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Mycobacterium bovis Survivability in Salt/Minerals Fed to Cattle PowerPoint PPT Presentation


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Mycobacterium bovis Survivability in Salt/Minerals Fed to Cattle. John B. Kaneene , DVM, MPH, PhD Joseph Hattey , MS Carol Bolin, DVM, PhD James Averill, DVM, PhD. Introduction.

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Mycobacterium bovis Survivability in Salt/Minerals Fed to Cattle

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Mycobacterium bovis survivability in salt minerals fed to cattle

Mycobacterium bovis

Survivability in Salt/Minerals

Fed to Cattle

John B. Kaneene, DVM, MPH, PhD

Joseph Hattey, MS

Carol Bolin, DVM, PhD

James Averill, DVM, PhD


Introduction

Introduction

  • The discovery of bovine tuberculosis (TB) in a wildlife reservoir(free-ranging white-tailed deer) in 1995, and subsequent discovery of TB-infected cattle herds in northeastern lower Michigan, have raised questions as to how the disease is being transmitted between deer and cattle.


Introduction cont

Introduction (cont.)

  • Research by Michigan State University, the USDA, and the Michigan Department of Agriculture (MDA) has implicated contaminated feedstuffs as possible vehicles for the transmission of Mycobacterium bovis, the causative agent of TB.


Introduction cont1

Introduction (cont.)

  • This research has been limited to plant-based feed materials (hay, carrots, grass, etc.), but has not been expanded to other possible substrates, such as salt/mineral blocks.


Introduction cont2

Introduction (cont.)

  • Salt blocks may pose a greater risk for disease infection in that they are not immediately consumed by a single animal at one time, but are used by several different animals, and can remain in place for weeks.


Introduction cont3

Introduction (cont.)

  • Whether or not salt is an inhospitable substrate for the survival of M. bovisis debatable.


Objective

Objective

To determine the survivability of M. bovis on salt and mineral blocks over time under normal weather conditions over a 12 month period


Experimental design

Experimental Design

Longitudinal Experimental Design


Collection of samples

Collection of Samples

Samples are taken from the top face of the salt block using sterilized scouring pads on a specified schedule.


Collection of samples cont

Collection of Samples (cont.)

Sample Collection Schedule

  • Within 1 hour after inoculation, and twice a day for the first week and once a day there after.

  • Three replicate pads were taken from each salt block at each sampling time.


Methods

Methods

Four Plain Salt and Four Mineral Blocks were used


Methods cont

Methods (cont.)

Pure cultures of M. bovis and M. fortuitum were applied to the surfaces and kept outdoors in BL-3 confinement cages for a year


Methods cont1

Methods (cont.)

Samples from the block surfaces were collected at specified intervals and tested for the presence of the organisms


1 percent of samples able to recover m bovis from salt blocks over time by season

Results

1. Percent of samples able to recover M. bovis from salt blocks over time, by season


2 percent of samples able to recover m bovis from salt blocks over time by sun shade

Results

2. Percent of samples able to recover M. bovis from salt blocks over time, by sun/shade


3 percent of samples able to recover m bovis from mineral blocks over time by season

Results

3. Percent of samples able to recover M. bovis from mineral blocks over time, by season


4 percent of samples able to recover m bovis from mineral blocks over time by sun shade

Results

4. Percent of samples able to recover M. bovis from mineral blocks over time, by sun/shade


5 percent of samples able to recover m fortuitum from salt blocks over time by season

Results

5. Percent of samples able to recover M. fortuitumfrom salt blocks over time, by season


6 percent of samples able to recover m fortuitum from salt blocks over time by sun shade

Results

6. Percent of samples able to recover M. fortuitumfrom salt blocks over time, by sun/shade


7 percent of samples able to recover m fortuitum from mineral blocks over time

Results

7. Percent of samples able to recover M. fortuitumfrom mineral blocks over time


8 percent of samples able to recover m fortuitum from mineral blocks over time by sun shade

Results

8. Percent of samples able to recover M. fortuitumfrom mineral blocks over time, by sun/shade


Conclusions

Conclusions

  • M. bovis can survive on shaded mineral blocks for over 3 days during the winter and still be viable.

  • The sunlight appears to shorten the viability of the M. bovisto 48 hrs on mineral blocks.

  • The salt blocks, both sun and shade, have a shorter survivability for the M. bovis than the mineral blocks.


Implications of the results of this study to bovine tb control strategies

Implications of the Results of This Study to Bovine TB Control Strategies

  • Demonstrates salt/mineral as potential source

  • Will be included as potential risk with infected herds

  • Use caution in how you administer salt/mineral during winter months


Acknowledgments

Acknowledgments

Michigan Department of Agriculture and Rural Development

Center for Comparative Epidemiology, Michigan State University


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