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Wildlife

Several weeks ago, an incident in Idaho with the use of a M-44 device by USDA’s Wildlife Services (WS) led to the hospitalization of a teenager and death a dog, which caused a flurry of sensational news that emphasized the negative impacts of the devices.

Following the incident, WS agreed to temporarily stop the use of M-44 devices in Idaho in response to a petition filed, but the use of the devices is critical in controlling coyotes in 12 states across the West.

“National scrutiny on the use of M-44’s is strong,” says American Sheep Industry (ASI) Executive Director Peter Orwick. “Many animal rights groups have been pushing lawsuits and legislation to ban the tool because they are against lethal removal of predators.”

Using M-44

M-44s are primarily used for coyote damage management, and they are placed along game trails, livestock trails, fence lines and seldom-used ranch roads.

“In addition, the M-44 is registered for the control of communicable disease vectors, such as coyotes that carry rabies,” explains ASI.

They work by ejecting sodium cyanide powder into the mouth of predators. The device is triggered when the animal pulls on the baited M-44 top.

“The sodium cyanide powder reacts with the moisture in the animal’s mouth, which releases hydrogen cyanide gas,” ASI says. “Death occurs from 10 seconds to two minutes after the device is triggered.”

ASI explains that extensive studies have been done to prevent adverse effects to the environment or non-target animals.

“In placing M-44s in the field, WS personnel use their expertise in animal behavior patterns to minimize the risk of attracting non-target animals to the device, they added.

Use in Wyoming

In Wyoming, M-44 devices are permitted for use by licensed private and commercial pesticide applicators, which are certified by the Wyoming Department of Agriculture (WDA).

WDA Predator Management Coordinator Kent Drake explains that there are very few private applicators in the state of Wyoming. The majority of certified applicators are commercial applicators who are independent contract trappers working for county predator board and WS employees.

“WDA has a different label for M-44s than WS does, but all applicators are licensed using the same training program,” Drake says. “We also have inspectors that make sure WDA applicators and WS applicators are conforming to the requirements.”

Mike Foster, WS Wyoming director, says, “We can and do set M-44s on state, Bureau of Land Management (BLM) and private land.”

He notes that currently, requirements for M-44 use include 26 use restrictions, ranging from placement restrictions to training requirements.

“We do not set M-44s in known occupied wolf habitat or in known grizzly bear habitat during the time that the bears are out of their dens,” Foster says. “There  are several counties where we do not use M-44s at all, either because we have no presence in the county or because of conflicts with wolves or grizzly bears make them too hazardous to set them.”

Foster emphasizes that, where threatened and endangered species exist, M-44s are not used.

M-44s have been used in Wyoming since 1974, and a similar device called a Coyote Getter was used before that. As of April 25, 184 devices were in use by WS across the state.

“The number of M-44s in use fluctuates on a regular basis, as trappers set and remove individual devices,” Foster explains. “They are generally most used in the winter months, and during the summer, we generally have no devices set.”

Since Oct. 1, 2014, WS has removed 535 coyotes and 107 red fox using M-44 devices.

Agriculture importance

M-44 devices are important to control predators for the agriculture industry.

“From an agriculture standpoint, M-44s are very beneficial for the protection of cattle and sheep,” Drake says. “Especially this time of year, we’re lambing and calving, and there are many young animals on the ground. It’s critical because predators also have their own young and don’t have as much to eat. This is a high-demand time where we see predators depredate livestock.”

The M-44 devices are also highly selective for canids as a result of the manner and location that they are placed and the bait utilized.

Foster adds that the highly selective nature of M-44s provide an extremely important predator control tool, commenting, “M-44s provide a way to target coyotes, especially during the winter, when they are otherwise difficult to reach.”

“We require applicators to report the number of takes, including unintended losses,” Drake explains. “We see very few unintended losses. In the last eight years, we’ve had a black bear, one wolf and a few ravens.”

