Identification of Mannheimia Haemolytica Shedding Dynamnics of Domestic Sheep under Range Conditions
Animal Diseases Research
2011 Annual Report
1a.Objectives (from AD-416)
Develop effective strategies for limiting or eliminating the shedding of respiratory pathogens from domestic sheep under range conditions. Data clearly shows that Mannheimia Haemolytica strain A2, found in domestic and bighorn sheep can lead to population limiting pneumonia is bighorn sheep and economic losses in domestic sheep. Working collaboratively with the University of Idaho and the United States Sheep Experiment station the pattern of respiratory pathogen shedding including M. haemolytica will be identified under different seasonal and management range conditions. Domestic sheep identified as “shedders” will be used to test methods such as completive inhibition to limit or eliminate pathogen shedding.
1b.Approach (from AD-416)
The conditions and level(s) of M. haemolytica shedding from domestic sheep is a critical issue for the development of policy concerning the grazing of domestic sheep under range condtions, especially where there is potential contact with bighorn sheep. Nasal swabs will be collected from 125 domestic sheep under three different seasonal and/or range conditions at the USSES. Such samples will be sent to the microbiological laboratory at Caine Center, the University of Idaho. Samples will be processed for the presence and level of M. haemolytica and Mycoplasma species. At the completion of sampling (three samplings per year for 3 years) “high” shedding and “low” shedding sheep will be identified and transported to ARS laboratory in Pullman, WA. These sheep will be treated with leukotoxin free Bibersteinia trehalosi which has been shown to inhibit M. haemolytica by contact dependent inhibition. Treated sheep will then be tested for their ability to shed M. haemolytica.
Samples were collected to examine and quantify bacterial flora in the nasal secretions of domestic sheep. Analysis was initiated on these data, which represent the first study to quantify a broad range of nasal secretion bacteria in domestic sheep under range conditions. In the next year, the analysis of these data will be completed and a manuscript submitted to report the results. Monitoring activities include email, teleconferences, providing technical advice to Cooperator laboratory personnel, and discussions during visits to ARS facilities by the Cooperator principal investigator.