Type of Document Master's Thesis Author Masiello, Stephanie Noelle URN etd-03032010-104810 Title Implications of the ability of Enterococcus spp. to survive the ensiling process and bovine gastrointestinal tract on the risk of bovine mastitis Degree Master of Science Department Dairy Science Advisory Committee
Advisor Name Title Petersson-Wolfe, Christina S. Committee Chair Akers, Robert Michael Committee Member Elvinger, Francois C. Committee Member Mullarky, Isis K. Committee Member Sumner, Susan S. Committee Member Keywords
- bovine mastitis
- silage inoculant
- Enterococcus spp.
Date of Defense 2010-01-25 Availability unrestricted AbstractThree studies were conducted to assess if the ability of Enterococcus spp. surviving the ensiling process and bovine gastrointestinal tract could impact risk of bovine mastitis.
The first study determined ability of enterococci to survive 3 wk ensiling. Grass and corn crops were divided into 3 treatments: 2 commercial silage inoculants, 1 negative control. After wk 1, 2, and 3 of ensiling, dry matter and bacterial enumeration were performed. Addition of silage inoculant led to greater levels of enterococci in grass silage compared with negative control levels, but showed less difference in inoculated corn silage. The second study quantified enterococci shedding rates in lactating dairy cows. Using a 4 x 4 Latin Square design, lactating, ruminally fistulated Holsteins were inoculated with enterococcal isolates from silage inoculants, ensiled forages, or clinical mastitis cases. Over the 4-period study, each period consisted of rumen and fecal sampling (2 wk) followed by a wash period (10 d). There were no significant differences in rumen or fecal enterococci levels between the 4 treatments. Both rumen and fecal enterococci levels showed significant differences between baseline and treatment periods (period 3, 4). The third study analyzed similarity in enterococcal isolates of silage and bovine origin using pulsed-field gel electrophoresis patterns from SmaI restrictions. Dendogram analysis showed none of the isolates met or were greater than a 75% genetic similarity and produced a genetically diverse population. Results suggest Enterococcus spp. from silage inoculants are not likely to contribute to an increased risk of enterococcal bovine mastitis.
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