Convention: PERC Hears from Researchers

PERC Hears from Researchers

Special to the Sheep Industry News

The Production Education and Research Council session at the ASI Annual Convention was packed full of research information from important sheep industry collaborators.

Don Knowles, Ph.D., and Maggie Highland, Ph.D., of USDA Agricultural Research Service Animal Disease Research Unit gave an update on Mycoplasma ovis research, noting that M. ovis lives on the surface of red blood cells and has a worldwide distribution in ungulate populations such as domestic sheep and goats, deer and reindeer. It is transmitted via biting insects and ticks, reuse of needles and transplacental transmission. Reports of infection and disease are rare in the United States, but further study is needed.

Clinical symptoms of M. ovis infection include jaundice with or without red urine, weight loss, lack of thrift and bottle jaw. Its symptoms can resemble that of barber pole worm infestation or a vitamin/mineral deficiency. But since infected animals might not show readily observable symptoms, researchers are unsure of the consequence of M. ovis, at least in America. ARS’s current work is probing the distribution and prevalence of M. ovis in the United States, and the operational impacts on its prevalence.

One project examined blood samples collected through the National Animal Health Monitoring System from 2001 and 2011, finding that M. ovis is a widespread bacterium in U.S. domestic sheep, with 20 to 38 percent of samples testing positive. In addition, the ARS team will study M. ovis seasonal infection prevalence, effects on productivity and maternal transmission through a joint project with the U.S. Sheep Experiment Station in Dubois, Idaho. This project examines effects on average daily weight gain, as well as the lifetime production of ewes. ARS will also look for any link to jaundice condemnation of carcasses; whether there is a value in ewes having a low level of infection as a method of passing on immunity; and the effect of flock size and operation type on prevalence.

Highland also talked about the continued research on the respiratory disease complex in bighorn and domestic sheep, Mycoplasma ovipneumoniae (Movi), noting that pneumonia in lambs is extremely complex and relates to both management practices and infectious agents.

“Diseases are not transmitted,” Highland said. “Infectious agents are transmitted. Disease is the outcome of that transmission,” and is dependent on the animal (sheep); the bug (Movi); and the burden (stressors).

“If you’re not looking at all three,” Highland said, “I don’t think you’ll ever come close to understanding the disease.”

Movi was discovered in the last decade to be highly associated with the complex phenomenon of bighorn sheep pneumonia, impacting both adults and lambs. It has been known for decades to be associated with domestic sheep and goat pneumonia, often associated with suboptimal environmental conditions. This bacterium is endemic in the U.S. domestic sheep population, from coast to coast, and can cause unthrifty lambs.

The Animal Disease Research Unit has several major research projects underway that deal with Movi, including one on host genetics of infection and shedding of Movi in domestic and bighorn sheep; and another assessing innate and adaptive immune factors associated with susceptibility of domestic and bighorn sheep to Movi; as well as eventual potential vaccine development.

Highland has also been involved in testing pack goats for Movi throughout the western states in response to pressure to eliminate pack goats because they may pass Movi to bighorns. Nasal swabs from the goats were sent to both an independent laboratory and to the ADRU lab. Detection of Movi did not occur in the majority of samples, but a few goats had a positive response. Several of the positives were from kids less than 12 weeks old, and subsequent testing failed to detect Movi. Overall findings indicate a really low prevalence rate of Movi in the tested goats.

J. Bret Taylor, Ph.D., of the U.S. Sheep Experiment Station, reported that as the result of responses received during its stakeholder listening sessions, the station is in the process of converting its flock to an industry flock, and will move all its relevant data to the NSIP program (starting with Rambouillets, then Targhees, then Polypays and Suffolks). The station also plans to develop a wool-value subindex and/or increase precision of lifetime ewe production indexes.

Taylor reported another program goal is to describe the ecological benefit of sheep grazing on management and maintenance of sage grouse habitat – an important issue in the western United States. Much of the future sheep station efforts will focus on flock health, including developing antibiotic alternatives for management of diseases in pregnant and lactating ewes and neonatal lambs.

Larry Clark, Ph.D., of the USDA/APHIS National Wildlife Research Center, reported on promising research being conducted with sodium nitrate for feral pig control. Research indicates the time to death is one to two hours, and the level of awareness (a measure of humaneness) is low. Sheep producers should be interested in this research project because it does have potential for use in coyote control. The project is about to begin its field trials, and results will be reviewed by the Environmental Protection Agency.

Julie Young, also with the National Wildlife Research Center, reported that four years of field work assessing the effectiveness of various livestock guardian dog breeds is now complete, so analysis can begin. The project looked at the effectiveness of various breeds in protecting sheep from wolves and grizzly bears, including Kangals, Karakachans, and Cao de Gado Transmontano (Transmontano mastiff). These breeds were compared to the big white guardian dogs (such as Great Pyrenees, Akbash, etc.) that are more common on the landscape today. Behavioral data on the dogs was gathered via focal sampling and simulations.

One project involved placing a wolf decoy in a location where it could be watched remotely as a call box was used to call the dogs in. A similar project involved using an elk hide and an elk call to see how the dogs responded to other wildlife.

All three breeds were more vigilant to the wolf than to the deer. The white dogs and Transmontanos displayed more investigatory behavior toward the wolf (than the other breeds).

Researchers looked at posture in the dogs – did they actually get up and do something? They found Kangal and Karakachan responded more to stimuli. Karakachan were two-times more likely to respond than the white dogs.

As for maintaining their proximity to the sheep flock, the Karakachan were more likely to attend to the sheep, while the Transmontano were more likely to attend to the wolf decoy. All comparisons are to the white dogs. The Karakachans and Kangals would go in closer proximity to sheep when threatened, and the researchers also observed that the Kangals and Karakachans barked less than the white dogs in response to the wolf decoy.

Young said her preliminary conclusion was that there was no statistical difference in sheep survival regardless of LGD used.

“They are all performing, they’re all protecting sheep, but doing it differently,” Young said. “Some bark more, some stay with the sheep more.” Further analysis of data gathered during the study might help to better define which traits are more dominant in which breeds, although these may be subtle differences.

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