When the wolf was killed, an intensive investigation found that the wolf was outside an area of known wolf occupation and the applicator utilized the device according to all rules.

Other benefits

In addition to their effectiveness, Drake says that M-44s leave no residual cyanide in the environment or in the carcass of affected targets.

“The sodium cyanide isn’t residual in the animals,” Drake explains. “It’s only activated by moisture. When the sodium cyanide reacts with moisture, it creates a hydro-cyanic gas, which kills the animal.”

“After the devices go off, the gas dissipates into the environment very quickly,” he continues. “From an environmental standpoint, they’re very safe and not harmful to other wildlife.”

Important device

“M-44s are cost-efficient, simple devices,” Foster emphasizes, “and, when used according to regulations, they are a great asset to any predator control program.”

Orwick comments, “We advise that people visit with their congressional delegations and predator management folks on the state-level about the effectiveness and safety of the M-44.”

“In the dozen states that use the M-44, it is critical for livestock protection,” Orwick emphasizes. “In some states, 30 to 40 percent of coyotes are taken using M-44s.”

Saige Albert is managing editor of the Wyoming Livestock Roundup. Send comments on this article to This email address is being protected from spambots. You need JavaScript enabled to view it..

Controlling horn flies is a given in every beef operation. In fact, with $1 billion in losses in the U.S. each year, it is an area many producers could improve upon.

According to University of Nebraska Entomologist Dave Boxler, cows experience blood loss and annoyance when horn fly populations are high.

Impact of horn flies

This blood-feeding fly also impacts milk production in nursing cows, changes grazing patterns in pasture cattle and horses, causes bunching of animals and decreases weaning weights and yearling weights.

In fact, University of Nebraska studies indicate calf weaning weights could be 10 to 20 pounds heavier when horn flies are controlled on the mother cows. In yearlings, weights can be up to 18 percent higher when some type of horn fly control is managed.

In addition, Boxler said horn flies have been implicated in the spread of summer mastitis.

Damages

The economic injury level (EIL) of the horn fly is 200 flies per animal. They typically feed on the shoulders, back, sides and belly of the animal and can take up to 35 blood meals each day.

“They only leave the animal when the female deposits eggs in fresh cow manure,” Boxler said. “Because of this, horn fly population can reach very high levels – in the thousands during the summer. Horn flies numbers can exceed 5,000 on bulls.”

The best time to evaluate horn fly levels is between 8 and 11 a.m., when they can be found on the top and sides of the animal. During the heat of the day, the flies will move to the belly region.

Controlling the pest

Boxler said if producers have a horn fly problem, there are several methods of control from animal sprays, mist blower sprays, pour-ons and insect growth regulator (IGR) feed-throughs to dust bags, oilers and rubs to ear tags.

The best method of control depends on the management program the producer has in place.

“Pour-ons can cause stress to the animal and offset the benefits,” Boxler said.

If an IGR feed-through is used, the animal must consume a certain amount each day for it to be effective. The IGR can be fed through mineral, mineral blocks or tubs. The IGR kills fly larvae in the manure.

“Proximity to untreated cattle and under-consumption can prevent it from working,” he said.

Dust bags, back rubbers and oilers can be effective ways to control horn flies, but Boxler said they can be 25 to 50 percent less effective when they are used in a free-choice use system.

Other options

Insecticide ear tags can also be effective if two tags are applied to the cattle after June 1. To keep up resistance, Boxler said it is essential for producers to rotate insecticide classes every year to prevent the horn fly from building up resistance to the fly tag.

In an example, he showed using an XP 820 tag in year one, an organophosphate like Corathan in year two and a synthetic pyrethoid like Python in year three.

At the end of the fly season, Boxler said it is important to remove all insecticide ear tags.

The University of Nebraska also conducted a study evaluating the impact of a permethrin pour-on applied at the recommended rate on July 21 and Aug. 21. The first application provided 20 days of fly control and the second 24 days of fly control.

