions with other
ants, mostly against its most frequent competitor, the South American
big-headed ant, Pheidole obscurithorax, an ant of northern
Argentina and Paraguay also introduced in the United States. And in
battles with the invasive Argentine ant, Linepithema humile, the
fire ants were even more dominant, winning out 80 percent of the time.
This study was published in Oecologia,
a journal that deals with plant and animal ecology.
ARS is the principal intramural scientific research
agency of the U.S. Department of
Agriculture.
|

ARS scientists have developed a new bait that may help control
varroa mites, the top pest of honey bees. Click the image for
more information about it.
|
New Bait
Lures Varroa Mite
to its Doom
Varroa mites could literally
be walking into a trap—thanks to a new attractant developed by Agricultural
Research Service (ARS) scientists in Gainesville, Fla.
The 1/16-inch long parasite, Varroa
destructor, is a top pest of honey bees nationwide, hindering the
beneficial insects' ability to pollinate almonds, blueberries, apples,
zucchini and many other flowering crops.
At the ARS Chemistry
Research Unit in Gainesville, research leader Peter
Teal and colleagues are testing a bait-and-kill approach using
sticky boards and natural chemical attractants called semiochemicals.
In nature, Varroa mites rely
on these semiochemicals to locate—and then feed on—the bloodlike
hemolymph of both adult honey bees and their brood. Severe infestations
can decimate an affected hive within several months—and rob the
beekeeper of profits from honey or pollinating services. But in this
case, the mites encounter a more heady bouquet of honey bee odors that
lure the parasites away from their intended hosts and onto the sticky
boards, where they starve.
In preliminary tests, 35 to 50
percent of mites dropped off the bees when exposed to the attractants.
Free-roving mites found the semiochemicals even more attractive,
according to Teal.
Moreover, the extra dose of
semiochemicals wafting through hives didn't appear to significantly
interfere with the honey bees' normal behavior or activity, added Teal
who, along with postdoctoral associate Adrian
Duehl and University of Florida
collaborator Mark Carroll, reported the results this past January at the
2009 North American Beekeeping
Conference in Reno, Nev.
The team hopes ARS' patenting of
the Varroa mite attractants will encourage an industrial partner
to develop the technology further.
ARS is the principal intramural
scientific research agency of the U.S.
Department of Agriculture.
|

It may not always pay for ranchers to use herbicides
to kill exotic invasive weeds on the range, according
to a new study. Click the image for more
information about it.
|
Spraying
Herbicide on Invasive Weeds
Doesn't
Always Pay, Study Shows
It may not always pay for
ranchers to use herbicides to kill exotic invasive weeds such
as leafy spurge, according to a 16-year study by the Agricultural
Research Service (ARS) and colleagues.
Rangeland ecologist Matt
Rinella at the ARS Fort
Keogh Livestock and Range Research Laboratory in Miles
City, MT, and colleagues conducted the study. Data they
collected 16 years after a one-time aerial spraying of
herbicide showed that the invasive leafy spurge (Euphorbia
esula L) may have ultimately increased due to spraying.
Conversely, several desirable native forbs were still
suffering the effects of spraying 16 years after spraying.
Although the herbicide
would have dissipated within a few years, it seemed to cause a
long-term plant community shift.
Any increase in grass
production from the herbicide spraying only lasted a year or
two.
The study was done on the
N-Bar Ranch in Montana. Each plot was either grazed and
sprayed, grazed but not sprayed, not grazed but sprayed or not
grazed or sprayed. Cattle grazing helped maintain native plant
numbers when herbicide was used.
Cattle grazing can help
native forbs thrive because cattle prefer grasses over forbs,
and cattle trample soil, loosening soil for seeds that the
animals inadvertently plant when seeds are caught in their
hooves or fur. That said, when herbicide wasn't used, most
native forbs did as well with or without cattle grazing.
Herbicide caused the
native plants Missouri goldenrod and yarrow to become rarer
over the 16-year study period. Barring herbicides, these two
species proved capable of co-existing indefinitely with the
exotics.
Four native perennials
became rarer in sprayed plots, but only when grazing was
excluded: velvety goldenrod, white prairie aster, vetch, and
prairie sagewort. Herbicide spraying caused no long-term harm
to four other native perennials. Rockjasmine and other plants
belonging to the Androsace spp. group were not affected
by the herbicide even initially.
The study suggests that
applying herbicides over large areas of land containing
herbicide-sensitive native plants is sometimes ill-advised.
The research was
published in the journal Ecological
Applications.
ARS is the principal
intramural scientific research agency in the U.S.
Department of Agriculture.
|
|

