Implications of the ability of Enterococcus spp. to survive the ensiling process and bovine gastrointestinal tract on the risk of bovine mastitis

Three 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.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Dairy Science

Department dc:contributor.department

Dairy Science

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2010

Author dc:creator

• Masiello, Stephanie Noelle

Chair dc:contributor.committeechair

• Petersson-Wolfe, Christina S.

Committee members dc:contributor.committeemember

• Elvinger, Francois C.
• Sumner, Susan S.
• Akers, Robert Michael
• Mullarky, Isis K.

• bovine mastitis
• shedding
• silage inoculant
• Enterococcus spp.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-03032010-104810

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/31403