“Basically, the pour-on provided three weeks of fly control at a cost of about $2.16 per animal,” he said.

A relatively new product available to ranchers is a python strip that can be applied behind an existing ear tag. In a 2014 study, Boxler said these strips were applied in June and provided fly control for 15 weeks below economic injury levels.

“No strips or tags were lost, and no adverse affects were observed,” Boxler said. “It reduced the horn fly population 88 percent and cost $3.04 a head for the treatment.”

Face flies prevalent from wet conditions

Face flies don’t surface every year, but during a wet year like this one, they are appearing in numbers. Although they can be found most anyplace, face flies will be more abundant in waterways, canyon floors with trees or shaded vegetation, irrigated pastures and in areas with abundant rainfall.

These fly numbers peak in late July to early August.

According to University of Nebraska Entomologist Dave Boxler, the face fly resembles a house fly, except it is somewhat larger and darker.

“They were introduced to North America in the 1950s on cattle coming from Europe,” he said. “They feed on animal secretions, nectar and dung liquids.”

The female face fly will feed around the eyes, mouth and muzzle causing the animal annoyance. They also feed on wounds and mechanical injuries, he said.

The female face fly can also cause damage to the host’s eye tissue, promoting diseases like pinkeye.

“Face fly control is challenging because these flies feed around the face and spend a significant amount of time off the animal,” Boxler said.

The most effective forms of control are back rubbers/oilers, dust bags, oral larvicides and IGR feedthroughs and insecticide ear tags.

“Ear tags will need to be applied to both the cow and the calf,” Boxler said. “The best control of face flies is daily control.”

 

Gayle Smith is a correspondent for the Wyoming Livestock Roundup. Send comments on this article to This email address is being protected from spambots. You need JavaScript enabled to view it..

WildEarth Guardians, an environmental activist group, claimed a win over Wildlife Services when the Ninth Circuit Court of Appeals confirmed that WildEarth Guardians’ interests are injured by the program’s activities.

However, Peter Orwick, executive director of the American Sheep Industry Association, says their statements were embellished on the success of the suit.

“WildEarth Guardians are just rabid opponents of Wildlife Services,” he says. “They oppose the program, and they put out an incredibly misleading press release on the court actions in Nevada.”

Court ruling

The Ninth Circuit Court ruling, Orwick explains, referred to National Environmental Policy Act (NEPA) documents that referenced a Programmatic Environmental Impact Statement (PEIS) from 1994.

In an Oct. 12 statement, Wildlife Services Deputy Administrator William Clay said, “In the 21 years since the PEIS Record of Decision was issued, Wildlife Services has initiated the phase-out of any reliance on the 1994 PEIS. Today, most Wildlife Services NEPA documents are not tiered to the PEIS. No new Wildlife Services NEPA documents signed after the date of this notice will be tiered to the 1994 PEIS.”

Clay added, “In the future, Wildlife Services intends to revise or redo all of its NEPA documents that are currently tiered to the 1994 PEIS.”

Orwick comments, “To my knowledge, that was the only reference to the 1994 PEIS,” he says. “That PEIS was a big deal, but it’s well over 20 years old now, and now, instead of doing a national EIS like the 1994 one, Wildlife Services is doing site-specific EIS’ that go by district, state or site to manage their wildlife mitigation and control.”

“WildEarth Guardians took Wildlife Service to court, and the court said they needed to update the EIS,” Orwick adds. “Wildlife Services said, ‘Of course. We’re updating it now, just as we have all over the country.’”

Site specific work

Wildlife Services has been working for the last several years to conduct site-specific, state-specific or area-specific EIS documents for their activities.

“Despite what WildEarth Guardians said in their press release, they just happened to find one of the rare documents that was addressed,” he says. “Wildlife Services has assured us that they continually update their NEPA documents.”

Orwick continues, “In my opinion, the folks who work on NEPA at Wildlife Services are probably some of the best in the federal government. They have over 25 years of experience, and I’m impressed with the work they do.”

