Animal & Avian Sciences Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2741
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Item Immune response after intramammary challenge with Streptococcus uberis mastitis for cows fed OmniGen-AF® during mid-lactation(2021) Fischer, Amanda; Kohn, Richard; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Mastitis is one of the costliest diseases in the dairy cattle industry. Environmental pathogens, such as Streptococcus uberis (Strep. uberis), are the most prevalent causes of mastitis infections, while contagious pathogen mastitis has declined in incidences due to improvement in management protocols. Antimicrobials and antibiotics are the primary therapies currently utilized in the dairy industry to treat mastitis. However, the concern for antibiotic overuse and potential bacterial resistance due to improper use of these therapies has steered research in exploration of alternatives to antibiotics or other strategies. One potential alternative is supplementation of an immunomodulatory feed additive to daily cattle total mixed rations (TMR). A current immunomodulator is OmniGen-AF ® (OMN) produced by Phibro Animal Health Corporation (Teaneck, NJ) and has been explored being fed to lactating dairy cattle by previous research groups. OmniGen- AF ® has been reported to improve initial innate immune response during infection. However, it is unknown how OMN influences the innate immune system in vivo to a S. uberis mastitis infection. The ability of OMN to modulate immune function during an environmental mastitis infection was tested compared to control groups. Cows fed OmniGen-AF® and challenged with Strep. uberis had numerically higher least squared mean Log somatic cell count compared to the control group that was not fed OMN and challenged with Strep. uberis. OMN fed cows displayed numerically higher average daily feed intake and fluid milk yield values compared to the control group. Further analysis of milk and blood samples using immunoassays to monitor the effects OMN has on cytokine and cortisol levels throughout mastitis infection is needed to determine innate immune response. In conclusion, OmniGen-AF® has the potential as an immunomodulator that improves innate immune system activity with continuous supplementation in the diet to prevention of dairy cattle environmental mastitis.Item In Vitro Study of an Orange Oil Derived Alternative to Antibiotics in the Treatment of Bovine Mastitis(2015) Federman, Cassandra Skye; Biswas, Debabrata; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bovine mastitis is a costly disease in the U.S. dairy industry. Its major causative agent Staphylococcus aureus is often unresponsive to antibiotic therapy. Our first study examined terpeneless, cold-pressed Valencia (CPV) orange oil as a possible alternative to antibiotic therapy in the treatment of S. aureus associated bovine mastitis. Orange oil showed significant inhibition of S. aureus growth and invasion of bovine epithelial mammary cells, but only modest reductions in pre-formed biofilms, which contribute to persistence of S. aureus infections. Our second study examined major components of terpeneless, CPV orange oil. Of four major compounds tested, only citral and linalool had significant inhibitory effects on S. aureus growth. In addition, they were capable of reducing pre-formed biofilms as well as association and invasion to bovine epithelial mammary cells. Part of this inhibition was due to downregulation of virulence and biofilm genes.