New research is shedding light on how endophytic fungus-infected
fescue causes fescue toxicosis--a disease that affects grazing
animals and costs the U.S. cattle industry an estimated $600
million annually. Click the image for more information about
it.
|
Connecting the Dots
for
Alkaloids, Toxicosis Symptoms
New research from Agricultural
Research Service (ARS) scientists and their university colleagues is
shedding light on the relationship between chemical compounds and fescue
toxicosis—a disease that affects grazing animals and costs the U.S.
cattle industry an estimated $600 million annually.
Fescue toxicosis is a major problem
for producers whose herds graze on tall fescue. A major forage grass in
many states, tall fescue can cause toxicosis in cattle and other
ruminants if it's infected with endophytic fungus. The disease causes
lameness and reduced production efficiency, and can even be fatal if
infected animals are subjected to stressful situations, such as extreme
heat or long-distance transport.
Scientists believe many symptoms of
toxicosis are caused by chemical compounds known as ergot alkaloids, but
much is still unknown about how they cause clinical signs to develop.
Led by ARS animal scientist James
Klotz, scientists at the ARS Forage
Animal Production Research Unit in Lexington, Ky., and the University
of Kentucky are investigating the physiological responses of
ruminants to tall fescue alkaloids.
One sign of toxicosis is a
narrowing of blood vessels. Using a model that predicts changes in blood
flow in the limbs of cattle, Klotz and his colleagues examined the
influence of specific alkaloids—both individually and in combination.
Of the three alkaloids tested,
ergovaline was the most effective at making the veins contract. The
others, N-acetylloline and lysergic acid, had little effect on vein
contraction. The results also showed that combining two alkaloids did
not increase the toxicity of either—at least in terms of vein
contraction.
Further research is underway to
determine how these alkaloids influence other tissues, organs and
physiological systems. In one study, the scientists showed that
ergovaline, but not lysergic acid, can bioaccumulate in vitro,
suggesting that ergovaline may be more likely to induce toxicosis.
Research like this is essential for
understanding exactly how endophyte-infected tall fescue influences
grazing animals. Eventually, this information could help scientists
determine which compounds are most toxic and how to protect cattle from
them.
These studies were published in the
Journal of Animal Science.
ARS is the principal intramural
scientific research agency for the U.S.
Department of Agriculture.
|

ARS hydraulic engineers are helping the Natural Resources
Conservation Service rehabilitate aging small dams across the
country by increasing their utility and safety with roller compacted
concrete stepped spillways. Photo courtesy of NRCS.
|
New Designs for Making Old
Dams Safer
A group of Agricultural
Research Service (ARS) hydraulic engineers are helping to rehabilitate
aging small dams across the country.
Efforts are underway to upgrade existing
auxiliary spillways or build new spillways for these dams, especially in
Oklahoma. These upgraded or new spillways meet current dam safety standards
and will increase the useful lives of the dams.
The U.S.
Department of Agriculture's Natural
Resources Conservation Service (NRCS) has helped build more than 11,000
earthen dams over the years as part of its Watershed
Protection and Flood Prevention Operations Program. These dams serve
many purposes, but the primary purpose is flood control. Since the program
began in 1944, ARS
Hydraulic Engineering Research Unit (HERU) engineers in Stillwater,
Okla., have partnered with NRCS in the development of design standards for
the dams.
When ARS hydraulic engineer Sherry
L. Hunt and her colleagues were asked recently by NRCS to help evaluate
and design retrofitted Roller Compacted Concrete (RCC) stepped spillways for
dams in Georgia and North Dakota, they found the same technology also can
help increase flow capacity on many of these dams across the country. So
they developed generalized criteria for designs that could be used anywhere
in the country.
Compacting concrete with a roller is a
fast way to make a tough surface.
With the many changes that have occurred
over the years—including deterioration, changes in upstream and downstream
land use and population, and changes in dam safety laws—the research by
the HERU engineers with this technology is once again helping NRCS, which
has the lead for design and construction of these earthen dams.
The ARS engineers conduct model studies
both indoors at small scales and also outdoors at large scales. This summer
Hunt will begin using a large-scale flume outdoors that is the actual size
of the RCC spillways being designed for these dams. ARS engineers will use
the data from the water flow on their experimental spillways to develop
design and construction guidelines.
ARS is the principal intramural scientific
research agency in USDA.
|

An assay created by
Agricultural Research Service chemist Charles C. Lee and
colleagues provides a faster, less expensive way to discover
genes that make an enzyme that can help ferment cellulose into
biofuel. Click the image for more information about it.
|
New Test Corners
Elusive Biofuels Enzyme
In a wood near you, powerful
microbes quicken the decay of fallen tree branches. These adroit
decomposers perform that essential role by producing specialized
enzymes. In the United States and abroad, biofuels researchers prize
these enzymes because they may speed and simplify the process of making
bioethanol, and coproducts, from the cellulose in the cell walls of
energy crops such as switchgrass.
One of the most sought-after of
those specialty enzymes may now be easier for today's researchers to
find. That's thanks to an assay created by Agricultural
Research Service (ARS) chemist Charles
C. Lee and colleagues at the agency's Western
Regional Research Center in Albany, Calif.
High-speed and high-tech, but
surprisingly affordable, the sophisticated assay equips scientists with
a faster, less expensive way to discover genes that enable microbes to
make an enzyme known as an alpha-glucuronidase. In nature, this enzyme
cleaves glucuronic acid from hemicellulose and, in so doing, helps
disassemble plant cell walls. Hemicellulose, cellulose and lignin are
bound in a tight, complicated matrix that impedes other enzymes' ready
access to the cellulosic sugars that are ideal for fermenting into
bioethanol.
Right now, there are very few genes
in the publicly available GenBank
database that code for alpha-glucuronidases. The new assay, however, may
change that by making it possible for scientists to quickly screen the
genes in masses of anonymous microbes taken from the forest floor,
compost heaps, or other outdoor places where decomposers live and work.
In brief, the test involves moving
the DNA from the outdoor microbes into laboratory bacteria that, in
petri dishes, will form telltale dark spots if they have alpha-glucuronidase
genes and enzymes actively working inside. Scientists can then isolate
and copy the genes from those bacteria, and perhaps re-tool the genes to
make them even stronger and faster-acting, for tomorrow's biorefineries.
Lee developed the assay with Albany
colleague Kurt
Wagschal, patterning it upon an assay Wagschal built earlier for
finding another in-demand biofuels enzyme. Lee also worked with Dominic
W.S. Wong, George
Robertson, William
Orts, and Rena
Kibblewhite. All are with the Bioproduct
Chemistry and Engineering Research Unit at Albany.
ARS is the principal intramural
scientific research agency of the U.S.
Department of Agriculture.
|