Orwick also notes that Wildlife Services is very beneficial for producers who run on federal lands, as well, by providing the NEPA documents that allow grazers to use predator control, as well.

“The agency does the NEPA, which allows individuals to use grazing permits with predator control,” he explains. “That makes their work doubly important for ranchers.”

“It is discouraging to read that WildEarth Guardians is portraying this ruling as prohibiting work on public lands when in reality the only area in Nevada that is not active is some wilderness area,” Orwick says. Orwick adds that he anticipates there was no predator work for livestock producers on wilderness anyway.

On the ground

In Wyoming, Wildlife Services updated their EIS in 2015, and Amy Hendrickson, Wyoming Wool Growers Association executive director, says, “Predators are certainly a very significant part of the losses that producers have, in addition to death loss from disease and other causes.”

Hendrickson continues, “In 2015, predator losses were down to just under five percent, but they have been as high as 10 percent. No business can stay in production if they are taking a 10 percent loss. It just can’t be sustained.”

Wildlife Services helps producers to control predator populations, including coyotes, wolves, ravens and foxes.

“We lease our two airplanes to Wildlife Services to use in controlling coyotes and other predators,” Hendrickson explains. “Wildlife Services is also the only agency that can help with wolf depredation. They are the only agency who can take a wolf once it is verified that the wolf is the cause of livestock loss.”

Losses

“Predators are the number two biggest expense in the sheep industry as a whole,” Orwick mentions. “We do everything we can to control predators.”

He adds, “It doesn’t matter where we run livestock today, ranchers deal with some wildlife issue. It’s a constant almost nationwide anymore.”

A decrease in death loss to predators from 10 down to five percent in Wyoming is largely attributable to the work of Wildlife Services, as well as predator management districts and the Wyoming Animal Damage Management Board (ADMB). 

Hendrickson adds that when she visits with people who have formerly raised sheep, one of the reasons they exited the industry was because of predator losses.

“A lot of times when I talk to people, they say, ‘We had sheep, but the predators just killed me. I couldn’t stay in business,’” she explains. “Many people cite predators as the reason they are no longer in the sheep business.”

More benefits

“We also have to remember that is isn’t just the livestock that benefit from the work of Wildlife Services,” Hendrickson says. “Wildlife benefit, as well. Control of coyotes and wolves helps our mule deer, antelope, elk and sage grouse populations, as well. It is very important to our state to be able to control predators.”

She adds, “We don’t want to wipe out wolves, coyotes or other predators. We just want to maintain a good balance.”

Saige Albert is managing editor of the Wyoming Livestock Roundup and can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it.

 

WildEarth Guardians, an environmental activist group, claimed a win over Wildlife Services when the Ninth Circuit Court of Appeals confirmed that WildEarth Guardians’ interests are injured by the program’s activities.

However, Peter Orwick, executive director of the American Sheep Industry Association, says their statements were embellished on the success of the suit.

“WildEarth Guardians are just rabid opponents of Wildlife Services,” he says. “They oppose the program, and they put out an incredibly misleading press release on the court actions in Nevada.”

Court ruling

The Ninth Circuit Court ruling, Orwick explains, referred to National Environmental Policy Act (NEPA) documents that referenced a Programmatic Environmental Impact Statement (PEIS) from 1994.

In an Oct. 12 statement, Wildlife Services Deputy Administrator William Clay said, “In the 21 years since the PEIS Record of Decision was issued, Wildlife Services has initiated the phase-out of any reliance on the 1994 PEIS. Today, most Wildlife Services NEPA documents are not tiered to the PEIS. No new Wildlife Services NEPA documents signed after the date of this notice will be tiered to the 1994 PEIS.”

Clay added, “In the future, Wildlife Services intends to revise or redo all of its NEPA documents that are currently tiered to the 1994 PEIS.”

