Recipient Organization
IOWA STATE UNIVERSITY
S. AND 16TH ELWOOD
AMES,IA 50011
Performing Department
Veterinary Medicine
Non Technical Summary
Project Summary Johne's disease is widespread in dairy and beef cattle herds in the United States. An effective vaccine (Mycopar) approved by USDA and Iowa Department of Agriculture is available for vaccinating calves 1 to 35 days of age. Published information demonstrates that vaccination of calves with Mycopar markedly reduces or eliminates shedding of Map in feces and reduces up to 90% of cases of clinical Johne's disease A problem is that some producers and veterinarians are concerned with the large objectionable injection site responses that occur in a small percentage of the vaccinates; therefore, there is need to evaluate the use of a reduced dose of Mycopar. The use of a reduced dose of Mycopar minimizes the development of injection site responses. This is important to producers in the control of Johne's disease. Since Mycopar is effective in limiting the economic losses due to Johne's disease, there has been a marked increase (7 fold) in the use of Mycopar to vaccinate calves in the control of Johne's disease over a 10 year period (Figure). Source: Dr. R. Wheeler, Iowa Department of Agriculture. The hypothesis of this study is that shedding of Map and the development of clinical disease in cattle receiving a reduced dose of Mycopar will not be significantly different from the results obtained using a full dose of Mycopar. The efficacy of full dose and of reduced dose will be based on fecal shedding of Mycobacterium avium ss paratuberculosis (Map) in feces and the occurrence of clinical Johne's disease. Plans are to conduct investigations in 2010/2011 and in 2011/2012. The rationale being that the progression of disease varies for different animals and that animals shed Map intermittently. Data collected will be tabulated and included in preparation of a final report for ILHAC and for consideration for publication in a refereed journal pending completion of work outlined in this proposal.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
Objectives: 1. To obtain information on the shedding of Map in feces of cattle vaccinated with full dose of Mycopar vaccinated or with a reduced dose of Mycopar during a 6 month period from 9-1-11 to 3-1-12 2. To determine injection site swellings in cattle during the same time interval. 3. To determine the occurrence of clinical Johne's disease in cattle in each of the 3 groups 4. To obtain milk production records on each of the 3 groups.
Project Methods
Experimental Approach: The significance of the research outlined in this proposal is designed to obtain information on the efficacy of a reduced dose of Mycopar to eliminate shedding of Map in the feces of cows vaccinated as calves 1 to 35 days of age. Seven-hundred fifty cows had an incidence of Map-infection, and was estimated to be 10% or greater. In 2007/2008, calves were randomly assigned to treatment groups with approximately equal numbers of calves in each treatment group. Group I calves were inoculated subcutaneously in the brisket with a full dose of Mycopar. This is the dose routinely used and approved by the Iowa Department of Agriculture and the United States Department of Agriculture. Group II calves were inoculated with 1/2 dose of Mycopar at the same site. Group III calves were controls and were not injected. The injection site responses were observed during a 5-month period from 1-1-09 to 5-1-09. Cattle used in this investigation include calves vaccinated from 4-18-2007 to 3-05-2008. Under ideal conditions all animals would be vaccinated at a specific time interval; however, this is a field study and that was not possible. These cattle were a part of a previous study designed to determine if swellings induced by the use of Mycopar (heat-killed Mycobacterium paratuberculosis in oil) in calves 1 to 35 days of age could be minimized or eliminated by use of a reduced dose of Mycopar. Injection sites were observed over a 5 month period beginning on 1-1-09 to 5-1-09. Eighty-nine percent of the cattle had baseball size (2.5 inches in diameter) or smaller injection site responses when observed; the animals ranged in age from 14 to 22 months at the time of evaluation. Five percent of the injection site responses observed was classified as softball size. Eighteen of 286 (6%) cattle receiving full dose of Mycopar had injection site responses greater than softball size, whereas only 5 of 286 (1.7%) of the animals receiving the reduced dose had injection site responses greater that softball size. Therefore, a comparison of injection site responses revealed a 73% reduction in the number of responses greater than softball size in calves receiving a reduced dose of Mycopar as compared the number of responses observed in calves receiving full dose of Mycopar. In summary, the values of the injection site response is vaccine dose dependent . In the proposed work the Mycopar injection site will be observed during a 6-month period from 9-1-11 to 3-1-12. The producer will be requested to note any significant swellings observed at other time intervals and to notify the Veterinarian at the time of herd health examination. Also, fecal specimens will be collected during a 6-month period from 9-1-11 to 3-1-12 for the isolation of Mycobacterium avium ss paratuberculosis. Mycobactereologic examinations will be conducted on the fecal specimens and the results tabulated. Analysis of variance (ANOVA) will be used to compare the difference of the means of each of the vaccinated groups and control groups.