Orwick comments, “To my knowledge, that was the only reference to the 1994 PEIS,” he says. “That PEIS was a big deal, but it’s well over 20 years old now, and now, instead of doing a national EIS like the 1994 one, Wildlife Services is doing site-specific EIS’ that go by district, state or site to manage their wildlife mitigation and control.”

“WildEarth Guardians took Wildlife Service to court, and the court said they needed to update the EIS,” Orwick adds. “Wildlife Services said, ‘Of course. We’re updating it now, just as we have all over the country.’”

Site specific work

Wildlife Services has been working for the last several years to conduct site-specific, state-specific or area-specific EIS documents for their activities.

“Despite what WildEarth Guardians said in their press release, they just happened to find one of the rare documents that was addressed,” he says. “Wildlife Services has assured us that they continually update their NEPA documents.”

Orwick continues, “In my opinion, the folks who work on NEPA at Wildlife Services are probably some of the best in the federal government. They have over 25 years of experience, and I’m impressed with the work they do.”

Orwick also notes that Wildlife Services is very beneficial for producers who run on federal lands, as well, by providing the NEPA documents that allow grazers to use predator control, as well.

“The agency does the NEPA, which allows individuals to use grazing permits with predator control,” he explains. “That makes their work doubly important for ranchers.”

“It is discouraging to read that WildEarth Guardians is portraying this ruling as prohibiting work on public lands when in reality the only area in Nevada that is not active is some wilderness area,” Orwick says. Orwick adds that he anticipates there was no predator work for livestock producers on wilderness anyway.

On the ground

In Wyoming, Wildlife Services updated their EIS in 2015, and Amy Hendrickson, Wyoming Wool Growers Association executive director, says, “Predators are certainly a very significant part of the losses that producers have, in addition to death loss from disease and other causes.”

Hendrickson continues, “In 2015, predator losses were down to just under five percent, but they have been as high as 10 percent. No business can stay in production if they are taking a 10 percent loss. It just can’t be sustained.”

Wildlife Services helps producers to control predator populations, including coyotes, wolves, ravens and foxes.

“We lease our two airplanes to Wildlife Services to use in controlling coyotes and other predators,” Hendrickson explains. “Wildlife Services is also the only agency that can help with wolf depredation. They are the only agency who can take a wolf once it is verified that the wolf is the cause of livestock loss.”

Losses

“Predators are the number two biggest expense in the sheep industry as a whole,” Orwick mentions. “We do everything we can to control predators.”

He adds, “It doesn’t matter where we run livestock today, ranchers deal with some wildlife issue. It’s a constant almost nationwide anymore.”

A decrease in death loss to predators from 10 down to five percent in Wyoming is largely attributable to the work of Wildlife Services, as well as predator management districts and the Wyoming Animal Damage Management Board (ADMB). 

Hendrickson adds that when she visits with people who have formerly raised sheep, one of the reasons they exited the industry was because of predator losses.

“A lot of times when I talk to people, they say, ‘We had sheep, but the predators just killed me. I couldn’t stay in business,’” she explains. “Many people cite predators as the reason they are no longer in the sheep business.”

More benefits

“We also have to remember that is isn’t just the livestock that benefit from the work of Wildlife Services,” Hendrickson says. “Wildlife benefit, as well. Control of coyotes and wolves helps our mule deer, antelope, elk and sage grouse populations, as well. It is very important to our state to be able to control predators.”

She adds, “We don’t want to wipe out wolves, coyotes or other predators. We just want to maintain a good balance.”

Saige Albert is managing editor of the Wyoming Livestock Roundup and can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it.

 

Casper – At Washington State University (WSU) in Pullman, Wash., Subramaniam Srikumaran has continued his focused research on pneumonia in wild sheep, and recent research has shown which bacteria causes the disease, and may yield a vaccine to prevent wild sheep die-offs as a result.
    “Dr. Srikumaran is doing cutting edge research related to the domestic sheep/bighorn sheep question,” explained Wyoming Wild Sheep Foundation Executive Director Kevin Hurley at the 2012 Wyoming Wild Sheep Annual Convention in Casper on June 2, where Srikumaran, known as Dr. Sri, presented his latest findings.
    Srikumaran, is a professor at WSU and holds the Rocky Crate Foundation for North American Wild Sheep Endowed Chair.
Finding the enemy
    Sri noted that there are several bacterial species that have been identified in the lungs of deceased bighorn sheep, but he said it is important to identify the bacteria primarily responsible for causing disease.
    “The bacteria that have been isolated and detected in pneumonia lungs are Mannheimia haemolytica, Bibersteinia trehalosi, Pasteurella multocida and Mycoplasma ovipneumoniae, but which of these gives the kiss of death?” asked Sri. “If you look at the pneumonic lungs, we asked which bacterium could cause lesions, breakdown of the alveoli wall and kill the white blood cells.”
    For a microorganism to be accepted as a pathogen, Sri mentioned that a series of qualifications, called Koch’s Postulates, must be met. Organisms must be isolated from the sick animal, be cultured in pure form, and the purified culture should cause disease in healthy animals. The organism should be also be re-isolated from the sickened animals.
    “Isolation does not mean an organism causes disease,” clarified Sri, “and failure to isolate an organism from a sick or dead animal does not mean that it does not cause disease.”
    Based on the virulence factors of the bacteria, Sri said research has indicated the Mannheimia haemolytica consistently kills bighorn sheep.
    “When we put bacteria in the lungs, 100 percent of the animals die in 48 hours,” he explained. “Most importantly, M. haemolytica secretes a toxin that kills the white blood cells of the host, called a leukotoxin.”
Friendly fire
    Leukotoxins cause white blood cells, called PMNs, to self-destroy, in turn causing damage to the bighorn sheep.
    “A cell called PMN is the most important cellular defense agent in a host organism because it will swallow bacteria,” explained Sri. “PMNs have a granule containing toxic material.”
    After engulfing bacteria, PMNs release the toxic material, killing the bacteria and themselves.
    However, leukotoxins bind to PMNs and kill them, causing the release of the toxin-filled granules, which in turn cause damage to the host, in this case, bighorn sheep.
    “You could call it friendly fire,” he adds. “The acute inflammation and lung injury are caused by toxic substances released by white blood cells.”
The culprit
    Despite all the signs pointing toward M. haemolytica, Sri mentioned culture methods failed to isolate the bacteria in pneumonic lungs.
    “From the die-off that occurred in 2009/10, from the samples from Montana, M. haemolytica was isolated from only one out of 100 animals. From Nevada, out of 15 animals, only two had M. haemolytica, and from the state of Washington, out of 29 animals, they were able to isolate it from one,” said Sri. “That led some people to believe that maybe we were missing the agent causing death.”
    But the answer wasn’t that simple. Sri and his team then asked why M. haemolytica was the only organism causing death in experimental conditions, but was isolated less frequently in samples.
    “When we cultured M. haemolytica and B. trehalosi together, B. trehalosi grew uninhibited, whereas the M. haemolytica started to go down in numbers as early as six hours and was undetectable by 24 hours,” he explained.
    Additionally, more sensitive tests from the samples that had previously shown no presence of M. haemolytica saw that 91 percent of the samples had the leukotoxin secreted by M. haemolytica present.
    “Only 2.2 percent of healthy animals had toxin-positive M. haemolytica,” said Sri. “This is the most important organism that causes bighorn sheep pneumonia.”
    Other organisms did not have the full potential to result in the deaths of bighorn sheep, as was shown in lab trials.
    “P. multocida does not possess the virulence factors that causes lesions in the lungs,” he said, explaining that the organism would not be responsible as a result. “M. ovipneumoniae alone cannot cause fatal pneumonia. Two out of two lambs did not die when inoculated with the bacterium. It can increase the spread and severity of M. haemolytica-caused pneumonia, but it is not a necessary predisposing agent.”
    Continued research with M. haemolytica and B. trehalosi showed the leukotoxin secreted by bacteria is the main factor in bighorn sheep death.
    “Most bighorn sheep do not carry M. haemolytica. If they do carry it, they carry leukotoxin negative strains,” he added.
Developing a solution
    “The question is, what can we do?” asked Sri. “Spatial separation of domestic sheep and bighorn sheep works because we can prevent the transmission of M. haemolytica, or we can attempt to vaccinate the bighorn sheep.”
    Researchers are working on a vaccination for bighorn sheep that would be given nasally or in feed and would also be transmitted between the wild sheep, but, thus far, results have been unsuccessful.
    “One approach that is more promising uses a harmless virus that carries a non-lethal copy of the leukotoxin,” explained Sri. “The expectation is that, if we give it to a few bighorn sheep, the virus will be transmitted so they get vaccinated.”
    However, because of the difficultly of vaccinating wild animals, Sri’s team is looking at eliminating the organism in domestic animals or minimizing the shedding of M. haemolytica to reduce transmission.
    “Remember, we have showed that the bacteria B. trehalosi can inhibit growth of M. haemolytica. Can we use this property to our advantage?” he asked.
    Research is underway to see if domestic sheep could be inoculated with B. trehalosi, which would eliminate the toxin-producing bacteria.
    “We have done some experiments, and the results are very encouraging,” Sri commented. “After inoculation, we couldn’t detect any M. haemolytica in the nasal secretion.”
    Additionally, research is being pursued to elucidate the mechanism by which B. trehalosi inhibits M. haemolytica.
    “If we know what is inhibiting the M. haemolytica, we can genetically engineer B. trehalosi to produce more of the killer protein to enhance the inhibitory effect,” he said.
    With the difficult of developing vaccines, testing them and getting the permissions to use the vaccines, Sri noted that it would take time.
    “This type of vaccine takes a long time to develop,” he said. “I won’t have a vaccine in the next five years. We should be able to do it in less than 20, but not in five.”
    Saige Albert is editor of the Wyoming Livestock Roundup and can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..

Sri verifies disease transmission
    In continuing his research to solve the problems in bighorn sheep and domestic sheep interactions, Washington State University professor Subramaniam Srikumaran, known as Dr. Sri, needed to document transmission of M. haemolytica from domestic sheep to bighorn sheep.
    “There have been anecdotal reports of die-offs following contact with domestic sheep, which prompted commingling studies,” Sri explained at a June 2 lecture in Casper. “These studies failed to convince everyone that domestic sheep transmitted pathogens, because they did not show conclusively that the pathogens were acquired from domestic animals.”
    To attempt to irrefutably prove transmission, Sri and his research team developed a strategy to tag bacteria from domestic sheep with a marker.
    M. haemolytica from domestic sheep were genetically modified to express a green fluorescent protein (GFP) and resistance to the antibiotic ampicillin. Four domestic sheep were inoculated with the tagged bacteria.
    “We kept the four animals 30 feet away from four bighorn sheep, which were shown to be negative for M. haemolytica,” said Sri. “Nothing happened to the animals. We then allowed fenceline contact through a chain link fence.”
    Following fenceline contact, he noted that two of the bighorn sheep exhibited colonization of the GFP tagged bacteria in their nasal pharynx, coughing and nasal discharge.
    “Then we allowed commingling. Within two days, one died. Three days later, two more died, and the last died after nine days,” he mentioned, noting that the GFP-tagged organisms were isolated from the bighorn sheep. “This is irrefutably proves that domestic sheep can transmit disease.”
    However, Sri clarified, “This study was not performed to point fingers at domestic sheep, but to determine conclusively whether there is transmission of M. haemolytica.”
    This study was published in the Journal of Wildlife Diseases in July 2010.